However, the rate of Hcy oxidation increased by up to 150 fold in the presence of CB[7], as suggested by the DTNB assay. Thus, supramolecular complexation under basic pH conditions led to the formation of a HSSH-CB[7] complex, and not Hcy-CB[7]. The results indicate that Hcy is rapidly oxidized to HSSH under the catalysis of CB[7], which acts as a reaction chamber, in basic pH conditions. Our studies suggest that Hcy concentration, a risk factor for cardiovascular disease, can be selectively and more easily quantified by supramolecular complexation with CB [7].We report the effect of pH on the supramolecular complexation of two biothiols, viz., homocysteine (Hcy) and cysteine (Cys), with cucurbit[7]uril (CB[7]). Under basic pH conditions, Cys did not complex with CB[7], whereas Hcy efficiently complexed with CB[7], as confirmed by  Biothiols are a class of substances that play a vital role in the maintenance of life by means of an equilibrium that exists between their reduced free thiol and oxidized disulfide forms in biological systems . The int48n]uril (CB[n]), where n indicates the number of glycoluril units , is an interesting supramolecule composed of glycoluril (=C4H2N4O2=) monomers linked by methylene (-CH2) bridges. All CB[n] structures have the same cavity depth, but the cavity size differs according to n [n] molecules have specific binding properties for small biomolecules, peptides, and proteins depending on the cavity size , iodoacetamide, ammonium acetate , 100 mM PBS buffer (pH 7.5), 100 mM borate buffer (pH 8.0–8.5), and 100 mM Tris-HCl buffer (pH 8.8), respectively. To determine the Cys-CB[7] and Hcy-CB[7] binding ratios, 10 μl volumes of 500 μM Cys (5 nmol) and 500 μM Hcy (5 nmol) were reacted separately with 50 μl of CB[7] (100 nm) for 5 min. Then, each sample was mixed with 120 μl of the DTNB solution. Another batch of Cys/CB[7] or Hcy/CB[7] samples was reacted with iodoacetamide at pH 6.0 and 8.8, and then mixed with 120 μl of the DTNB solution. The absorbances of the resulting solutions were measured at 412 nm using a spectrophotometer  after 3 min of reaction with DTNB. Iodoacetamide (100 nmol) is a thiol-blocking electrophilic reagent that was used as a negative control.The time-dependent changes in the Cys and Hcy solutions without CB[7] were also studied using the DTNB assay under different pH conditions for the analysis of autoxidation. Cys (500 μM) and Hcy solutions (500 μM) were incubated at 30°C for 3, 6, 9, 12, 18, 24, and 36 h under pH 6.0 and 8.8 conditions. Thereafter, 10 μl of the incubated 500 μM Cys or 500 μM Hcy solution was mixed with 70 μl of the sodium phosphate buffer (pH 6.0) and Tris-HCl (pH 8.8), respectively. Subsequently, the resulting solution was reacted with 120 μl of 2 mM DTNB for 3 min, and then the absorbance at 412 nm was recorded. All the experiments were performed at 25°C.p < 0.05 was considered statistically significant.The data were analyzed with SPSS version 28.0.1.0 0  using one-way ANOVA and post-hoc comparisons by the Tukey test. Data graphing was presented by utilizing Origin 2021b  and the results were presented as mean ± SEM. 2O. Other acquisition parameters were as follows: P1, 12 μs; time domain, 65 K; and eight scans.The 1D and 2D NMR (COSY) spectra of all the samples were recorded at 298 K using a Bruker Advance III 400 spectrophotometer. The resonance frequency was 400.13 MHz, and the spectral width was 9.9 ppm. The relaxation delay time, D1, was set as 1.0 s. All samples were incubated at 25°C for 36 h. NMR measurements were made by reacting 0.2 mM Cys, 0.2 mM CSSC, 1.0 mM Hcy, and 0.5 mM HSSH with 10–20 equivalents of CB[7] in 5 mM sodium phosphate (pH 6.0) and 5 mM carbonate-bicarbonate buffer (pH10.0) in D−1. Cys, CSSC, Hcy, and HSSH powders were used as controls. The Raman spectra were acquired using powders obtained by incubating 50 mM Cys and Hcy at pH 6.0 and 10.0, respectively, for 36 h and then drying the samples using a centrifugal vacuum concentrator .Raman spectra were recorded using 785 nm radiation from a diode laser over the range of 100–3,200 cmThe chemical complexation of Hcy with CB7] was examined using a DTNB assay. DTNB reacts with a thiol group (-SH) and exhibits an absorbance maximum at 412 nm. The DTNB assay involves a reversible reaction that is suitable for host–guest binding studies  was investigated using γ and 1.55–1.75 for Hβ) displayed a substantial upfield shift compared with those of Hcy alone (δ in ppm = 2.55–2.75 for Hγ and 2.00–2.20 for Hβ) (α) was also shifted to a higher field (Δδ = −0.37 ppm), indicating that the guest molecule, Hcy, was included in the cavity of the host, CB[7]  . Thus, iα), 2.74 (Hγ), and 2.04 (Hβ)  of 3.51 (H.04 (Hβ) . These s.04 (Hβ) . These r.04 (Hβ)  and Rama.04 (Hβ) . The 2D .04 (Hβ)  and HSSH.04 (Hβ)  also exhIn the presence of CB[7], the resonances for the β’ and γ’ protons of HSSH were shifted upfield  and 2H uMeanwhile, 2D NMR data suggested that Cys-CB[7] complexation occurred at pH 6.0, but not at pH 10.0. The CSSC-CB[7] complexation was not detected at pH 6.0 or 10.0 (data not shown). According to the 2D NMR results, Hcy oxidizes to HSSH under basic conditions and efficiently forms a supramolecular complex with CB[7].Investigations by 2D NMR spectroscopy revealed that Hcy was oxidized to HSSH, resulting in efficient supramolecular complexation with CB[7] under basic pH conditions. Therefore, we used the DTNB method to study the time-dependent autoxidation of Cys and Hcy under acidic and basic pH in aqueous solutions in the absence of CB[7]. After 36 h of incubation, the absorbances of Cys (pH 6.0), Cys (pH 8.8), and Hcy (pH 6.0) solutions mixed subsequently with DTNB decreased by up to 32.14, 17.82, and 18.20% -3C. MeanFigs. 