Abstract: The prokaryotic community of a groundwater aquifer exposed to high concentrations of tetrachloromethane (CCl4) for more than three decades was followed by terminal restriction fragment length polymorphism (T-RFLP) during pump-and-treat remediation at the contamination source. Bacterial enrichments and isolates were obtained under selective anoxic conditions, and degraded 10 mg·L−1 CCl4, with less than 10% transient formation of chloroform. Dichloromethane and chloromethane were not detected. Several tetrachloromethane-degrading strains were isolated from these enrichments, including bacteria from the Klebsiella and Clostridium genera closely related to previously described CCl4 degrading bacteria, and strain TM1, assigned to the genus Pelosinus, for which this property was not yet described. Pelosinus sp. TM1, an oxygen-tolerant, Gram-positive bacterium with strictly anaerobic metabolism, excreted a thermostable metabolite into the culture medium that allowed extracellular CCl4 transformation. As estimated by T-RFLP, phylotypes of CCl4-degrading enrichment cultures represented less than 7%, and archaeal and Pelosinus strains less than 0.5% of the total prokaryotic groundwater community. Because of its hazardous effects on human health [4 is regulated under the Montreal Protocol since 1987. Nevertheless, worldwide CCl4 emissions remain high  [4-degrading enrichment cultures obtained from samples taken at the contamination source. This led to the isolation of the novel CCl4-degrading bacterial strain Pelosinus sp. TM1.The purpose of this study was to investigate the CClUnless otherwise stated, all chemicals and reagents were of analytical grade and obtained from Sigma-Aldrich Co.  or Thermo Fisher Scientific .4-polluted site was collected in October 2007 (T1), April 2008 (T2) and December 2008 (T3), i.e., 14, 20 and 28 months after the start of “pump-and-treat”. Sampling was performed at the location of the initial spill by diverting 100 (T1 and T2) or 1000 (T3) liters of pumped groundwater before physico-chemical remediation. pH and redox potentials were measured using a pH 330i pH-meter  equipped with a SenTix Mic or a SenTix ORP electrode for pH or Eh determination, respectively. Mineral composition was determined by groundwater analyses carried out by the Centre d’Analyses et de Recherches in Strasbourg. Samples were concentrated by tangential filtration using a Prep/Scale TFF cartridge with a molecular weight cut-off of 30 kDa , or with a Sartocon slice ultrafiltration set equipped with 5 polyethersulfone membranes of 0.1 m2 . Sample volumes were further reduced from 300–400 mL to 10–20 mL by Centricon Plus-70 centrifugal filter devices , or by centrifugation at 10,000 g for 30 min in an Optima L90K ultracentrifuge equipped with a fixed angle 45Ti rotor . Cell densities were estimated using a DM 4000B epifluorescence microscope  and fluorescent (SYBR Green I) intracellular DNA staining as described [Groundwater from the studied CClescribed .Methanosarcina barkeri medium n°120a from the German culture collection DSMZ. C medium contains 10 g yeast extract and 0.5 g tryptone per L and was prepared as described [Pseudomonas stutzeri KC [Methanosarcina barkeri DSM 1538 [4. Simulated groundwater medium (SGW), modified from [2SiO3·5H2O, 0.16 g Na2CO3, 0.006 g Na2SO4, 0.02 g KOH, 0.15 g MgSO4·7H2O, 0.0125 g Ca(NO3)2·4H2O, 1.6 g Na2HPO4, 0.8 g KH2PO4 and 1 mL of trace elements solution. pH was adjusted to 7.5–7.8 with 10 M NaOH prior to autoclaving at 121 °C for 10 min. Individual salt solutions and trace elements were added separately as sterile 100× concentrated stock solutions after autoclaving. When used as solid medium, 15 g·L−1 bacteriological agar  was added. After sterilization, medium for anoxic growth was transferred into 500 mL glass infusion bottles  sealed with Teflon-coated rubber stoppers , then flushed under a continuous flow of nitrogen  for 1 h. After transfer to an anoxic glovebox , media were reduced by addition of 0.3 g·L−1 Na2S·9H2O and 0.3 g·L−1l-cysteine·HCl. The redox indicator resazurin  was added to liquid media at a final concentration of 1 μM.Three culture media with different carbon and energy sources and electron acceptors were used. MBM medium (containing (per L) 2 g yeast extract, 2 g casitone and 10 mL methanol) corresponds to escribed . Pseudomtzeri KC  and MethDSM 1538  were useied from  to reduc4 concentrations , carbon sources , and electron acceptors  were tested (2-depleted medium. Carbon and energy sources and electron acceptors were added as 100× concentrated sterile stock solutions in water as summarized in 4 solutions (800 mg·L−1) were prepared using ultrapure CCl4  and added last to culture media. Inoculation of enrichment cultures was done with 100 μL aliquots of concentrated groundwater samples from campaigns T1 and T2, representing between 0.5 and 1.0 L of the initial groundwater samples. Growth was measured at 600 nm directly in Hungate culture tubes with a Libra S6 spectrophotometer equipped with a 16 mm culture tube adapter . Enrichment cultures for selected samples were obtained under the same conditions by successive reinoculation with 100 μL of stationary phase cultures (OD 0.2–1.0).Liquid enrichment cultures (5 mL) were carried out at 25 °C in 17 mL Hungate tubes sealed with Viton rubber stoppers  in MBM, C and SGW media. Several CCle tested . Oxic in4 was quantified using a CP 3800 gas chromatograph connected to a flame ionization detector . Headspace aliquots (500 μL) were collected from sealed Hungate culture tubes with a gastight 1750 syringe  and injected onto the GC column . Separation of volatile compounds was achieved by isothermal elution at 30 °C for 1 min, followed by a linear temperature gradient (20 °C min−1) up to 220 °C. Injector and detector were maintained at 220 °C (splitless mode) and 300 °C, respectively, with nitrogen (N2) as the make-up gas (Linde Gas). Peak areas were analyzed with Galaxie Workstation software (Varian) and expressed as percentage of CCl4 compared to an abiotic reference tube prepared under the same conditions.CCl4 degradation rates in growing cultures of dechlorinating enrichments and of strain TM1 were calculated by determining the amount of CCl4 degraded per day and per mg of total cellular protein upon culturing under the respective conditions described in 4 degradation and chloride production were determined in cell suspensions of strain TM1 grown in SGW medium. Cell cultures (50 mL OD600 0.15–0.20) were centrifuged at 10,000 g for 15 min, resuspended  in 5 mL 10× diluted SGW medium in 30 mL sealed anoxic flasks under a nitrogen atmosphere, and exposed to 65 μM (10 mg·L−1) CCl4 at 25 °C. Headspace samples were taken for GC measurements as described above, and 550 μL aliquots of the cell suspension were removed for determination of protein content and chloride concentration. Briefly, aliquots were spun down and an appropriate dilution of the supernatant analyzed by ion chromatography on an AS18-AG18 column  eluted with 34 mM NaOH at 1 mL per minute. Protein measurements were performed on cell pellets resuspended in 0.1 M NaOH, lysed at 95 °C for 10 min and centrifuged at 12,000 rpm for 5 min. Aliquots of the resulting solutions were analyzed with the bicinchoninic acid kit (Sigma) following the manufacturer’s protocol, using bovine serum albumin (BSA) as a standard. For analysis of CCl4 degradation in spent medium, culture supernatants were separated from cells of a 500 mL culture grown in SGW medium by centrifugation for 15 min at 7650 g in a Sorvall Evolution RC centrifuge equipped with a SS-34 rotor (Thermo Fisher Scientific). Supernatants were filter-sterilized using 0.22 μm cellulose acetate syringe filters . Corresponding cell pellets were washed and resuspended in an equivalent volume of 50 mM phosphate buffer, pH 7.5. Heat treatment was performed by autoclaving , and oxygen-exposed samples were obtained by contact with air for 90 min under sterile conditions. Part of the oxygen-exposed supernatant fraction was cysteine/Na2S-treated by addition of 0.3 g·L−1 Na2S·9H2O and 0.3 g·L−1l-cysteine·HCl. Degradation rates in supernatants were expressed as μg CCl4 day−1 per mL of bacterial culture, normalized for a culture at OD600 = 1.0.Specific CCl−1, phenol 50 g·L−1, ethanol 100 mL·L−1) was used for staining instead of 1% aqueous safranin.Substrate utilization profiling of strain TM1 was performed under anaerobic conditions with an AN MicroPlate  according to the manufacturer’s recommendations, except that incubation was set to 25 °C for 72 h in an anoxic glove box. Staining of spores was carried out as described , except 7 to 109 cells trapped in agarose plugs [8 cells suspended in 40 μL sterile ultrapure water or NaOH 0.05 M, and heated at 95 °C for 10 min. The resulting solution was cooled on ice for 5 min, diluted (1/15) in sterile ultrapure water and used as template for PCR amplification.Total DNA from environmental samples or enrichment cultures was purified and isolated from 10se plugs . DNA conAluI and HhaI, RDP release 10 update 27 , and 10 mismatches allowed within 15 bases from 5′ end of primers. Data obtained with different fluorochromes for internal marker and sample fragments permitted determination of the total number of T-RFs and their relative proportion. The peak integration threshold was set to 500 ppm of the total integrated fluorescence. Bacterial diversity was evaluated using the Shannon diversity index (H′) [ip is the relative area of T-RFLP peak i and S is the total number of integrated peaks (richness) in the sample. The distribution of T-RFLP peak areas was also evaluated using a measure of evenness (E):PCR reaction mixtures, cycles and primers for bacterial T-RFLP were previously described . PrimersE = 1.0 would describe a sample with equal frequencies of all peaks in its T-RFLP profile.The maximum value −1, for separation of 16S rRNA gene fragments.D-HPLC was performed as described , using aGroundwater samples were fixed with 2% formaldehyde solution for 2 h. After washing with phosphate buffer saline solution (PBS), samples were stored in a 1:1 PBS/ethanol solution at −20 °C until used. For hybridization, 20 μL were filtered through 0.22 μm polycarbonate filters . Archaea were detected with the specific Cy3 monolabeled “S-D-Arch-0915-a-A-20” probe . After sAluI or HhaI restriction profile polymorphism of PCR amplicons obtained from cloned fragments with T3 and T7 universal primers, and visualized on NuSieve 3:1 Agarose gels . Sequences of PCR products, purified with ExoSAP-IT  following the manufacturer’s protocol, were obtained with primers 27f, 534r or rd1 on an ABI Prism 3130 XL sequencer . Similarity searches of the 16S rRNA gene sequences were performed using Blast and the Ribosomal Database Project [PCR reactions from enrichment cultures were performed with primers 27f and rd1 (5′-AAGCTTAAGGAGGTGATCCAG-3′), adapted from . Zero Bl Project .The 16S ribosomal RNA gene sequences obtained for selected bacterial strains enriched from the studied site were submitted to the EMBL database under accession numbers FN689722 to FN689728 and KP219716.4-degraders among the prokaryotic community of concentrated groundwater samples, enrichment cultures under 33 different selective conditions were set up for each of the collected samples in campaigns T1 and T2 , degradation of CCl4 was complete between six and 11 days after inoculation. Sustained CCl4 degradation in successive cultures was assessed by inoculating aliquots of stationary phase CCl4-degrading enrichments into fresh medium. Two types of degradation curves were observed after successive transfers  different fingerprints for each enrichment with exclusively bacterial content (no Archaea); (ii) shifts in community structure after successive transfers; and (iii) predominant phylotypes identified by database comparisons , a dissimilatory iron-reducing bacterium (DIRB) capable of CCl4 degradation under anoxic conditions in presence of ferric oxides and humic substances [Peptostreptococcaceae  as the potential electron donor, 10 times diluted yeast extract compared to C medium, and nitrate (10 mM) as nitrogen source). CCl4 degrading ability of strain TM1 was further assessed by estimating the amounts of chloride production from CCl4 degradation in cell suspensions of cultures grown in SGW medium with 10 mM pyruvate. Rates of CCl4 removal (0.8 nmol ± 0.2 CCl4 h−1 mg−1) and chloride production (2.8 nmol ± 0.4 Cl− h−1 mg−1) were compatible with a stoichiometry of four chloride ions produced per CCl4 consumed  and was at least in part responsible for CCl4 degradation.Living cells of e strain . The abiPelosinus sp. TM1 is the first isolate of the genus shown to be capable of dehalogenation. Nevertheless, P. fermentans R7 was shown to provide an essential corrinoid cofactor for Dehalococcoides reductive dehalogenases in a trichloroethene-dechlorinating syntrophic consortium [Pelosinus were isolated from sites contaminated with halogenated compounds including chlorinated alkanes [Pelosinus sp. TM1 afforded stable and complete dehalogenation of CCl4  [To our knowledge, nsortium , and sev alkanes ,38,39,40 of CCl4 , at ratectively) ,42.4-degrading microbial process in which CCl4 is used as a carbon or energy source for growth has not been identified [Pelosinus sp. TM1 also involves a co-metabolic process. In terms of carbon, the quantities and rate of degraded CCl4 under the tested conditions will at most only make a minor contribution to the biomass produced . In terms of energy, and although growth-promoting metabolism of CCl4 may be thermodynamically favorable [4 is used by Pelosinus sp. TM1 as an electron acceptor in energy-generating metabolism for growth. First, comparing the molar ratio of electron donor pyruvate (10 mM) to the amounts of CCl4 added to cultures in SGW medium (65 μM), CCl4 would have been growth limiting when used as an electron acceptor. Second, considerable amounts (>60%) of the initial CCl4 remained once Pelosinus sp. TM1 reached stationary phase under the chosen culture conditions. Finally, CCl4 degradation also occurred in spent medium, where it resisted heat treatment  (PDTC) which, when complexed to Cu(II), mediates extracellular dechlorination of CCl4 [12 and related corrinoid cofactors, which are produced and released to the extracellular compartment by a variety of microorganisms, also catalyze degradation of CCl4 [Pelosinus sp. TM1 mediating CCl4 degradation might indeed be related to corrinoid analogues, and such cofactors were shown to be produced by Pelosinus strains [A CClentified ,41,42. Savorable , the obtreatment , furtherW medium 5 μM, CCl of CCl4 . In addi of CCl4 ,34,43,44 strains , but fur4 for decades and enrichment and isolation of CCl4-degrading bacteria in the presence of CCl4 showed that only a minor fraction of the bacteria from this environment were capable of CCl4 degradation in the laboratory. Among those, strains from genera Klebsiella and Clostridium had already been associated previously with CCl4 degradation. In contrast, Pelosinus sp. TM1 isolated here is the first representative of the Pelosinus genus shown to sustain CCl4 degradation.Diversity analysis of the prokaryotic community of an aquifer contaminated by CCl


NK/T cell lymphoma. Treatment is with induction using a regimen utilized for leukemia. Allogeneic hematopoietic stem cell transplantation is recommended for those who achieve remission following induction.Blastic plasmacytoid dendritic cell neoplasm is an aggressive neoplasm with a median survival of only a few months despite treatment. An exhaustive immunohistochemical workup is required to differentiate it from myeloid sarcoma and extranodal  Peripheral blood  intravenously (IV) on days 1, 8, 15, and 22, cytarabine 3 g/m2 IV over 3 h bid for four doses on days 1 and 2, methotrexate 1 g/m2 continuous IV infusion (CIV) over 36 h on day 15, leucovorin 30 mg PO or IV starting 42 h after starting methotrexate every 6 h for six doses, L‐Asparaginase 10,000 units/m2/dose IV on days 3, 4, 16, and 17. Phase 2 with Dexamethasone 40 mg/day PO on days 1–4, 9 to 12, ifosfamide 500 mg/m2/day IV on days 1–4, vincristine 0.4 mg/m2 (max 2 mg) CIV on days 1–4, adriamycin 12 mg/m2 CIV on days 1–4, intrathecal therapy with methotrexate 12 mg on day 1 or 2, cytosine arabinoside 30 mg on day 1 or 2 and hydrocortisone 15 mg on day 1 or 2. He subsequently developed neutropenia and sepsis which progressed to septic shock, and he unfortunately expired. BPDCN is an aggressive hematological malignancy derived from the precursors of plasmacytoid dendritic cells. CD4, CD56, and CD123 expression are characteristic of BPDCN A 57‐year‐old male presented to the emergency department (ED) with generalized weakness and severe fatigue. He also experienced constitutional symptoms such as subjective fever, chills, night sweats, diffuse joint pain, and generalized body aches, and was recently treated with amoxicillin at an urgent care clinic for new‐onset dental pain. He completed the course of antibiotics, but his symptoms worsened before he decided to visit the ED. At the time of presentation, he also reported experiencing intermittent “red blotchy” spots on his skin which resolved on their own. Initial vital signs were within normal limits. Physical exam was unremarkable. Labs were remarkable for pancytopenia with neutropenia (white blood cells (WBC) 1.3 × 10ood Figs  smear shood Figs , HLA‐DR,None declared.MPR: wrote the case description. PB, SKK and SK: contributed to the description on AITL and the key clinical message. EBM: provided the description of the pathology images.


Polyfluoranthene, synthesized by an interfacial cationic oxidative polymerization of fluoranthene, emits visible fluorescence that shows highly selective sensitivity to Fe3+. n-hexane and nitromethane containing fluoranthene and FeCl3, respectively. A full characterization of the molecular structure signifies that the PFAs have a degree of polymerization from 22–50 depending on the polymerization conditions. A polymerization mechanism at the interface of the hexane/nitromethane biphasic system is proposed. The conductivity of the PFA is tunable from 6.4 × 10–6 to 0.074 S cm–1 by doping with HCl or iodine. The conductivity can be significantly enhanced to 150 S cm–1 by heat treatment at 1100 °C in argon. A PFA-based chemosensor shows a highly selective sensitivity for Fe3+ detection which is unaffected by other common metal ions. The detection of Fe3+ likely involves the synergistic effect of well-distributed π-conjugated electrons throughout the PFA helical chains that function as both the fluorophore and the receptor units.A novel polyfluoranthene (PFA) exhibiting strong visual fluorescence emission, a highly amplified quenching effect, and widely controllable electrical conductivity is synthesized by the direct cationic oxidative polymerization of fluoranthene in a dynamic interface between  Fluoranthene (FA) possesses unique properties6 such as stronger fluorescence emission, longer fluorescence lifetime and higher fluorescence quantum yield than theoretically expected values, and has therefore found application as a dopant of molecular crystals for laser spectroscopy. It is believed that polyfluoranthene (PFA), with greater delocalized π-conjugation and higher molecular weight, could exhibit even better electronic and optoelectronic properties, higher carbon yield, and much lower toxicity than FA and even oligofluoranthene (OFA) consisting of 5 FA units.12 Moreover, since PFA contains repeat units of three hexa-carbocyclic rings and one penta-carbocyclic structure resulting in some gaps in its molecular chains, this could possibly make the polymer soluble or fusible. In fact, FA-based polymers have shown unique performance including low band gaps with novel electronic, optical, and photovoltaic properties due to their ladder topologies and highly delocalized π-conjugation.13 Up to the present, however, the synthesis, structure and properties of PFA have been little studied because FA has so high an oxidation potential that it could not be simply oxidized under common oxidizing conditions. Polymers comprising repeating units based on FA and its derivatives have been synthesized by Suzuki coupling reactions from 7,10-bis-(4-bromo-phenyl)-8,9-diphenyl-fluoranthene or 7,10-bis-(4-bromo-phenyl)-8,9-bis-(4-octyl-phenyl)-fluoranthene.14 However, the synthetic methodology applied to the derivatives and polymers of FA is rather sophisticated and costly. Electropolymerization has been successfully used to prepare PFA, but the resulting PFA films are structurally non-uniform and brittle, exhibiting low electrical conductivity,15 and poor solubility, thus preventing their processing and wider application. Additionally, the electrosynthesized PFA films have low thermal decomposition temperatures and char yields which are much lower than theoretically estimated values.16 In particular, the electropolymerization may also impede mass production since the synthetic productivity of PFA completely depends on the surface area of the noble metal electrode used.Conjugated aromatic polymers emit strong fluorescence that can be sensitively quenched by a specific substance.3NO2) containing both FA and FeCl3 produces OFA with the ability to emit long-wavelength fluorescence at long excitation wavelengths along with high sensitivity to Fe3+ and picric acid. However, the drawbacks include relatively low synthetic yield, modest electrical conductivity, low thermal stability, and some toxicity.12 Here we demonstrate a novel method to efficiently synthesize PFA by an interfacial chemical oxidative polymerization of FA at a dynamic interface between n-hexane (C6H14) and CH3NO2 containing FA and FeCl3, respectively.17 The inspiration to directly synthesize PFA from FA originates from the specially π-conjugated system of FA. The synthesis, structure, properties, and functionalities of PFA were carefully explored and optimized by regulating synthetic parameters including the reaction medium, the method of mixing FA and FeCl3, the C6H12/CH3NO2 and FeCl3/FA ratios, polymerization temperature and time. Not only were the PFAs thoroughly characterized by using 13 modern investigative techniques, but the mechanism of the chemical oxidative polymerization of FA is also elucidated. A high-performance Fe3+ chemosensor possessing high selectivity, a wide linear range, and a superior detection limit for Fe3+ is demonstrated.In a previous study we reported that the homogeneous chemical oxidative polymerization of FA in nitromethane  was dissolved in 10 mL CH3NO2 in another 250 mL conical flask. After the oxidant solution was filtered to remove impurities, the monomer solution at 70 °C was added drop-wise into the purified oxidant solution at 70 °C within 15 min. The reactant solution was continually stirred magnetically at 70 °C for 18 h. During the