1D−1) (−1) in the Raman spectrum  . After 3spectrum . Moreovespectrum  and 4C. This is the first report on the selective complexation of HSSH over Hcy with CB[7] under basic pH conditions (pH 8.8~10.0). We explored the supramolecular complexation of the CB[7] host with two biothiol guests, Cys and Hcy, in buffer solutions of different pH. Based on the results of the DTNB assay and 2D NMR investigations, we propose a supramolecular model for the complexation of Cys and Hcy with CB[7] depending on the pH condition . AccordiFigs. 1AFigs. 1BFigs. 1DFigs. 1C3+) (pKa = 9.44) of HSSH stabilizes the complex through attractive interaction with the carbonyl portal of CB[7], and the carboxylate group of HSSH is located outside the CB[7] cavity owing to electrostatic repulsion between the anionic carboxylate group and the carbonyl oxygen atoms of the CB[7] (n] cavity (9.1 Å), complexes of protonated diamines with five or six methylene groups were reported to have the highest stability (KCB[6] = 2–3 × 108 M−1)  cavity, critically contributes to the formation of a stable HSSH-CB[7] complex.The turnover rate of the oxidation of Hcy to HSSH in the presence of CB[7] under basic conditions was 150 times faster than that in the absence of CB[7]  and 3D. 26he CB[7] . Given t108 M−1) . Therefoa and lacks a methylene unit compared to Hcy, could hardly be included in the cavity of CB[7]. As the total concentration of Hcy in the plasma or serum is approximately 5 to 10 μM, host–guest complexation with CB[7] will be useful in detecting the cardiovascular risk factor, Hcy concentration, in plasma or serum samples.On the other hand, Cys, which has a low pK


HOMO and LUMO energies, as well as the electrical characteristics, have been calculated using DFT/B3LYP calculations with Gaussian 09 program. The optimized lowest energy configurations of the complexes are proven. The disc diffusion technique was used to test the pharmacological activities' antibacterial efficacy against diverse bacterial and fungus species. The MTT technique was used to assess the in vitro cytotoxicity of the ligands and their metal complexes on the Hep-G2 human liver carcinoma cell line and the MCF-7 human breast cancer cell line. All compounds displayed better activity compared to the free ligands. MnL2 complex showed predominant activity when compared to the other complexes with an IC50 value of 2.6 ± 0.11 μg/ml against Hep-G2, and against MCF-7 the IC50 value was 3.0 ± 0.2 μg/ml which is less than the standard drug cisplatin (4.0 μg/ml). UV–vis electronic spectrum and gel electrophoresis techniques have been used to investigate the compounds’ affinity to bind and cleavage CT-DNA. The interaction’s binding constants, or Kb, have been identified, and it was discovered that the new complexes' binding affinities are in the order of FeL1 > MnL2 > CrL2 > CrL1, and the binding mechanism has been suggested. To assess the kind of binding and binding affinity of the investigated drugs with human DNA, a molecular docking study was carried out (PDB:1bna). The acquired results supported the intercalation binding mechanism proposed in the experimental part and revealed that complexes may be inserted into the DNA molecule to stop DNA replication. According to ADMET data, the synthesized compounds have a high bioavailability profile and their physicochemical and pharmacological features remained within Lipinski's RO5 predicted limitations.In this study, four new Mn(II), Fe(III), and Cr(III) complexes with two Schiff base ligands namely, 4-bromo-2-[(E)-{[4-(2-hydroxyethyl)phenyl]imino}methyl]phenol (HL1) and 2-[(E)-{[4-(2-hydroxyethyl)phenyl]imino}methyl]-4-methoxy phenol (HL2) have been synthesized and characterized. Different analytical and spectral methods have been used to characterize the ligands and their complexes. General formulas of [M(L)Cl The salicylaldimine complexes are utilized as models for many theoretical interests and structural, magnetic, spectroscopic, catalytic, and redox characteristics12. There have been reports of the pharmacological properties of Schiff base complexes with NO donor atoms, including biological activity against bacteria, fungi, and specific types of malignancies14. Stable complexes of the NO bidentate Schiff base ligands containing the methoxy group formed through coordination with transition metal ions. The resulting complexes have a variety of uses, including catalysis, electrocatalysis, biochemistry, and spectroscopy16. It has shown that the imine group present in the bidentate ligands plays a critical role in their biological activities20. The coordination chemistry of transition metal complexes containing ligands of the salicylaldimine family that have been substituted is of considerable and rising interest. Non-platinum transition metal complexes have received great attention recently because they may be able to reduce the severe side effects and high cost of care associated with platinum-based medication prospects.In recent years, many researchers have focused on Schiff bases and related complexes as a significant class of therapeutic molecules with a vast potential for biological efficacies like antibacterial, anticancer, anticonvulsant, and antioxidant properties22. A substantial number of Schiff base manganese (II), iron (III), and chromium complexes are successful models of biological systems and have a potential biological interest23, such as supramolecular and helical assemblies24.The manganese(II), iron(III), and chromium(III) Schiff base complexes of azomethine donors exhibit an important function in nucleic acid chemistry because of their structural stability and adaptability to biological proteins30 and35, we offer here facile approaches for the synthesis and characterization of two novel bidentate Schiff base ligands (HL1 and HL2), (4-bromo-2-[(E)-{[4-(2-hydroxyethyl)phenyl]imino}methyl]phenol (HL1) and 2-[(E)-{[4-(2-hydroxyethyl)phenyl]imino}methyl]-4-methoxy phenol (HL2)) and their metal complexes CrL1, FeL1, CrL2 and MnL2. Various spectroscopic, structural, and analytical techniques combined with theoretical DFT calculations have been employed to deduce the composition, structure, and geometry of the prepared complexes. The pharmacological activities’ antibacterial efficacy against diverse bacterial and fungus species. The MTT technique was used to assess the in vitro cytotoxicity of the ligands and their metal complexes on the Hep-G2 human liver carcinoma cell line and the MCF-7 human breast cancer cell line. Additionally, as CT-DNA is considered a primary target molecule for the majority of anti-cancer and antiviral medicines, the binding manner of the metal azomethine chelates with CT-DNA will be suggested. Moreover, to assess the kind of binding and binding affinity of the investigated drugs with human DNA, a molecular docking study was carried out (PDB:1bna). The pharmacokinetic and biological actions of the two Schiff bases and their complexes were predicted using Swiss ADME, PASS and pkCSM online software.One of the major health crises of today’s world is antimicrobial drug resistance and there is a great need to discover new compounds that may be effective against antibiotic-resistant bacteria, given the increased occurrence of serious opportunistic bacterial infections in immunologically deficient patients, along with the growth of resistance among pathogenic gram-negative and gram-positive bacteria. Motivated by the promising structural and biological properties of Schiff based metal complexes together with our perpetual engagement in this kind of research endeavors3.6H2O, FeCl3.6H2O and MnCl2.4H2O were of analytical quality and were acquired from Sigma Aldrich.All of the substances utilized, including 2-(4-aminophenyl)ethan-1-ol amine, 5-bromosalicylaldehyde, 5-methoxysalicylaldehyde, CrCl.Supplementary file Section  comprise2. HL1 had a yield percentage of 78%, whereas HL2 had a yield rate of 79%. (Scheme Condensation of 2-(4-aminophenyl)ethan-1-ol , which was dissolved in ethyl alcohol, was used to prepare the ligands (20 ml). The product solution was diluted by 20 ml, and either 1 mmol of 5-methoxy salicylaldehyde (0.30 gm) or 1 mmol of 5-bromo salicylaldehyde (0.20 gm) was to it. The final mixture was refluxed at 79 °C for one hour. Orange precipitate was collected, filtered, and subjected to several ethanol washes. The mixtures were vacuum-dried over anhydrous CaCl3.6H2O, 0.26 g),  or ]. The metal ion solution was dropwise mixed with a 1 mmol solution of the bidentate ligand, and the solution was refluxed for 2 to 6 h at 79 °C while being stirred. The precipitate that resulted from this was gathered using a filter, washed with ethanol, and afterward dried in an oven23. , Fe(III), and bivalent Mn(II), we employed the hybrid exchange–correlation function with the basis set levels of B3LYP/6-31G  for C, N, and O and B3LYP/LANL2DZ for trivalent metals Cr(III), Fe(III), and bivalent Mn(II).We used the Gaussian 09 computer program to conduct a Density Functional Theory (DFT) analysis to ascertain the optimal structures of the ligands HL1, HL2, and their complexes25. In the supplemental file, specifics of the antimicrobial research' methodology are illustrated  NRRLB-543, Pseudomonas vulgaris RCMB 004 (1) ATCC 13315, A. Albicans RCMB005003 (1) ATCC 10231, and A. Fumigatus (RCMB 002008) are among the bacterial species. At different dosages, such as 10, 20, 50, and 100 g/ml, the antibacterial and antifungal activity of the two ligands, as well as their CrL1, FeL1, CrL1, and MnL2 complexes, was assessed Section .4 cells/ml. Each well received 100 ml of the cell solution pipetted into it using a micropipette. For 24 h, 37 °C was maintained on the plate to encourage cell attachment.The MTT  test was performed against the Hep-G2 liver carcinoma cell line and the MCF7 breast cancer cell line to determine the cytotoxicity of the two ligands and their Mn(II), Fe(III), and Cr(III) complexes. Each well of the 96-well plate was seeded with 5000 cells. Using the complete medium, the cell suspension was diluted to a concentration of 5 × 1025. Other details are in the supplementary file  and progressively raising the calf thymus DNA concentration from (10 μM) to (100 μM). The interactions of the new Fe(III), Cr(III), and Mn(II) complexes with calf thymus DNA were calculated using the equation shown below to determine their intrinsic binding constant (Kb)26:The novel compounds’ affinity for interacting with the DNA of the calf thymus was examined using absorption spectra (CT-DNA). Electronic absorption spectra are acquired utilizing a 1.0 cm quartz cuvette at room temperature, keeping the complex concentration at , Fe(III), and Mn(II) complexes interact with CT-DNAWith the use of molecular