polymerization, the formation of a bilayer reaction was observed, and the PFA particles formed changed their color from brownish red to dark blue and then to black. The PFA particles were collected from the polymerization medium and further purified with ethanol, 1.0 M HCl, 1.0 M NaOH, and DI water by centrifugation in order to respectively remove residual FA monomer, residual Fe3+, residual HCl, and residual NaOH until the upper liquid in the centrifuge tube was colorless. No Fe3+ residue in the PFA was confirmed by dropping aqueous K4Fe(CN)6 into the upper liquid, since no Prussian blue was observed. Finally, a fine dark PFA powder was obtained after drying in air at 50 °C for 48 h, giving an apparent polymerization yield of 93.9%. The nominal polymerization of FA is illustrated in In a typical synthesis of PFA, FA  was ultrasonically dissolved in 15 mL 2 vapor doping and carbonization have been used in attempts to enhance the conductivity of PFA particles, where the pristine PFA powder was previously heated at 80 °C for 48 h to remove in situ doped HCl. (1) For HCl doping, a 2 g L–1 dispersion of PFA in 4.0 M HCl was ultrasonically stirred for 24 h. HCl redoped PFA powder was obtained after filtration and drying at 40 °C for 48 h. (2) Following an early I2 doping technique, PFA powder and I2 particles were placed in a closed vessel but did not touch each other, and then were heated at a constant temperature of 80 °C under atmospheric pressure for 48 h. Note that the PFA powder became much darker or even black after I2 doping, but the PFA powder remained almost unchanged in a gray color before and after HCl doping. (3) The pristine PFA powder obtained under the optimal conditions was carbonized at a temperature up to 1100 °C by heating at a rate of 3–20 °C min–1 under nitrogen or argon atmosphere for ca. 1 h, and then cooled down to room temperature at 3 °C min–1. A black char was obtained with a char yield of 52–60 wt%.Three techniques including HCl doping, I2SO4 were obtained on a Perkin-Elmer Instruments Lambda 35 UV-vis spectrophotometer at a scanning rate of 400 nm min–1. ATR-FT-IR spectra were obtained with a Nicolet Magna-IRTM 550. Raman spectra of the solid powder of the PFA and the PFA-based char were achieved by British Renishaw inVia Raman Microscope (Bert) with a 785 nm red laser pumped by solid state diode. Elemental analysis was conducted using an Elementar Vario EL analyzer by Stephen Boyer at London Metropolitan University, UK. NMR spectra were obtained on Bruker spectrometers of AV700 for 1D 1H-NMR at 700 MHz, DQX400 for 2D 1H–1H COSY NMR at 400 MHz and AVC500 for 13C-NMR and 1H–13C HSQC at 500 MHz in DMSO-d6 at the University of Oxford, UK. The MALDI-TOF MS of the PFAs in THF with sinapinic acid as the matrix was recorded on a mass spectrometer by MALDI micro MX™ MICROMASS MS Technologies, Waters. Wide-angle X-ray diffraction patterns were scanned on a Philips X'pert Pro powder diffractometer using copper-monochromatized CuKα radiation (λ = 0.154178 nm). Fluorescence spectra were performed at the CNSI Advanced Light Microscopy/Spectroscopy Shared Facility at UCLA, USA. The quenching experiments of the fluorescence emission of 3 mL optimal PFA solution at 10 mg PFA/1 mL DMSO were carried out by adding 0.2 mL metal-ion aqueous solution. The melting point of FA and PFAs was determined using hot-stage optical microscopy. Simultaneous thermogravimetry and differential thermal analysis measurements were performed at a heating rate of 20 °C min–1 in nitrogen in a temperature up to 1000 °C and sample mass of 25 mg by using a NETZSCH STA 449C Jupiter thermogravimetric apparatus. The bulk electrical conductivity of an approximately 0.5 mm thick pressed disk of the PFA particles with an effective area of 0.785 cm2 was measured by a two-probe method.UV-vis spectra of the PFA in NMP or 98% H2H5OH, CH3COOH, propylene carbonate, n-C6H14, CH3CN, CHCl3, CH3NO2, and an immiscible biphase of CH3NO2/C6H14 were examined as the medium for the chemical oxidative polymerization of FA. No dark polymer precipitates appear if C2H5OH, CH3COOH, propylene carbonate, or C6H14 are used as a single polymerization medium. A brown PFA precipitate was obtained in CH3CN or CHCl3, but 3NO2 shows a weak double peak at 500 and 534 nm that was not observed in the FA monomer. It appears that none of these seven solvents provide a suitable reaction medium for the synthesis of PFA with a satisfactorily large π-conjugated structure. Fortunately, the polymerization of FA in an immiscible biphasic solvent comprising CH3NO2/C6H14 can afford a black PFA that exhibits a much stronger double peak in exactly the same wavelength range from 500 and 534 nm, i.e., this PFA product has a much larger π-conjugation length and/or higher molecular weight, significantly higher synthetic yield, considerably higher melting temperature, enhanced char yield at 1000 °C, and much higher conductivity than the OFA synthesized in CH3NO2 only,12 as summarized in 3 in C6H14 and CH3NO2; (2) the moderate solubility of FA monomer in CH3NO2; and (3) the slight solubility of FeCl3 in C6H14, a slow but persistent interfacial polymerization between C6H14 and CH3NO2 is likely responsible for the formation of PFA with a large π-conjugation length. Conversely, the chain termination of FA polymerization with FeCl3 in a single solvent such as CH3NO2, CH3CN or CHCl3 may occur too early to form high molecular weight PFA. This is because early precipitation of growing macromolecular chains resulting from much lower solubility of PFA in the three single solvents will cause chain termination that can be avoided in CH3NO2/C6H14 as a result of better solubilization of FA and its active oligomers or intermediates. The novelty of the present study is that a new FA polymer having a new macromolecular structure and much higher performance has been achieved by a high-yield polymerization at the interface between CH3NO2 and C6H14 in an immiscible biphasic system. As a result, CH3NO2/C6H14 is considered as an ideal polymerization medium for the following investigation.Seven typical organic solvents including C3NO2 and C6H14 containing FeCl3 and FA, respectively, where a big difference of density exists (CH3NO2 (1.127 g mL–1) and C6H14 (0.659 g mL–1)). Three contact modes between monomer and oxidant were used in this study, including drop-wise addition of FA solution into FeCl3 solution, drop-wise addition of FeCl3 into FA, and direct mixing. In this study, all UV-vis spectra were normalized based on the strongest absorption of π-conjugated fused aromatic rings at 260–290 nm (band I), which was used as an internal standard in order to quantitatively analyze and compare the large π-conjugated structures of various PFAs. It is known that conjugated polymers possess more and longer π-conjugated structures if their UV-vis spectra exhibit stronger absorptions at longer wavelengths.19 In this way, the conjugation degree of PFA chains could be semi-quantitatively evaluated by the intensity ratio of the strongest band at 499–660 nm to band I at 287–310 nm.The contact between monomer and oxidant during polymerization is one of the most critical parameters for the PFA synthesis. The polymerization of FA was conducted at a dynamic interface between CH3 solutions significantly influences the polymerization of FA at a fixed reaction condition of C6H14/CH3NO2 volume ratio of 3/2 and FeCl3/FA molar ratio of 5 at 50 °C for 24 h. The drop-wise addition of FeCl3 solution into FA solution can produce PFA with the longest band III at a wavelength of 537 nm, and thus the longest π-conjugation, but the lowest polymerization yield of 60.5%, the smallest π-conjugation degree of 0.083, and the lightest yellow colored powder. In contrast, the drop-wise addition of FA solution into FeCl3 solution can achieve an optimal PFA demonstrating the highest polymerization yield of 72.4%, the darkest brown color, and the largest π-conjugation degree of 0.352 (3 is the best way of mixing the two reactants. Based on the densities of FeCl3 (2.898 g cm–3) and FA (1.252 g cm–3), it is obvious that the FeCl3/CH3NO2 solution is over twice as dense as the FA/C6H14 solution. When the addition of the dense FeCl3/CH3NO2 solution into the lighter FA/C6H14 solution was made, the redox polymerization between FeCl3 and FA did not satisfactorily progress because most oxidant rapidly sank to the bottom of the reaction vessel. In other words, the contact area between oxidant and monomer was insufficient to effectively produce PFA with a large degree of conjugation. Rapid direct mixing in one portion may cause dramatic polymerization in a short period of time, leading to insufficient conversion of FA and subsequently incomplete chain propagation. Fortunately, with the drop-wise addition of the lighter FA/C6H14 solution into the denser FeCl3/CH3NO2 solution, the suspended FA/C6H14 solution on the top of the oxidant solution not only creates enough space for interfacial controlled polymerization, but also provides adequate time for polymer chain propagation, ultimately resulting in the formation of PFA with a large π-conjugated structure. Therefore, the drop-wise addition of the light FA solution into the denser FeCl3 solution is an optimal feed method and therefore used for the following study.It can be seen from of 0.352 , regardl6H12/CH3NO2 volume ratios at a fixed total volume of 25 mL are shown in 6H14 fraction in the biphase media. The highest yield up to 88%, the strongest band III, and the highest degree of π-conjugation are simultaneously achieved for the PFA synthesized at a C6H14/CH3NO2 volume ratio of 3/2. The PFA obtained is also the darkest black. Clearly, the optimal C6H14/CH3NO2 volume ratio is 3/2 for the synthesis of PFA having the best comprehensive performance. Perhaps, too little C6H14 leads to a fast FA transfer into the CH3NO2 phase, thereby weakening the probability of interfacial polymerization, while too little CH3NO2 does not produce adequate interfacial area to effectively initiate polymerization. As a result, the C6H14/CH3NO2 volume ratio of 3/2 was selected as an optimal biphasic volume ratio for the following study.The UV-vis absorption spectra of PFA obtained by four C3/FA molar ratio of 5 for 24 h, the yield monotonically increases and reaches the highest value of 88% at 80 °C since high temperature can effectively activate the H-elimination reactivity on FA molecules and thereby result in efficient oxidative polymerization of FA. On the other hand, the contact area at the biphasic interface of C6H14/CH3NO2 could increase due to faster diffusion and more dramatic thermal motion of the reactants at higher temperature, thus enhancing the interaction of oxidants with monomers. This increase in the yield is opposite to significantly exothermic polymerizations of diaminonaphthalene,20 and diaminoanthraquinone,21 but matches the chemical oxidative polymerization of benzene,22 pyrene,23 and thiophene17 because they have similar dehydrogenation activity. However, the PFA in both solvents presents its maximum degree of π-conjugation at 70 °C, indicating that 70 °C is the best temperature to obtain PFA with the longest π-conjugated chains. Further elevation of the temperature is counter productive because a very high temperature accelerates polymerization, but also deteriorates the regularity of the PFA chain structure. Another reason is that the interface may be destroyed at too high a temperature because of the low boiling point of C6H14, although the reaction system was refluxed during the polymerization. Overall, 70 °C is the most suitable temperature for the synthesis of highly π-conjugated PFA, as discussed below.The effect of polymerization temperature on the synthetic yield and conjugation degree of the PFA is demonstrated in 3/FA molar ratio of 5 at 50 °C. With increasing polymerization time from 2 to 24 h, the polymerization yield and conjugation degree both rise steadily at first and subsequently decrease slightly. The maximum yield and degree of π-conjugation appear at a polymerization time of 18 h. A similar relationship between the time and polymerization yield is also found in the chemical oxidative polymerization of aniline.24 Generally, most chemical oxidative polymerizations have three typical reaction stages. In this case, first, FA monomers are quickly oxidized or initiated by FeCl3 and immediately converted into cationic radicals. Second, a strong interaction between the cationic radicals and monomers of FA lead to chain propagation, resulting in the formation of intermediate active PFA with high molecular weight. Third, the interaction between the intermediate active PFAs and/or FA monomers terminates the polymerization during the final stage of the polymerization. It is likely that increased polymerization time to 18 h is beneficial to chain propagation, but too long a polymerization time would cause an over oxidation of the PFA and thereby impair the yield and π-conjugation degree to some extent.3 oxidant/FA monomer ratio on the synthetic yield and π-conjugation degree is summarized in 3/FA molar ratio is increased from 3 to 9, demonstrating a maximum value at the FeCl3/FA molar ratio of 7. Note that the color of PFA powder gradually changed from light green (FA monomer) to brownish red, brown, dark black, and black after oxidation by the FeCl3/FA molar ratios of 3, 5, 7, and 9, respectively  in NMP, and the darkest black as can be seen in The influence of FeClectively . That is1H–1H COSY, 2D 1H–13C HSQC, 13C NMR, 1H NMR, GPC, and MALDI-MS techniques. 25 but no absorption bands at wavelengths longer than 400 nm. Although the PFA displays slightly different bands between 200 and 400 nm, it also demonstrates three new bands between 400 and 900 nm. These additional bands at longer wavelengths can be assigned to the large π-conjugated structure of PFA chains. Notably, the UV-vis spectra of PFA are quite different in each solvent, in which the bands between 400 and 900 nm are weaker and appear at longer wavelength in H2SO4 than in NMP. This suggests that the PFA exhibits significantly different chain conformations and doping levels. The weakest band at 800 nm in H2SO4 may be related to the extension of the large π-conjugated electrons along the macromolecular chains. It is surprising to discover that the PFA synthesized in this study has much stronger UV-vis bands than electropolymerized PFA,9 indicating that the PFA obtained by chemical oxidative polymerization of FA is a longer π-conjugated polymer with much higher molecular weight.The molecular structure of the synthesized PFA was systematically characterized by a combination of UV-vis, IR, Raman, elemental analysis, 2D 3/FA ratios in the biphase system are presented in –1 due to C PBM data was replaced with SVG by xgml2pxml:<glyph-data id="z.dbd" format="PBM" resolution="300" x-size="34" y-size="34" xml:space="preserve"> 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000	</glyph-data><svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="16.000000pt" height="16.000000pt" viewBox="0 0 16.000000 16.000000" preserveAspectRatio="xMidYMid meet"><metadata>Created by potrace 1.16, written by Peter Selinger 2001-2019</metadata><g transform="translate scale" fill="currentColor" stroke="none"><path d="M0 1440 l0 -80 1360 0 1360 0 0 80 0 80 -1360 0 -1360 0 0 -80z M0 960 l0 -80 1360 0 1360 0 0 80 0 80 -1360 0 -1360 0 0 -80z"/></g></svg>C skeletal vibrations in the FA ring; this can be done since its framework would not be expected to change significantly after polymerization. Evidently, the IR spectra of dark colored PFA powders are quite different from that of the FA monomer, implying that PFA has a higher degree of π-conjugation with a higher molecular weight. For example, FA monomer exhibits a band at 3039 cm–1 owing to aromatic C–H stretching,26 which becomes weaker and broader in all of the PFAs and is hypsochromically shifted to 3049 cm–1. The zig–zag bands of FA monomer around 1808, 1134, and 939 cm–1 are barely observed in the IR spectra of PFAs because the small π-conjugation within the FA ring has converted into larger π-conjugation along the PFA chains after polymerization. The band at 1438 cm–1 due to CC out-of-plane bending in FA monomer becomes weaker, but is hypsochromically shifted to 1452 cm–1 in PFA. In particular, several typical bands for aromatic compounds at 825, 775, and 746 cm–1 that are attributable to out-of-plane vibrations of adjacent C–H structures in the FA monomer, distinctly become much weaker and broader in the PFAs. All this information confirms the formation of PFA with a large π-conjugated structure and even higher molecular weight produced at the interface between C6H14 and CH3NO2. In addition, by increasing the FeCl3/FA molar ratio from 3 to 9, the IR spectra of PFAs change slightly; however, the 1452 cm–1 band is the strongest for the PFAs synthesized at the FeCl3/FA molar ratios of 7 and 9, suggesting that both PFAs have the largest degree of conjugation and the highest molecular weight, which is verified by The IR spectra for FA monomer and dedoped PFA synthesized with four different FeCl–1 corresponding to the Raman vibration of FA units. Compared with FA monomers,29 these Raman bands generally shift to lower wavenumber, which provides further evidence for PFA formation.The Raman spectrum of the solid microparticles of PFA in Mm/z of 4402 and 10 002 by MALDI/TOF MS as discussed below. The PFA synthesized at 50 °C has lower molecular mass than that at 70 °C since the former has stronger spatial hindrance leading to more difficult chain propagation. As a result, the proposed formulas and macromolecular structures in –6 and 7.4 × 10–2 S cm–1 for as-prepared and iodine doped PFAs, respectively.Elemental analysis results in 3/FA molar ratio of 9, which is a linear polymer. The molecular weight polydispersity index (PDI) of the THF-soluble parts of the PFAs determined by GPC varies from 1.882 to 1.907 to 1.980 to 1.869 to 1.705 when the oxidant/monomer molar ratio is changed from 3 to 5 to 7 to 9 to optimal. It can be concluded that the optimal PFA possesses the highest molecular weight, but the narrowest molecular weight distribution as confirmed by the UV-vis and NMR spectra above. In other words, the PFA achieved under the optimal conditions is really optimal.MALDI-TOF MS is a powerful method for characterizing synthetic polymers, giving the molecular weight of PFAs from 4202, 4402, 4202 to 4402 to 10 002 while changing the oxidant/monomer molar ratio from 3, 5, 7 to 9 to optimal, as shown in 1H–1H COSY and 1H–13C HSQC 2D NMR spectra are powerful methods of analyzing the complicated macromolecular structure of the PFAs containing a large number of very similar protons and carbons. As presented in 1H–1H COSY spectra significantly vary with the oxidant/monomer ratio, displaying six principle coupling peaks in a range between 7.0 and 9.0 ppm, (a) 7.42–8.04 ppm, (b) 8.18–8.58 ppm, (c) 7.72–8.00 ppm, (d) 7.49–8.10 ppm, (e) 7.70–8.20 ppm, and (f) 7.88–8.30 ppm. Interestingly, PFA synthesized at the lowest oxidant/monomer molar ratio of 3 only presents two correlations, i.e., a and c, having 3,4-disubstituted fluoranthene repeat units  and b, having the 1,6-disubstituted fluoranthene repeat unit. When increasing the oxidant/monomer molar ratio from 3 to 7, the appearance of a series of new correlations  implies that the polymers have a mixed chain composition of 3,4- and 1,6-disubstituted fluoranthene units and even other disubstituted fluoranthene units, except that the polymer obtained at an oxidant/monomer molar ratio of 9 is similar to the optimal polymer rather than at an oxidant/monomer molar ratio of 3 because no c correlation is observed in the COSY spectrum of the polymer formed at an oxidant/monomer ratio of 9.at units . The opt13C spectra of PFA, 1H–13C correlations are represented as a contour plot by HSQC experiments. The 1H–13C 2D HSQC spectra consist of several correlation resonances of only the carbons linking protons. According to the earlier discussion of chemical shifts of the protons in the 1H–1H 2D COSY spectra in 1H–13C correlations could be present in the HSQC spectra in 1H–13C correlations of PFA synthesized with an oxidant/monomer molar ratio of 3 are assigned to ρ, β, α, σ. In contrast, the optimal PFA exhibits a different HSQC spectrum, ρ, σ, β, χ.For the assignment of the 1H–1H COSY and 1H–13C HSQC 2D spectra, possible assignments of other aromatic protons and carbons in the polymers are depicted in τ138.7, α136.4, η132.6, θ131.3, χ130.3, ρ128.0, β123.1, σ122.7, φ122.4–122.2. It should be noted that, the chemical shifts of protons and carbons change slightly with the oxidant/monomer ratio. Particularly, the 1H and 13C NMR spectra of the PFA obtained at the oxidant/monomer molar ratio of 3 are relatively simple, but those of the other three PFAs synthesized at the oxidant/monomer molar ratios of 5 to 9 are very complex. It seems that the 1H and 13C NMR spectra of the PFAs obtained at the oxidant/monomer ratios of 5 to 9 are the addition of the spectra of the PFAs synthesized under optimal conditions and at the oxidant/monomer ratio of 3, indicating that the FA polymerization significantly depends on the polymerization conditions. It is interesting to note that the χ protons tend to appear at lower fields from 8.52 to 8.56 to 8.58 ppm when changing the oxidant/monomer molar ratio from 3 to 9 to optimal. On the basis of the macromolecular structure of PFA, it appears that the chemical shifts of the χ protons could be used to evaluate the large π-conjugation of the PFA. That is to say, the polymer with the χ protons located at higher chemical shifts corresponds to higher molecular weight. This indicates that the optimal PFA indeed has the highest molecular weight, which is consistent with the UV-vis spectra demonstrating the strongest band III in Combined with the 3 oxidant solutions are 165 and 1010 mV vs. SCE, respectively. In the first stage, with the drop-wise addition of FA solution, the OCP of FeCl3 solution decreases rapidly from 1010 to 912 mV vs. SCE within the first 20 min because of a fast consumption of the oxidant to form active FA monomer carbonium ions and polymers. The pH of the reaction system also sharply declines from 5.6 to 4.5 due to the production of HCl during the oxidative dehydrogenation of FA monomers. In the second stage between 2 and 18 h after all the FA solution was added, the OCP and pH of the biphasic system further decreased from 883 to 587 mV vs. SCE and 1.45 to 0.92, respectively. Such significant decreases of OCP and pH can be attributed to moderate polymerization between active FA monomers and oligomers to form higher molecular weight polymers, as shown in χ into α positions. This investigation into the OCP and pH of FA polymerization solution strongly suggests that a polymerization time of 20 h is optimal.The OCP and pH variations of the FA