docking, the stability of different metal Schiff base complexes can be examined, and the optimal binding alignment and shape for molecules interacting in space may be anticipated. The docking experiment was carried out on a Dell Precision TM T3600 workstation adopting the Molecular Operating Environment (MOE) package version 2016.08. We employed the 1.9 resolution X-ray crystal structure of a B-DNA dodecamer d(CGCGAATTCGCG)2 running in the 3'-5' direction for our docking experiment (PDB ID: 1BNA).The MOE software was used to evaluate the DNA structure before hydrogen atoms were added and an energy optimization procedure was carried out.30.The generated model was put by a thorough conformational search using the default position finding tool parameters of the MOE program and an RMS gradient of 0.01 kcal/mol. The Schiff base ligands (HL1 and HL2) and their complexes with trivalent metals (Cr and Fe) and bivalent Mn were included in Chem Bio Draw Ultra 12.0 for further development in MOE. The docking procedures were followed exactly as described in the literature2(H2O)2] for FeL1, CrL1, and CrL2, and [M(L)Cl(H2O)3] for MnL2. A DMSO solution (1 × 10−3 M) is used to evaluate the molar conductance of metal complexes at ambient temperature. The results show that the metal complexes with molar conductance values of 2.68 to 8.12 S cm2 mol−1 are non-electrolytes.The analytical outcomes for the HL1 and HL2 Schiff bases, as well as those of their complexes with Fe(III), Mn(II), and Cr(III), are all displayed in Table 1HNMR spectra of the two ligands . The aromatic protons may be the origin of the multiplets that were seen in the spectra of both ligands, which were in the range of 6.90–7.35 and 6.90–7.35 ppm for ligand HL1 and HL2, respectively. The proton of the azomethine group  is represented by the singlet signal at 8.91 ppm in the spectra of the two ligands, HL1 and HL2  of the side chains of the two ligands may be responsible for the multiplet signals for HL1 and HL2 occurring at 2.76–3.65 ppm and 2.51–3.83 ppm, respectively. The typical signal for the –CH = N group was visible at 161.53 and 163.17 ppm in the 13C NMR spectra for HL1 and HL2, respectively, in Figure The 4H of the ethyl group  was suggested by two signals in the IR spectra of the HL1 and HL2 ligands at (1612 and 1610) cm−132. The complexes’ spectra showed that these signals were shifted to the region between 1625 and 1594 cm−1, demonstrating coordination of the azomethine group with metal ions. The bidentate ligands also displayed a band at 1271 and 1290 cm−1 for the v(C–O) stretching vibration.The redshift of this band to 1265–1247 cm−1 during complex formation is proof that the oxygen atom in phenol was coordinated. Additional evidence for this may be seen in the presence of two bands at 580–536 and 475–452 cm−1, respectively, which are related to the stretching vibrations of the M–O and M–N bonds in the complexes33.The related Cr(III), Mn(II), and Fe(III) complexes, as well as the ligands HL1 and HL2, have FTIR spectra that are shown in Figure At room temperature, DMF was used to record the electronic spectra of the ligands and their complexes with Cr(III), Mn(II), and Fe(III). These results are displayed in Fig. 4A2g(F) → 4T2g(F), 4A2g(F) → 4T1g(F) and 4A2g(F) → 4T1g (P), respectively which implies an octahedral geometry. The magnetic moment value was reported to be between 4.01 and 4.05 B. M., which is in good accord with the values for the Cr(III) complex in octahedral geometry that are already reported34. The transitions 6A1g → 4T1g(4G), 6A1g → 4Eg(4G), 6A1g → 4Eg(4D) and 6A1g → 4T1g(4P), in the solid reflectance spectra of the MnL2 complex at 477, 452, 408, and 288 nm31, respectively, can be due to the octahedral structure surrounding the Mn(II). The octahedral structure is supported by the measured value of 5.22 B. M. for the Mn(II) complex. The transitions are linked to three bands at 570, 409, and 337 nm that are seen in the Fe(III) complex's electronic spectra. Specifically, 6A1g(S) → 4T1g(G), 6A1g(S) → 4T2g(G) and 6A1g(S) → 4Eg,. This compound has an octahedral structure with a high spin number36.In Table 15H14NO2Br and C16H17NO3 are in a favorable range compared to the predicted value. The ESI–MS spectra of the CrL1, FeL1, CrL2 and MnL2 complexes after complexation are depicted in Figure The mass spectra of all compounds displayed a variety of fragmentation patterns as was expected, and the results were found to be in good agreement with the molecular formulae of the compounds. According to the mass spectra of HL1, which displayed a molecular ion peak at m/z = 320.21 and HL2 at 271.93 a. m. u. (320.19 and 271.32 a. m. u.) in Figure The use of TGA is essential for assessing the properties of new metal complexes, distinguishing the different solvent molecules that are present within or outside the coordination sphere, and figuring out the thermal stability of the complexes. In addition to the outcomes of the microanalyses, the results of the TGA, which was carried out between 20 and 800 °C, were utilized to assess and compute mass loss.Table 2O molecules during the first breakdown stage, which took place between 42 and 303 °C + 2HCl, as well as one hydrated water molecule + hydroxyl group in the case of CrL1, and a loss of C2H5O in the FeL1 complex.In the TG curves of the CrL1 and FeL1 complexes, three weight losses events can be seen. Weight losses of 28.96 and 31.98% (estimated at 29.02 and 31.95) are believed to indicate losses of two coordinated