polymerization solution with reaction time are shown in 3NO2 does not polymerize in the presence of (NH4)2S2O8, a typical initiator for radical polymerization. The FA polymerization has an oxidative feature because the pH of the reaction solution steadily decreased with reaction time as shown in 3+. At the same time, Fe2+ that resulted from the reduction of Fe3+ was detected. Therefore, we believe that along with the FeCl3 catalyst, CH3NO2 can act as a cocatalyst by forming a H+[FeCl3(CH2NO2)x]– complex that can attack FA monomer to form reactive FA carbonium ions, leading to initiation of the cationic oxidative polymerization of FA. A possible mechanism and reaction intermediates for the cationic oxidative polymerization of FA are proposed in 3. In particular, the polymerization consists of three elementary reactions:The FA polymerization does not appear to follow a radical mechanism because the FA monomer in CH+[FeCl3(CH2NO2)x]– resulting from complexation of FeCl3 with H+(CH2NO2)– originating from a tautomerism between CH3NO2 and H+(CH2NO2)– which in turn acts as a pseudo-acid with a pKa of 10.2, and (b) the difficult formation of FA carbonium ions because no sufficiently reactive FA monomers could be attacked by the H+[FeCl3(CH2NO2)x]– until the temperature was elevated up to 70 °C or the FeCl3/FA ratio was increased to 7. Under either of these conditions dark PFA polymer precipitates formed immediately upon mixing FA monomer in hexane with FeCl3 in nitromethane, and thus, the PFA polymer with both high polymerization yield and high π-conjugation degree can be accomplished, as revealed in (1) Chain initiation involving two steps: (a) fast and easy formation of the Hetc. by inserting FA monomer between the corresponding carbonium ions and counter anion [FeCl3(CH2NO2)x]–, followed by oxidative dehydrogenation condensation in the presence of FeCl3 oxidant at a sufficiently high concentration, leads to (a) dark PFA polymer precipitates formed immediately upon mixing FA monomer with FeCl3 in nitromethane and (b) no significant variation of the π-conjugation degree of the PFA formed with increasing the reaction time from 2 to 24 h, as demonstrated in + released during the oxidative condensation chain propagation of the active oligomer carbonium ions will promote the formation of H+[FeCl3(CH2NO2)x]–, which is beneficial to the formation of more active FA carbonium ions. That is, the FA polymerization possesses self-catalyzing characteristics.(2) Fast chain propagation including dimerization, trimerization, tetramerization, (3) Termination of active PFA carbonium chains by deprotonation.It can be concluded that cationic oxidative dehydrogenation polycondensations are likely in forming the resulting PFAs.+ concentration in the reaction system was 10–0.85 = 0.14 M, i.e., 0.14 M × 50 mL = 7 mmol hydrogen protons were released because of dehydrogenation. Therefore, the average dehydrogenation number in one FA monomer is 7 mmol/3.4 mmol ≤ 2.06, which is close to 2.0 for a helix macromolecular structure of PFA as summarized in On the basis of the steady pH reduction of the polymerization solution shown in 3/FA ratios are shown in d200 0.932 nm, strongest) and 18.96° (d400 0.468 nm), as well as eight very weak peaks at 19.30° (d–204 0.460 nm), 23.96° (d–214 0.371 nm), 20.50° (d004 0.433 nm), 22.20° (d–313 0.400 nm), 22.54° (d113 0.394 nm), 28.62° (d600 0.308 nm), and 38.48° (d800 0.234 nm), while the PFAs show two groups of diffraction peaks at 5.06° (d100 1.744 nm)/10.16° (d200 0.870 nm), and 19.78° (0.448 nm)/24.86° (0.358 nm)/9.38° (0.942 nm)/16.78° (d012 0.528 nm strongest)/19.02° (0.466 nm)/23.6° (0.377 nm), suggesting that there are two kinds of crystalline ordered structures in the PFAs, although they also present a broad diffraction in the region of 15–30° due to an amorphous non-crystalline state of irregular lateral suprastructure of the PFA molecules regardless of the FeCl3/FA ratio used for their synthesis. A series of d100/d200 diffractions indicate that the PFAs have crystalline order that is different from the crystalline structure as FA monomer displaying a series of d200/d400 diffractions because their strongest diffraction peaks are rather different. This crystalline order may be a layered crystalline structure with an interlayer d spacing of 1.744 nm that would be a typical intermolecular π–π stacking distance. It seems that the crystalline diffraction peaks gradually become stronger when the oxidant/monomer molar ratio is decreased from 9 to 0 and finally the FA and PFA obtained especially at the oxidant/monomer molar ratio of 3 have the same diffraction peaks at 9.38° and 19.02°, suggesting that the PFAs consist of FA repeat units and also the FA unit structure was not broken during the oxidative polymerization. It is well known that most chemical oxidative polymers including polypyrrole,32 polyaniline,33 polythiophene,17 and polyfuran34 result in amorphous materials. However, the PFAs synthesized at the biphasic interface between C6H14 and CH3NO2 have a combination of crystalline and non-crystalline structures since the molecular weight of the PFAs synthesized in this study is not high enough. It should be noted that all the PFA powder prepared by various FeCl3/FA ratios illustrates a very weak diffraction around 32° that may be assigned to the characteristic peak of FeCl3,17 although the samples were thoroughly purified before the X-ray diffraction measurements. According to previous reports, the PFA would be able to form a salt (FA unit)2X with an anion of FeCl4–, like the FA monomer.WAXD powder patterns of FA monomer and PFAs synthesized with various FeCl3, forming a very stable dispersion. For example, PFA particles form a uniform red dispersion in ethanol and do not precipitate even after one day of standing. The size distribution of PFA particles prepared with various C6H14/CH3NO2 ratios analyzed by DLS is depicted in Fig. S1b.6H14/CH3NO2 volume ratio from 1/1, 3/2, 3/1, to 50/3, the size of the obtained PFA after 30 min sonication varies from 524 to 217 to 216 to 243 nm, respectively. This has been confirmed by the SEM image in Fig. S1c6H14/CH3NO2 volume ratio of 3/2. In particular, the PFA synthesized in the C6H14/CH3NO2 volume ratio of 3/2 has the diameter and the narrowest size distribution, whereas the PFA synthesized in the C6H14/CH3NO2 ratio of 3/1 has the smallest size. Clearly, the C6H14/CH3NO2 volume ratios of 3/2 and 3/1 are the best to obtain PFA submicron particles. Note that the remarkably different sizes can be mainly attributed to the different dispersion states of PFA particles in water and acetone. That is to say, the dispersion of PFA particles in acetone is much better than in water.PFA particles can be uniformly re-dispersed in DI water, forming a red suspension by sonication, but tending to aggregate after 30 min of standing. The size distribution of the pure optimal PFA particles in DI water was analyzed by LPA in Fig. S1a.3CN, CH3NO2, CHCl3, THF, CH3COOH, and benzene, the PFAs synthesized in this study are only soluble in NMP and DMSO with strong polarity, partly soluble in DMF and 98% H2SO4, and almost insoluble in other solvents. At the same time, the PFAs can disperse very well in HCOOH, CH3CN, CH3NO2, CHCl3, and THF, as mentioned above. The solubility of PFAs also depends on their synthetic conditions. For instance, the PFA synthesized with FeCl3/FA molar ratios of 3, 5, and 9 presents the highest solubility, but PFA synthesized with an FeCl3/FA molar ratio of 7 has a lower solubility possibly due to a higher degree of π-conjugation  than that of FA monomer (363 nm). This implies that the PFA needs much lower energy to excite the fluorescence than FA monomer. Similarly, PFA also exhibits a much longer emission wavelength (peaked at 480 nm) than FA monomer (peaked at 452 nm), indicating that the emission from the PFA is more visual. On the other hand, it can be clearly seen that the emission spectra of all the PFAs show triple bands at 480, 515 and 556 nm due to π* electronic transitions which arise from an average distribution of large π-conjugation lengths of conjugated polymers. The maximum emission wavelength of 10% PFA solution shows an 88 nm red shift as compared with the maximum excitation wavelength, which is close to the 90 nm red shift observed for electropolymerized PFA16 and the 89 nm red shift of FA. The fluorescent intensity of the PFA significantly increases at first and then decreases with augmenting the PFA concentration from 5 to 50 mg L–1, giving the maximum intensity at 10 mg L–1. The excitation and emission spectra of PFA have smaller half-widths and higher maximum excitations and emission wavelengths than the FA monomer. All of this information confirms that PFA has a large π-conjugated structure because the fluorescence properties are greatly improved upon chemical oxidative polymerization of FA.Fluorescent excitation and emission spectra of FA and optimal dedoped PFA solutions in DMSO are shown in 38 Furthermore, the fluorescence of PFA largely depends on the FeCl3/FA ratio in Fig. S2 (middle),3/FA molar ratio of 7 emits the brightest fluorescence. This implies that the PFA obtained at the FeCl3/FA molar ratio of 7 has the largest degree of conjugation, as confirmed earlier. With increasing PFA concentration from 5 to 500 mg L–1, the solution of the optimal PFA first emits an increased and then a decreased fluorescence, realizing the strongest fluorescence at 25 mg L–1, which can be seen in 2SO4 or excitation at 254 nm. This excellent fluorescence and its sensitivity to PFA concentration are very important for its potential applications in OLEDs and other optoelectronic devices.As expected, in agreement with the fluorescence spectra, distinct fluorescence differences between FA and PFA in DMSO under a 365 nm UV light are observed. In sunlight, the FA and PFA solutions in 2+, Fe2+, Co2+, Ni2+, Cu2+, and Hg2+, but is almost completely quenched only by Fe3+ at the same ion concentration of 3125 μM in 2+ (≤50 μM) on the fluorescent emission of optimal PFA solution containing 5 μM Fe3+ is less than 3.42%. Similarly, the interference of coexisting Cu2+ (≤1000 μM) on the emission of optimal PFA solution containing 500 μM Fe3+ is less than 5.28%, as shown in 2+ at ≥2000 μM would interfere with the emission of optimal PFA solution containing 500 μM Fe3+ to some extent. All these examples indicate that the selectivity of the PFA toward Fe3+ over the other six ions is extraordinarily high as long as the other six ions do not have a concentration four times higher than Fe3+. This suggests that PFA definitely has high selectivity toward Fe3+ over the other six ions. Note that (F0/F) – 1 increases significantly and nonlinearly with Fe3+ concentration, indicating that energy transfer along the PFA π-conjugation enlarges the quenching degree of Fe3+.393+ is red-shifted by about 15 nm, indicating a strong interaction between Fe3+ and PFA chains. Log(F0/F) vs. Fe3+ concentration illustrates a good linear relationship with a correlation coefficient (R) of 0.9982 over a wide Fe3+ concentration range of 0.313 to 6250 μM with a detection limit down to 62.5 nM, producing the equation log(F0/F) = 0.6233[Fe3+] – 1.977  at the maximal weight-loss rate ((dα/dt)m) rises from 510 to 557 °C, with corresponding (dα/dt)m decreases from 0.303 to 0.219% min–1. Meanwhile, the PFA obtained with a FeCl3/FA molar ratio of 7 demonstrates the highest Tdm of 576 °C and