H15H12BrN and C13H8BrN moieties, with weight losses from the complexes estimated to be 57.54 and 53.51% , respectively. With weight losses of 13.67 and 14.89%  and DTG curve correlations at  and , respectively, CrO and FeO are the remaining final residues.The second phase took place between 287 °C and 680 °C and involved the losses of the CThe initial degradation phase occurred between 89 and 299 °C and was followed by weight losses of 8.35 and 4.23% , which for the CrL2 and MnL2 complexes, respectively, amounted to the loss of two coordinated and one hydrated water molecule.15H13ONCl2, three coordinated water molecules, and HCl moieties and occurred between 146 °C and 398 °C. In the third stage, which occurred between 22 °C and 587 °C, the complexes lost CH3O and C16H15NO2, with estimated weight losses of 7.17 and 58.51% , respectively. As the final residues, CrO and MnO had weight losses of 15.78 and 16.34% , which are in agreement with the DTG curves at  and , respectively.The TG curves for the CrL2 and MnL2 complexes show four weight loss events. The second process involved the loss of the CDue to difficulties in obtaining single crystals of the produced metal complexes, Fig. 3.The lattice constants of the HL2 ligand’s unit cell, which changed into noteworthy, are as follows: a = 8.322, b = 6.8010, c = 12.8850, = 91.74°, and unit cell volume V = 728.93 Å3. These cellular parameters performed the situation wherein a = b = c and α = β = γ = 90° as required for the pattern to be cubic.At least 10 distinct, highly intense diffraction peaks were visible in the ligand HL2’s diffractogram at 2θ = 13.74°, 14.32°, 15.22°, 18.62°, 21.23°, 23.52°, 26.48°, 27.75°, 28.40°, 30.13° with maxima at 2θ = 13.74°, which corresponds to an inter-planar spacing (d) value of 6.44 Å. As for the CrL2, the acquired unit mobile yielded values of lattice constants, a = 12.3488 Å and unit cell volume of V = 1883.10 Å33. Where t = 0.9 /B cos θ, t = 0.9 /B cos, where t is the crystal thickness (in nm), B is the half-width (in radians), is the Bragg angle, and is the wavelength, is the formula for calculating the particle size. The particle size corresponding to each diffraction maximum is calculated from the half-width of the diffraction peak. CrL2 complex crystals measure 60.27 nm on average.Thus, it can be concluded that Cr(III) complex has only one purely crystalline phase having a monoclinic crystal system. More than fifteen strong diffraction peaks may be found in the XRD pattern of the CrL2; the feature ones are regarded as 2θ = 12.05°, 20.32°, 23.88°, 24.96°, 28.90°, 31.56°, 32.40°, 37.83°, 41.33°, 43.96°, 46.47, 52.91 with maxima at 2θ = 22.38° corresponding to d value of 3.969 Å. The average particle size (dXRD) in Table As single crystals of the ligand and complexes could not be received notwithstanding the first-rate efforts, molecular modeling has been employed to higher understand the geometrical structures of the compounds presently studied.1, O2, and N1 are the more detrimental active sites for L1, whereas O1, O2, O3, and N1 are the more detrimental active sites for HL2. These natural charges were discovered via Natural Bond Orbital Analysis (− 0.506). (NBO).Figure 2 and N1 creating a stable 6-membered ring for both, the metal ions choose the bidentate coordination.So, rather of O2O)2Cl2] optimized ]'s structure in its lowest energy configuration.Figure 1, O2, O4, and O3 virtually on a single plane with a 0.402° deviation  to 2.789 (in the complex [[Fe(L1)(H2O)2Cl2]). The coordinated atoms in [Fe(L1)(H2O)2Cl2]) have the following natural charges calculated from the NBO analysis: Fe (+ 0.405), O2(− 0.579), N1(− 0.433), O3(− 0.870), O4(− 0.870), Cl1(− 0.387), and Cl2 (− 0.391).The six-coordinated octahedral structure of the iron atom has the elements Non Table . As a re2O)2Cl2] and [Cr(L2)(H2O)2Cl2] in their optimized structures. The chromium atom is organized in an octahedron with six coordinated bonds, and in the complexes [Cr(L1)(H2O)2Cl2] and [Cr(L2)(H2O)2Cl2], the atoms N1, O2, O4, and O3 are almost parallel to one another with deviations of 0.287° and 0.571°, respectively.Figures 1 and O2 is decreased from 4.107 Å and 4.109 Å (in free L1 and L2) to 2.787 Å and 2.764 Å (in the complexes [Cr(L1)(H2O)2Cl2] and [Cr(L2)(H2O)2Cl2], respectively) due to coordination of both N1 and O2. The natural charges computed from the NBO analysis on the coordinated atoms in [Cr(L1)(H2O)2Cl2] are Cr (+ 0.402), O2(− 0.554), N1(− 0.443), O3(− 0.882), O4(− 0.879), Cl1(− 0.368) and Cl2(− 0.387). The natural charges computed from the NBO analysis on the coordinated atoms in [Cr(L2)(H2O)2Cl2] are: Cr (+ 0.385), O2(− 0539), N1(− 0.436), O3(-0.880), O4(− 0.877), Cl1(− 0.382) and Cl2(− 0.399).Table 2O)3Cl] complex.Figure 1, O2, O4, and O3 atoms of the complex are almost in the same plane but are displaced by 10.60 degrees suggesting an octahedral geometry of the complex.The coordination number of the Mn atom is six and the N1 and O2, the distance between N1 and O2 is reduced from 4.107 and 4.109 (in free L2) to 2.838 (in the complex [Mn(L2(H2O)3Cl]) Table Due to the coordination of both N2O)3Cl] have natural charges of Mn (+ 0.581), O2(− 0.745), N1(− 0.490), O3(− 0.904), O4(− 0.921), O5(− 0.904), and Cl1 (− 0.564).The coordinated atoms in , [Cr(L2)(H2O)2Cl2], [Fe(L1)(H2O)2Cl2] and [Mn(L2)(H2O)3Cl] complexes; respectively, Table 2O)2Cl2]˃[Mn(L2)(H2O)3Cl]˃[Cr(L2)(H2O)2Cl2]˃[Cr(L1)(H2O)2Cl2] > L1 > L2.The binding free energies of HL1, HL2, and their metal complexes with the protein receptor (PDB:1bna) are determined to be − 2.3, − 2.2, − 27.0, − 27.7, − 32.6, and − 29.9 kcal/mol in the current study for HL1, HL2, [Cr(L1) prediction is used to predict the toxicity and pharmacological properties of studied compounds using the Swiss ADME server, Tables 47. Because of their computed log p values of 3.26, 1.54, and 1.54 for HL1, CrL1, and FeL1 respectively, the ligand HL1 and its CrL1 and FeL1 complexes may permeate biological membranes. According to SWISS ADME software, the CrL2 and MnL2 of the HL2 ligand have respective values of 2.66, 0.93, and 0.04 (less than 5) respectively. Total polar surface area (TPSA) values for the ligands HL1, CrL1, and FeL1 are 52.82, 51.16, and 51.16 2 respectively (below 140 2). The hydrogen bond acceptors are 3, 3, 4 while the hydrogen bond donors for HL1, CrL1, and FeL1 are 2, 4, 3. 48. Additionally, the hydrogen bond donors are 2, 3, and 4, while the acceptors are 4, 5, and 6 for the ligand HL2 and its complexes CrL2 and MnL2. The ligand HL2 and its complexes CrL2, and MnL2 have 62.05, 60.39, and 69.62 2 Å2 each (below 140 Å2), respectively. These data imply the efficient transport of it by oral method and inside the GIT  and BBB (Blood Brain Barrier). The bioavailability score is 0.55 (> than 0) which also reveals that the Schiff bases and their complexes are biologically active. Similarly, the ADMET property analysis reveals that it has a 95.64% ability to undergo absorption inside the human GIT. The log Kp value of the compounds.Most lead-like compounds fail in clinical trials due to weak pharmacokinetic ADMET properties. Before lead-like compounds enter the preclinical phases, in silico testing aids in drug design development, saving time and resources. Using SWISS ADME online software, the pharmacokinetic behavior of the Schiff base ligands and their complexes was investigated. Using Lipinski’s rule of five, the software's output may be assessed, and the results are shown in Tables 13HL1, CrL1, and FeL1 are − 6.03, − 6.64, and − 6.66 cm/s and − 6.24, − 6.85, and − 7.67 cm/s for compounds HL2, CrL2, and MnL2 respectively (which is less than 2.5). The results show that the ligands and their complexes are distributed more in blood plasma and less in tissue and therefore no renal failure and dehydration is caused. It is metabolized by CYP1A2 inhibitor, CYP2C19 inhibitor, CYP2C9 inhibitor, CYP2D6 inhibitor, and CYP3A4 inhibitor enzymes. These enzymes render the oxidation process and facilitate their excretion. It has nontoxic value and non–carcinogen in nature.50. Thus, there is an urgent need to derive the Structure–Activity Relationship (SAR) model to correlate the practical activity of the subject compounds (herein IC50) with their calculated chemical descriptors and find the most effective description model52. SAR model was constructed by correlating the practical activity (IC50) of the subject compounds with their theoretical chemical descriptors , Eq. , Eq. 53,54.4\d50), Eqs. , Eqs. , 7, 8;5\1 and its complexes against both of MCF-7 and HepG2. While, practical activity depends on both of Ionization potential (IP) and electrophilicity index (ω) in the case of L2 and its complexes against both of MCF-7 and HepG2. To investigation the validity of derived formula, IC50 values were calculated using Eqs. , it is obvious that practical activity depends on both of electrophilicity index (ω) and dipole moment (µ) in the case of L, it is oing Eqs. , 7, 8 an50 of 4.0 µM and 4.8 µM against the Hep-G2 and MCF-7 cell lines respectively. MnL2 complex has superior anticancer efficacy compared to the other complexes. Molecular docking study confirmed the binding affinity of the complexes with DNA, the obtained results revealed that the binding energy of the free ligands and their complexes with the receptor PDB:1bna follows the order: FeL1 > MnL2 > CrL2 > CrL1 > HL1 > HL2. FeL1 and MnL2 complexes showed superior binding energy values of − 22.0 and − 21.9 kcal/mol. The pharmacokinetic and biological actions of the two Schiff bases and their complexes were predicted using Swiss ADME, PASS and pkCSM online softwares.In conclusion, our work concentrated on four novel complexes of Fe(III), Mn(II), and Cr(III) obtained from two bidentate ligands, each of which had a different substituent in the salicylaldimine molecule. Various spectroscopic and analytical approaches were used to suggest the chemical structures of the novel complexes FeL1, CrL1, CrL2, and MnL2. The non-electrolytic nature of the compounds was concluded based on the molar conductivity results. FT-IR spectral data revealed that the two ligands HL1 and HL2 behave as monobasic bidentate ligands coordinating the Fe(III), Cr(III), Mn(II) metal ions through the phenolic OH and C = N functional groups. UV–vis spectral data and magnetic moment values suggest the octahedral structure of all complexes, the octahedral geometry of the novel compounds has been validated and optimized by DFT analysis. The estimated parameters showed that the free ligands provide electrons to the various metal ions, establishing a stable six-membered chelate ring. All the novel complexes have shown enhanced antibacterial efficacy against a wide spectrum of microorganisms. The in vitro cytotoxicity results showed that the new compounds were significantly more hazardous to cancer cells than the widely used drug cisplatin, which has an ICSupplementary Information 1.Supplementary Information 2.Supplementary Information 3.