the second lowest (dα/dt)m of 0.231% min–1. This information confirms the great advantages of using chemical oxidative polymerization to facilely synthesize high quality PFA with higher purity, higher carbon yield, and higher thermo- and chemo-resistances than electropolymerization. For example, the electropolymerized PFA exhibits a high impurity content up to 14.6%, low Tdm down to 442 °C, and char yield down to 23.5% at 727 °C, respectively.16 In addition, the high molecular weight PFA obtained by the cost-effective chemical oxidative polymerization of FA is even more thermally stable than most typical heat-resistant polymers, except for expensive polybenzazole43 and poly(p-phenylene benzobisthiazole) (PBT)44 46 which share similar structures with PFA. Note that the conductivity can be further enhanced by thermal treatment of pristine PFA at high temperature. Three carbonized samples in nitrogen at up to 985 °C have much higher conductivities of 5.2, 8.5, and 11.6 S cm–1 for the PFAs (a), (b), and (c), respectively (–1 with a carbon yield of 50%. The well developed structure of these highly conducting carbon particles has been confirmed by two typical Raman bands of carbon: the strongest band at 1306 cm–1 and the sharpest Raman band at 1584 cm–1 due to D- and G-bands, as shown in The bulk electrical conductivity of the PFA particles is strongly influenced by the polymerization conditions and their doping states although FA monomer is an insulator in any state. The conductivity of pristine PFA significantly varies with the FeClectively . Surpris6H14 and CH3NO2 using FeCl3 as catalyst and oxidant. The effects of the polymerization parameters including polymerization medium, C6H12/CH3NO2 ratio, method of oxidant/monomer mixing, oxidant/monomer ratio, polymerization temperature and time on polymerization yield, macromolecular structure, particle size distribution, solubility, solvatochromism, electrical conductivity, fluorescence, and thermal properties have been systematically optimized. Optimal synthesis of PFA possessing the highest polymerization yield up to 94%, most extensive π-conjugation, highest molecular weight, and highest electrical conductivity can be obtained as follows: drop-wise addition of FA solution to FeCl3 solution, C6H12/CH3NO2 volume ratio of 3/2, polymerization temperature of 70 °C, polymerization time of 18 h, and FeCl3/FA molar ratio of 7. This polymer exhibits a wide range of controllable conductivity from 7.1 × 10–8 S cm–1 to 150 S cm–1, good solubility, unique solvatochromism, high thermostability and relatively high char yield at 985 °C. In particular, this polymer exhibits excellent visible skyblue fluorescence emission and high selective response for detecting Fe3+ with a detection limit down to 62.5 nM because of the synergistic effect of well-distributed π-conjugated electrons throughout the polyfluoranthene which function as both the fluorophore and the receptor units simultaneously, avoiding complicated multistep procedures of other superamplified fluorescent polymers that usually contain bulky fluorophore groups and specific receptors. This new PFA is a promising material for use as a strongly fluorescent emitting organic material and a selectively sensitive Fe3+ chemosensor, an organic semiconductor, and a cost-effective carbon precursor.We have synthesized multifunctional polyfluoranthenes with a helical configuration by a facile cationic oxidative polymerization of fluoranthene at the interface between C


Fusicoccum amygdale, causes the inhibition of ABA-induced stomatal closure. The mechanism of inhibition is remaining unclear. We analyzed the role of hydrogen peroxide (H2O2) and relationship between H2O2 removal and cytosolic pH changes during inhibition of ABA-induced stomatal closure by FC.Fusicoccin (FC), a fungal phytotoxin produced by 2O2 production and stomatal closure, but FC inhibited the effects of ABA on these two parameters. Treatment with catalase (CAT) and NADPH oxidase inhibitor diphenylene iodonium (DPI) mimicked the effect of FC. These data suggest that inhibition of ABA effect by FC is related to the decrease of H2O2 levels in guard cells. Furthermore, similar to CAT, FC not only suppressed stomatal closure and H2O2 levels in guard cells treated with exogenous H2O2, but also reopened the stomata which had been closed by ABA and reduced the level of H2O2 that had been produced by ABA, indicating that FC causes H2O2 removal in guard cells. The butyric acid treatment simulated the effects of FC on the stomatal aperture and H2O2 levels in guard cells treated with exogenous H2O2 and had been closed by ABA, and both FC and butyric acid reduced cytosolic pH in guard cells of stomata treated with H2O2 and had been closed by ABA, which demonstrate that cytosolic acidification mediates FC-induced H2O2 removal.According to the results, ABA treatment induced H2O2 removal and reduces H2O2 levels in guard cells, finally inhibits stomatal closure induced by ABA.These results suggest that FC causes cytosolic acidification in guard cells, then induces HThe online version of this article (doi:10.1186/1999-3110-55-33) contains supplementary material, which is available to authorized users. Abscisic acid (ABA) is a phytohormone that plays vital roles in the control of growth and development and is involved in the response to various environmental stresses. ABA has been demonstrated to affect leaf size, shoot growth, stomatal and lateral root development , a fungal phytotoxin produced by 2O2 production and partially blocks both blue light- and FC-dependent activation of H+-ATPases by decreasing in phosphorylation of H+-ATPase via H2O2  was obtained from Biotium . The fluorescence probes of 2′,7′-bis(2-carboxyethyl)-5n-carboxy fluorescein-acetoxy methyl ester (BCECF-AM), ABA, fusicoccin (FC), catalase , diphenylene iodonium (DPI), DMSO, Pluronic F-127, MES and butyric acid were purchased from Sigma-Aldrich . Unless stated otherwise, the remaining chemicals were of the highest analytical grade available from various suppliers of Chinese companies.Molecular probes 2′,7′-dichlorodihydrofluorescein diacetate (HVicia faba L.) was grown in a controlled-environment plant growth chamber with a humidity of 80%, a photon flux density of 300 μmol m-2 s-1PAR generated by cool white fluorescent tubes , and an ambient temperature 25 ± 2°C with a 14-h light and 10-h dark cycle. The epidermis was peeled carefully from the abaxial surface of the youngest, fully expanded leaves of 4-week-old seedlings, and cut into pieces about 5 mm width and 5 mm lengths.Broad bean  with FC, CAT or DPI for 3 h with ABA under light conditions (300 μmol m-2 s-1) at 25 ± 2°C. Final stomatal apertures were recorded with a light microscope and an eyepiece graticule previously calibrated with a stage micrometer. To study the effects of FC, CAT and butyric acid on stomatal closure caused by exogenous H2O2, epidermal strips were incubated in MES/KCl buffer with H2O2 alone, or containing FC, CAT and different concentrations of butyric acid for 3 h, and then the stomatal apertures were recorded. To study the effects of FC, CAT and butyric acid on stomata that had been closed by ABA, strips were incubated in MES/KCl buffer for 3 h with ABA and were then treated with fresh buffer alone, or containing FC, CAT and different concentrations of butyric acid for another 1 h, final stomatal apertures were recorded.Stomatal apertures were monitored by the method of McAinsh To avoid any potential rhythmic effects on stomatal aperture, experiments were always started at the same time of the day. In each treatment, we scored 30 randomly selected apertures per replicate and treatments were repeated three times. The data presented are the means of 90 measurements ± s.e.2O2 content and cytosolic pH of guard cells were monitored with H2DCF-DA and BCECF-AM, respectively, as previously described  or 20 μM BCECF-AM (10 min), in Tris–KCl loading buffer  containing 0.05% Pluronic F-127 in the dark at 25 ± 2°C. In experiment involving time-course monitoring of H2O2 levels and cytosolic pH in guard cells, the epidermal strips were treated with ABA for 3 h and then with FC for another 10, 20, 30, 40, 50, or 60 min before loading with probes.The epidermal strips were treated as described for stomatal bioassay section, and were then loaded with 50 μM H2O2 content in guard cells of Vicia faba . Images acquired from the confocal microscope were analysed with Leica image software and Photoshop. To enable the comparison of changes in signal intensity, confocal images were taken under identical conditions  for all samples, and in each treatment we measured three epidermal strips, and the treatment was repeated three times. The selected confocal images represented the same results from three replications.After excess dye was washed off with fresh Tris–KCl loading buffer in darkness, TCS SP5 laser-scanning confocal microscopy  was used to measure cytosolic pH or HStatistical analyses were performed by using a one-way ANOVA followed by the least significant difference (l.s.d.) test.V. faba was incubated in different concentrations of FC with 10 μM ABA. As shown in Figure M obviously inhibited ABA-induced stomatal closure, so 0.1 μM FC was used in the following experiments.Previous studies have shown that FC, a fungal phytotoxin, causes irreversible stomatal opening  and DPI (an inhibitor of H2O2–generating enzyme NADPH oxidase), respectively. The results show that CAT significantly inhibited ABA-induced stomatal closure in a dose-dependent manner . DPI, an inhibitor of H2O2-generating enzyme NADPH oxidase, had no obvious effect on exogenous H2O2-induced stomatal closure    Figure C and mar) Figure D. The re2O2 had been generated by ABA in guard cells.Both FC and butyric acid reopen the stomata had been closed by ABA and reduce the level of H2O2 removal, we also compared the effects of FC with CAT on the closed stomata induced by ABA and the level of H2O2 generated by ABA. As shown in Figure 2O2 having been generated by ABA, thus resulting in stomatal reopening.To further ascertain whether or not FC induces H2O2 that had been generated by ABA in guard cells was also measured in the present studies. After an incubation of 3 h in MES/KCl buffer in ABA, the strips were treated with fresh MES/KCl buffer alone, or containing FC and CAT for another 1 h, and then were loaded with H2DCF-DA, washed, and examined by laser scanning confocal microscopy. As shown in Figure 2O2 removal, hence reduces the level of H2O2 induced by ABA in guard cells.The effect of FC on the level of H2O2 in guard cells, the effects of butyric acid on the stomata had been closed by ABA and the level of H2O2 had been generated by ABA were measured. Figure P < 0.05)   Figure C, and ma) Figure D. The re2O2 and stomata had been closed by ABABoth FC and butyric acid reduce cytosolic pH in guard cells treated with exogenous H2O2 removal, we measured the effect of FC on cytosolic pH in guard cells during ABA-induced stomatal closure, and the effects of FC and butyric acid on BCECF-AM fluorescence in guard cells treated with exogenous H2O2 and guard cells of stomata had been closed by ABA. As shown in Figure P < 0.05), and ABA-induced increase of cytosolic pH was largely prevented by FC (P < 0.05) , FC, cytokinins, low COA Figure  and larg2O2 in cultured sycamore and Arabidopsis thaliana cells (Beffagna and Lutzu et al. 2O2 production of tobacco cells (Simon-Plas et al. 2O2 levels