Rhizoctonia solani. All the synthesized compounds showed excellent antifungal activity in their minimum concentrations (10–0.62 μM). Among all the synthetics, compounds 5b (ED50: 2.33 μM), 5f (ED50: 0.96 μM), and 7f (ED50: 1.48 μM) exerted a superior inhibitory effect in comparison to the commercially available fungicide, hexaconazole (ED50: 2.44 μM). The binding interactions of the active compounds 5f, 7f, 6, and 8 within the active site of the sterol 14α-demethylase enzyme were studied with the help of molecular docking studies. The studies revealed that these hybrid pharmacophores could be used as an important intermediate to demonstrate new structural isomer-based fungicides.In order to explore new antifungal agrochemicals, we reported the synthesis of two series 5a–f, 6 and 7a–f, 8 of benzothiazole-appended bis-triazole derivative-based structural isomers using a molecular hybridization approach. The synthesized compounds were tested for fungal growth inhibition against the plant pathogen  Rhizoctonia solani. It was found that compound 5f is the most potent fungicide.Two novel series  of benzothiazole-appended bis-triazole derivative-based fungicides were prepared and their antifungal activity evaluated against plant pathogen  According to the statistics of the World Harvest of Food and Agriculture Organization of the UN (2009–2010), pathogenic fungi, particularly Rhizoctonia solani Kuhn fungus, globally affect five major crops, namely rice, wheat, maize, potatoes, and soybean.4 This fungus gives rise to sheath blight disease  and leaf blight in rice that causes stunting, wilting of plant leaves, and possibly plant death.5 It is well documented that the permeability, fluidity, and viability of the fungal cells are maintained mainly by sterols. Predominantly, ergosterol  found in most of the fungal cell membranes has become an emerging target of the majority of clinically used therapeutics.6The agricultural industry is scrambling at a great pace to meet the requirements of food for the exponentially growing world population. One of the major hurdles in fulfilling global food security is debilitating plant diseases.7 Several other drugs under various stages of clinical trials also give an effective therapeutic choice to treat fungus-generated diseases. The increased chemical burden for controlling fungal diseases to improve the yield of crops has led to multiple drug resistance, crop toxicity, soil infertility, and environmental pollution.8,9 Therefore, the development of a new environment-friendly class of drugs possessing more bioactive sites is needed to be more effective against plant fungal infections with lower health risks.10 Herein, the concept of molecular hybridization plays a vital role in developing a coherent design of novel multitarget hybrid antifungal agents. Combined scaffolds probably propose some leads in minimizing drug resistance and enhancing their biological potency.To override the problem of crop loss caused due to fungal diseases, several fungicides are available in the global market that target the fungal cell membrane to disrupt its cell wall.11–15 Apart from the antifungal activity, these heterocyclic scaffolds are also reported as privileged fragments due to their high affinity toward various biological targets in modern medicinal chemistry.16–19Exploration of novel and potent antifungal agrochemicals can be achieved by the optimization and modification of the existing agents by minimizing their side effects. Many reports of available fungicides  containi20 This inhibition of ergosterol biosynthesis leads to the suppression of fungal growth.21 Based on these findings, some novel hybrid pharmacophores containing triazole, pyrrole, benzothiazole, sugar, and isatin motifs have been formatted within a single molecule to obtain globally demanded antifungal agents  studies have been utilized to get a clear idea concerning the mechanism of action of the drugs.2.2.1.2CO3 in acetonitrile at 70 °C to afford two isomers, 1 and 2, in 1 : 1 yield, as shown in The methodology for the formation of benzothiazole-appended bis-triazole derivatives involved two steps. In the first step, 2-aminobenzothiazole was allowed to react with propargyl bromide in the presence of Kvia the click chemistry approach as depicted in d-glucose (4) were prepared by the experimental conditions reported in the literature.23 These compounds were further treated with alkynes 1 and 2 in the presence of copper sulphate and sodium ascorbate in the different solvent systems at 80 °C to afford the corresponding desired derivatives. Furthermore, 5e and 7e were refluxed with l-hydroxyproline in ethanol in the presence of InCl3 for 3 h to get the corresponding derivatives 5f and 7f, as shown in In the second step, the benzothiazole-appended bis-triazole derivatives 5a–e, 6 and 7a–e, 8 were synthesized 1H NMR spectrum of the compound 5a, a singlet was observed at δ 4.3 ppm for 4 protons corresponding to the methylene group attached to the nitrogen(s) of the amino benzothiazole ring. Two triplets at δ 4.5 ppm and δ 4.6 ppm for 4 protons were assigned to the methylene group linked with the isatin ring. The characteristic peak appeared as a singlet at δ 8.33 ppm for two protons for the triazole hydrogen. The 13C NMR spectrum of compound 5a showed a peak at δ 180 ppm, which was assigned to the C PBM data was replaced with SVG by xgml2pxml:<glyph-data id="z.dbd" format="PBM" resolution="300" x-size="8" y-size="10" xml:space="preserve">00000000000000000000000000000000111111110000000011111111000000000000000000000000</glyph-data><svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="13.200000pt" height="16.000000pt" viewBox="0 0 13.200000 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 440 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z M0 280 l0 -40 320 0 320 0 0 40 0 40 -320 0 -320 0 0 -40z"/></g></svg>O (keto) carbon of the isatin ring.The structures of all of the synthetics 5a–f, 6 and 7a–f, 8  and 3 weδ 168 ppm was assigned to the imine carbon present in the benzothiazole ring. The peaks that appeared at δ 44.2 ppm and δ 47.3 ppm were assigned to methylene carbons. For compound 7a, the two singlets observed at δ 4.1 and δ 4.2 ppm for 4 protons corresponded to the methylene groups attached to both nitrogens present in the amino benzothiazole ring. Mass spectrometry data for both isomers 5a and 7a showed the calculated mass (M + H) ion of 659.1, satisfying the observed mass of 659.1. The structures of all of the synthesized compounds are shown in The peak appearing at 2.2.2.2.1Rhizoctonia solani. ED50 values were used as the effective concentration measurement required to inhibit 50% growth of the fungus and determined by at least four separate tests. The obtained results revealed that all compounds displayed excellent antifungal activity against Rhizoctonia solani