in stomatal guard cells. The question arises of how FC reduces H2O2 levels in guard cells. Our results show that FC suppressed exogenous H2O2-induced stomatal closure and H2O2 levels in guard cells treated with exogenous H2O2 (Figure 2O2 that had been generated by ABA (Figure 2O2. These results prove that the treatment with FC induces the removal of H2O2 within guard cells, thereby prevents stomatal closure induced by exogenous H2O2, and causes the reopening of the closed stomata by ABA. Together with the facts that FC inhibits stomatal closure induced by ABA (Figure 2O2 levels in guard cells caused by ABA (Figure 2O2 levels in guard cells via inducing H2O2 removal, eventually preventing stomatal closure induced by ABA.Previous reports demonstrated that FC stimulates production of H2 Figure A,B, and A Figure A,B. The A Figure A,B, a scA Figure A and redet al. et al. et al. et al. et al. et al. et al. et al. 2O2 levels (Song et al. 2O2 levels in FC-inhibited stomatal closure. In this study, we provide evidence that, similar to butyric acid, FC not only reduced cytosolic pH caused by ABA in guard cells (Figures 2O2 removal (Figures 2O2 removal induced by FC. Real-time monitoring with the help of fluorescent dyes BCECF-AM and H2DCF-DA revealed that FC-induced decrease of cytosolic pH faster than that of H2O2 levels and confirmed that acidification of guard cell could be upstream of H2O2 during inhibition of ABA-induced stomatal closure by FC (Figure 2O2 levels (Figure 2O2 removal via reducing cytosol pH, hence lessens H2O2 levels in guard cells during ABA-induced stomatal closure. It is an intriguing problem about how FC-induced cytosolic acidification causes H2O2 removal, and we suppose that some H2O2-scavenging mechanism might be activated, including change of ASA redox state, catalase or ascorbate peroxidase activities (Beffagna and Lutzu Cytosolic pH is an important factor in the regulation of stomatal movement (Suhita  Figures  and 7 bu Figures , which sC Figure . CombineC Figure D and H2O2O2 removal and reduces H2O2 level via reducing cytosol pH in guard cells, thus inhibiting ABA-induced stomatal closure.In summary, these data suggest that FC induces H


Jahn–Teller distortions are observed in Au25(SR)18 by single crystal X-ray crystallography. SQUID magnetometry, DFT theory, and linear optical spectroscopy corroborate the finding. 25(SR)18. We present the single crystal X-ray structures of the previously undetermined charge state Au25(SR)18+1, as well as a higher quality single crystal structure of the neutral compound Au25(SR)180. Structural data combined with SQUID magnetometry and DFT theory enable a complete description of the optical and magnetic properties of Au25(SR)18 in the three oxidation states. In aggregate the data suggests a first-order Jahn–Teller distortion in this compound. The high quality single crystal X-ray structure enables an analysis of the ligand–ligand and ligand–cluster packing interactions that underlie single-crystal formation in thiolate protected metal clusters.The relationship between oxidation state, structure, and magnetism in many molecules is well described by first-order Jahn–Teller distortions. This relationship is not yet well defined for ligated nanoclusters and nanoparticles, especially the nano-technologically relevant gold-thiolate protected metal clusters. Here we interrogate the relationships between structure, magnetism, and oxidation state for the three stable oxidation states, –1, 0 and +1 of the thiolate protected nanocluster Au The Jahn–Teller theorem establishes that molecular orbitals must be symmetrically occupied by electrons in order for them to be energetically degenerate.25(SR)18 in 3 charge states. Of the compounds comprising the Aux(SR)y monolayer protected cluster magic number series,25(SR)18 nanocluster25(SR)18 formulation made subsequently by Tsukuda.For nanocluster compounds  the role of the Jahn–Teller effect is unclear. In this work, we investigate the structural and magnetic properties of Au25(SR)18 and many other Aux(SR)y compounds as large as Au102(SR)44 are well predicted by a spherical superatom model.25(SR)18–1 is an 8e– system, corresponding to a noble gas-like 1S21P6 superatom electron configuration. The superatom electron configuration of Au25(SR)18 can be modified through now well established electrochemical methods which allows for stable preparations of Au25(SR)18 in –1, 0 and +1 oxidation states, corresponding to 1S21P6, 1S21P5, and 1S21P4 superatom electron configurations, respectively. Several properties including magnetism, optical absorption, catalytic reactivity and stability can be rationalized in terms of superatom electron configuration.25(SR)18 is subject to Jahn–Teller effects.Theoretical studies conclude that the frontier orbitals of Au25(SR)18, then Hund's rule predicts that the –1, 0, and +1 charge states should be diamagnetic, S = 1/2 paramagnetic and S = 1 paramagnetic, respectively. However, if the cluster has morphological flexibility and can change shape with changing charge, then the superatomic orbitals may lose their degeneracy with changing charge states and the –1, 0 and +1 charge states would become diamagnetic, S = 1/2 paramagnetic, and diamagnetic, respectively. The magnetic properties of thiolate protected gold nanoparticles, however, are controversial, with inconsistent reports of magnetic properties made for apparently similar preparations.25(SR)18 there are conflicting reports of magnetism. Of three prior reports interrogating Au25(SR)18 magnetism by EPR or NMR spectroscopy, all reports found that the –1 and 0 oxidation states are diamagnetic and S = 1/2 paramagnetic, consistent with superatom theory for the cluster. There are conflicting reports, however, regarding the nature of the +1 cluster, with two studies concluding diamagnetism and one study concluding paramagnetism.If Jahn–Teller effects do not apply to Au25(PET)18 in its three stable charge states. Notably we present the first crystal structure of {[Au25(PET)18+1][PF6–1]}, as well as a notably higher resolution crystal structure of Au25(PET)180 relative to a previous report.Th.21P6 to 1S21P4. The evolution of structure, magnetism and optical properties with oxidation state can be understood in terms of Jahn–Teller effects.Here we present a comprehensive study on the structures, magnetic properties, and optical properties of Au25(PET)18–1 was synthesized by minor modification of a previously reported protocol.4·3H2O and 1.56 g (2.85 mmol) of tetraoctylammonium bromide (TOAB) were dissolved in 70 ml of THF. This solution stirred for 15 min turning color from yellow to orange. 1.8 ml (13.4 mmol) of 2-phenylethanethiol (PET) was added. The reaction mixture stirred until turning clear, approximately 3 hours. A freshly prepared aqueous solution containing 965 mg (25.5 mmol) NaBH4 and 24 ml of water at 0 °C was rapidly added under vigorous stirring. Stirring continued for 2 days, in a covered  flask. The reaction mixture was dried, giving an oily product. The crude product was sonicated in methanol resulting in precipitation of the Au25(SR)18–1. The precipitate was collected by centrifugation and washed four times with methanol. Crystals of Au25(PET)18–1 were formed by dissolving Au25(PET)18–1 and TOAB in toluene and adding ethanol just until a precipitate forms and is collected by centrifugation. The precipitate is examined for the optical signature of Au25(SR)18–1. Additional fractions of ethanol are added until the precipitate contains Au25(PET)18–1. Au25(PET)18–1 can be oxidized to the Au25(SR)180 by shaking in the presence of silica gel. Crystals of Au25(PET)180 were formed in the same way as Au25(PET)18–1, except TOAB was not added to the solution.Au25(PET)18+1 prepared by bulk electrolysis from crystallized Au25(PET)18–1. Au25(PET)18–1 was dissolved in 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) in dichloromethane (DCM). Bulk electrolysis was preformed at constant potential in a three-compartment cell at 300 mV vs. SCE. Immediately following electrolysis, the solution was taken for crystallization, as the lifetime of Au25(SR)18+1 is limited. Ethanol was added to the DCM solution used in bulk electrolysis until a precipitate formed that was collected by centrifugation. Dissolution in DCM followed by ethanol precipitation was repeated until Au25(PET)18+1 was isolated as judged by UV/Vis. The solution appears green. Au25(PET)18+1 can be stored as a dry precipitate at –20 °C. Crystals of –1/0/+1 oxidation states were determined by single crystal X-ray methods.AuWe performed density functional theory (DFT) calculations using the GPAW package that implements projector augmented-wave (PAW) method in a real-space grid.25(PET)18+1 and an improved Au25(PET)180 crystal structure.25(PET)18–1/0/+1 18 as shown in We quantified the distortions from ideal symmetry in two ways: first, by analysis of bond lengths, angles, and dihedral angles; second, by continuous symmetry measure (CSM)25(PET)18 is composed of 4 shells of symmetrically related atoms  atoms of Au25(SR)18 forming the vertices of an irregular polyhedron. This polyhedron can be considered as a dodecahedron missing 8 vertices. The missing 8 vertices inscribe a cube within the dodecahedron. The outermost shell  atoms of shell III, in addition to being chemically bonded to II and IV, also face-cap 12 of the 20 faces of shell I. The S12 geometric icosahedron of shell II is distorted from the ideal shape in a manner consistent with its chemical bonding to shell III.The geometric relationships of the shells to each other is as follows: the SI to be a nearly perfect icosahedron for Au25(PET)18–1. Increasing the oxidation state of Au25(PET)18 from the 8e– superatom anion to 7e– neutral and 6e– cationic oxidation states results in distortion of shell I. CSM values for shell I relative to an ideal icosahedron are 0.067, 0.201 and 0.524 for the –1, 0 and +1 oxidation states, respectively. Bonds lengths for shell I, which in an ideal icosahedron are identical, vary over a range of 0.3 Å, 0.4 Å and 0.7 Å for Au25(PET)18–1, Au25(PET)180, and Au25(PET)18+1, respectively. The variation in bond lengths is shown in a quantitative heat map of the icosahedral cores of each charge state in CSMI are also observed in shell II. The CSM values for shell II are 3.407, 3.879, and 4.45, for –1, to 0, and +1, respectively. For shell III the CSM values are 0.108, 0.092, and 0.155, for –1, 0 and +1, respectively. The CSM values for shell IV are 0.138, 0.109, and 0.106, for –1, 0, and +1.The geometric distortions from IV is apparently least affected by charge state, as it is almost ideally octahedral for 0 and +1, while –1 shows the largest deviation from this symmetry. We attribute the deviation from ideal symmetry in shell IV for the anion to the packing of the tetraoctyl ammonium cation in the crystal lattice. In the case of Au25(PET)18+1, the lattice position of the PF6– ion does not cause deviation from ideal symmetry in shell IV.The outer-most shell II–IV), we elaborate how each shell distorts with respect to shell I. The symmetry of the inorganic core (shells I–IV) is approximately of the point group D2h.25(SR)18, there is some deviation from this idealized description. The amount of symmetry lowering, on average, increases with increasing oxidation state. As Au25(PET)18 becomes more oxidized the gold atoms in shell III shift toward the edges of shell I in order to stabilize the longer/weaker bonds that arise from distortion of the icosahedron. As shown in ESI Table S4III deviate away from the face are 1.91°, 2.06°, and 2.63° for –1, 0, and +1 charge states, respectively. As a consequence of the distortion of the underlying structure, atoms in shells II and IV bend out of the plane defined by the D2h point group.To fully describe the changes that occur to the semi-rings , followed by –1 (3.9°), and finally 0 (0.8°) oxidation states. Thus, the coordinates of atoms in shell IV appear to be influenced by a combination of counterion, solvent, and underlying inorganic structure.The deviations from ideal symmetry of 25(PET)18 depends on the superatomic electron configuration,II and III.We previously reported that the thermal stability of Au25(PET)18 evolves notably across each charge state, suggesting changes in the underlying electronic structure after oxidation or reduction of Au25(SR)18. The absorption peak around 680 nm (1.81 eV) is attributed to the transition from the 1P to 1De and the peak between 450–470 nm (2.76–2.58 eV) has been attributed to the transition of the 1P to 1Dt.e orbital. The energy transition from the 1P to 1De for the –1, 0, and +1 are 1.78 eV, 1.81 eV, and 1.88 eV, respectively. For the 1P to 1Dt energy gaps of 2.76 eV, 2.68 eV, and 2.58 eV are observed for the –1, 0 and +1, respectively. Finally the energy gap for ligand band to superatomic D orbital transition is 3.08 eV for –1 and 0, and 3.15 eV for +1. These values are summarized in ESI Table S7.The absorption spectra of Au25(PET)18 are previously reported.25(PET)18–1 the 1P to 1De transition shows a slightly decreased energy gap of about 0.03 eV for Au25(PET)180, while the energy of this transition increases for Au25(PET)18+1 by approximately 0.1 eV. The decrease in the HOMO–LUMO energy gap from Au25(PET)18–1 to Au25(PET)180 is due to one of the 1P orbitals increasing in energy, but still being occupied by one electron, depicted in a qualitative energy level diagram in t going from with increasing oxidation of Au25(PET)18 can be attributed to the splitting of the superatomic D orbital degeneracy. This first-order Jahn–Teller distortion is reflected in the distortion from ideal symmetry in the crystal structures.e in Au25(PET)18+1 arises from the electron deficient core pulling electron density from the ligand shell. This is supported by the shorter average bond lengths between sulfur and shell I Au atoms in Au25(PET)18+1.The experimental and theoretical spectra of AuTheoretical optical absorption spectra Fig. S9 show a q25(SR)18–1/0/+1 cluster by Superconducting Quantum Interference Device (SQUID). Relative to NMR and EPR approaches SQUID incorporates greater sensitivity, allowing observation of smaller molar magnetic susceptibilities (χm). SQUID measures the total susceptibility of a sample whereas previous studies were limited to paramagnetic susceptibility. Subtraction of the diamagnetic contribution from χm allows determination of the paramagnetic susceptibility (χp). χp can be used for the comparison of a magnetic moment to that of a free electron. The diamagnetic susceptibilities were approximated from Pascal's diamagnetic corrections.We report the first investigation of magnetism in the Au25(SR)18, temperature was ramped from 4 K to 300 K under a magnetic field of 0.1 Tesla. In this regime, paramagnetic substances show a response that is inversely proportional to the temperature, and diamagnetic substances show a temperature-independent response. χpvs. temperature. We conclude that Au25(PET)18 in –1 and +1 oxidation states is almost ideally diamagnetic. This observation agrees with the computational prediction for the spin-singlet ground state of Au25(PET)18+ (the spin-triplet state is predicted to be +0.39 eV higher in energy). Deviations from ideal behavior are reflected in a very small paramagnetic-type response, observable only at very low temperatures for –1 and +1. Conversely, Au25(PET)18 as a neutral compound produces a nearly ideal paramagnetic response that could be observed up to 300 K. The paramagnetic susceptibilities found from SQUID for Au25(SR)18–1/0/+1 correspond to 0.01, 1.07, and 0.03 unpaired electrons, respectively.To determine the charge dependent magnetic behavior of Au25(PET)180 fits the Brillouin function for a spin value of 1/2 and a g-factor of 2.16, as shown in Fig. S5.g-factor value indicates spin–orbit coupling, similar to a previous conclusion for this system.These values assume ideal paramagnetic behavior, where magnetic anisotropy or magnetic coupling violate the assumption. To determine magnetic anisotropy, measurements were made at low temperatures (2–32 K) and large magnetic fields (1–5 T). Under these conditions, the unpaired electrons within a paramagnetic substance all align with the external field and response is expected to fit to the Brillouin function of magnetism.25(PET)18. However, some paramagnetic susceptibility is observed that is not accounted for by this simple approximation. Previous studies have reported that the gold 5d orbital is partially depleted in its bonding to sulfur.25(SR)18 molecule is observed as a small magnetic moment for the –1 and +1 oxidation states.First order Jahn–Teller distortions resulting in the splitting the degeneracy of superatom P orbitals account well for the magnetic behavior of Au25(PET)18–1, Au25(PET)18+1 has a slightly larger magnetic susceptibility. We propose that this arises from greater electron deficiency in Au25(PET)18+1, which pulls electron density inward, creating larger d holes in the semiring Au(i) atoms compared to Au25(PET)18–1. According to the Bader charge analysis, 0.34e and 0.28 are depleted from the core and semiring Au atoms, respectively, when comparing Au25(PET)18+1 to Au25(PET)18–1 (Table S625(PET)180 is more complicated. Here we propose that due to the almost degenerate P orbitals, the paramagnetic susceptibility in excess of 1.0 unpaired electrons arises from spin–orbit coupling.25(PET)180. Our values for magnetism in the anionic compound are consistent with previously reported results.32Compared to Au Table S6. The mag25(SR)18–1/0/+1, there are substantial differences in the ligand shell structure in the solid state for each charge state. These differences in the ligand layer do not appear to be propagations of the changes in the inorganic core due to charge state; rather, the differences in the ligand layer of Au25(SR)18–1/0/+1 arise from different inter- and intra-molecular ligand–ligand interactions, ligand–counterion interactions, and ligand–solvent interactions 18+1 structure reported here allows a careful analysis of the role of phenylethane thiolate ligands in the packing of Au25(PET)18+1 into single crystals. To our knowledge, no similar analysis has been previously reported; the interactions described here, however, appear to be ubiquitous among PET protected AuNC structures.The high quality of the AuP1(bar) space group, there are nine crystallographically independent PET ligands found on the cluster surface (25(SR)18+1 crystal structure.Due to the imposed inversion symmetry of the  surface  located anti or gauche conformation on the cluster surface, corresponding to an S–CH2–CH2–Ph torsion angle of ∼180° or ∼60°, respectively  fold over the semiring to which they are bonded and form cation–aromatic interactions with the AuI atom in the semiring. Specifically, AuI···π interactions are observed, with average distance of 3.43 Å  does not form cation–phenyl interaction with the AuI atom in the unit. Instead it coordinates to the PF6– counter anion and DCM solvent molecule that sit above the corresponding AuI atom (Au3), preventing the AuI···π interactions observed for other gauche ligands.Each ligand adopts either ectively . Four ofÅ Fig. S3. A fifth25 clusters. In addition, these ligands form intermolecular Ph···F, Ph···Cl and CH···F interactions with the PF6– anions or DCM solvent molecules within the crystal lattice.The remaining four crystallographically independent ligands  form inter-cluster CH···S, CH···Ph and Ph···Ph interactions with the ligands of adjacent Au25(PET)18+1 clusters. A packing diagram for the crystalline arrangement of clusters is shown in Fig. S3.6–DCM–PET construction. An example of each of these interactions is shown in We observe three structural motifs that underlie the intermolecular interactions among adjacent Au25 cluster by forming π···π and CH···π inter-cluster interactions  interactions with PET5′ and PET6′ ligands and CH···π (2.85 Å) interaction with PET7′ ligand. In the phenyl–phenyl′ square assembly, PET9 ligands interact with the respective ligands of the neighboring Auractions , panel A25 clusters, and also with the PF6– anion and DCM solvent molecule  interactions with the neighboring PET6′ and PET9′ ligands, respectively. In addition to the aromatic interaction, the PET5 ligand quite interestingly also forms PhH···S (2.92 Å) interaction with the sulfur atom of the neighboring PET9′ ligand. The PET8 ligand of the nucleating cluster, on the other hand, connects to a second neighboring Au25 cluster by forming perpendicular edge-to-face π···π (2.83 Å) interaction with its PET1′′ ligand. The space between the two neighboring Au25 clusters is occupied by the DCM–PF6–PF6–DCM complex (vide infra) and in addition to the prevailing aromatic inter-cluster interactions, PET2 ligand is also available to form π···HC (2.90 Å) and PhH···F (2.60 Å) interactions with the solvent DCM and PF6– anion, respectively.The extended π-interaction network is nucleated by three PET ligands  in the anti-conformation, which are located at the S2–S5–S8 intersection of the three separate semirings Fig. S2. These l25(PET)18 nuclei in the single crystal are occupied by a DCM–PF6–PF6–DCM complex that not only fills the available space, but also coordinates to the neighboring PET ligands  forming directional aromatic–halide and aromatic–CH weak inter-cluster interactions 18 in three discrete charge states allows for the first time a comparison of electronic and magnetic differences of all three stable charge states of Au25(SR)18 in the context of their structure. The Jahn–Teller effect is a convenient structural framework to describe the evolution of structure as oxidation state changes. Au25(PET)18–1 has a noble gas-like configuration (1S21P6) underlying its diamagnetism and comparatively high thermal stability. Comparatively, Au25(PET)180 with 1S21P5 superatom electron configuration is paramagnetic arising from an unpaired 1P electron. When incomplete, the superatomic 1P become non-degenerate, which is reflected in the structure of the cluster becoming oblate relative to the anion. Oxidation to Au25(PET)18+1 (1S21P4) results in larger distortions to the cluster than are observed in either of the other charge states. The electronic distortion results in an unoccupied P orbital in Au25(PET)18+1, rendering it diamagnetic. Here we show for the first time that Jahn–Teller effects apply to thiolate protected gold clusters. The superatom driven distortions are primarily observed in the 13 gold atoms of shell I, with subsequent shells reflecting smaller distortions. A Jahn–Teller effect for Au24X(SR)18 where X = Pd or Pt was recently reported by another group, based on spectroscopic evidence, while this paper was under revision.39The determination of the crystal structures of AuSupplementary informationClick here for additional data file.Crystal structure dataClick here for additional data file.