at five concentrations   .The structure–activity relationship (SAR) studies suggested that compounds 5f, 7b, and 7f exhibited excellent inhibitory effects on fungal growth compared to the commercially available fungicide hexaconazole . However2.3.3GW9) molecular docking studies have been performed with minor modifications by using AutoDock Vina.24,25 Deep analysis of the 2D and 3D poses of compounds 5f, 6, 7f, and 8 were performed in a similar manner to that of hexaconazole, the reference drug ,  compared to 7f  indicated more favorable binding interactions with the CYP51 enzyme, which could explain the reason for the superiority of compound 5f over 7f. These docking results substantially agree with the above biological assay data and unveil the appropriate 14α-demethylase inhibitor design.From 3.Rhizoctonia solani. Moreover, the compounds 5f, 7f, and 5b inhibited the fungal growth better than the standard drug hexaconazole. Compound 5f was found to be approximately three times more effective than hexaconazole. Most of the compounds of the 5a–f series exhibited a higher antifungal inhibitory index than their corresponding isomers of the 7a–f series. Also, the replacement of the carbonyl group of the isatin ring with pyrrole was the paramount combination for promising antifungal activity to be focused on for medical applications in the era of fungal diseases. Moreover, molecular docking studies strengthened the results of the biological evaluation that predicted compound 5f as the most active with the highest binding energy . Thus, the overall studies concluded that benzothiazole-appended bis-triazole derivatives could act as potent inhibitors of 14α-demethylase. Therefore, these compounds could be used as an alternative to the commercially available drug hexaconazole for the control of fungal growth in various plants.Two novel series  of benzothiazole-appended bis-triazole derivative-based fungicides that are structural isomers of each other were synthesized using click chemistry and were evaluated for their antifungal activity. The synthetic procedure reported here is reliable, simple, and highly reproducible. All the synthesized compounds showed excellent growth inhibition against The authors do not have any conflict of interest.RA-012-D2RA04465J-s001


SubPN) and fine particles (2.5PM). During cigarette smoking and incense stick-burning scenarios, the particle number concentrations exceeded 3 × 105 cm−3. They exceeded 5 × 105 cm−3 during shisha smoking. The emission rates were 1.9 × 1010, 6.8 × 1010, and 1.7 × 1010 particles/s, respectively, for incense, cigarettes, and shisha. That corresponded to about 7, 80, and 120 µg/s, respectively. Males received higher dose rates than females, with about 75% and 55% in the pulmonary/alveolar during walking and standing, respectively. The total dose rates were in the order of 1012–1013 #/h (103–104 µg/h), respectively, for SubPN and 2.5PM. The above reported concentrations, emissions rates, and dose rates are considered seriously high, recalling the fact that aerosols emitted during such scenarios consist of a vast range of toxicant compounds.Tobacco smoking and incense burning are commonly used in Jordanian microenvironments. While smoking in Jordan is prohibited inside closed spaces, incense burning remains uncontrolled. In this study, particle size distributions (diameter 0.01–25 µm) were measured and inhaled deposited dose rates were calculated during typical smoking and incense stick-burning scenarios inside a closed room, and the exposure was summarized in terms of number and mass concentrations of submicron ( Incense-burning and aroma products are not widely prohibited worldwide, as some countries still use them extensively ,5,6,7,8.Smoking is not only considered harmful for the smoker themselves, but also harmful for the persons nearby, as passive smokers are exposed to the smoke itself being released and transported in the atmosphere, which is known as being a second-hand smoker ,65,66,67Although the Jordanian Ministry of Health has stated that smoking is forbidden in microenvironments , people are still violating this law. In fact, Jordan acquires the highest rate of smoking; 8 out of 10 men consume nicotine products such as cigarettes, shisha , and e-cigarettes. According to previous statistics , about 22, NOx, SO2, PAHs, VOCs , formaldehyde (HCHO), BTEX, and heavy metals [Tobacco smoke consists of up of 4000 chemicals, including (varying greatly between the type of smoking) volatile organic compounds , Acetone, Pyrrole, Pyrroline, Pyrrolidine, Phenolics, etc.), polycyclic aromatic hydrocarbons anthracene, Chrysene, benzo(b)-fluoranthene, benzo(k)-fluoranthene, Benzo(a)pyrene, Indenopyrene, Dibenzoanthracene, Benzoperylene), CO, and heavy metals; these are those ones that have been identified as risk factors for health ,100,101.y metals ,113,114.y metals ,131,132.Here, we aim to present the exposure levels and regional inhaled deposited rate in respiratory tracts during the most common combustion activities in Jordanian microenvironments. The investigation included measurements of particle number size distributions (diameter 0.01–25 µm) during typical smoking and incense stick-burning scenarios inside a closed room. The exposure and dose rates were presented in terms of two metrics (number and mass) of submicron and fine particles. In order to put an insight into the exposure scenarios, the regional inhaled deposited dose rates were calculated for an adult male or female during two of the main human activities .The measurement setup was according to the description provided by Hussein et al. . The set5 cm−3 and 5 × 105 cm−3, respectively. These instruments were operated at 1 s time resolution. Using the AeroTrak extended measured particle diameters to reach 25 µm and allowed for 6 particle size channels: 0.3, 0.5, 1, 2.5, 10, and 25 µm . The AeroTrak sampling time resolution was 30 s at a flow rate of 2.83 lpm.The CPC and P-Trak measure submicron particle number concentrations with cutoff sizes of 10 nm and 25 nm, respectively. The sampling flow rate in these two instruments was 0.1 lpm (inlet flow rate 0.7 lpm). The maximum measurable concentrations were ~103), which was fully furnished and had its window and door closed. Each scenario was repeated four times. The room was naturally ventilated.The exposure scenarios included smoking (cigarette and shisha) and incense stick burning. The scenarios were performed inside an office room (5 × 2.7 × 2.7 mThe cigarette smoking was made by burning two cigarettes within a short time (<3 min). Two shishas were smoked at the same time for a period between 30 min and 90 min. The incense stick scenario included burning two sticks (~20 cm long) at the same time for five minutes.After finishing the smoking and the incense stick burning, the room was kept closed and unoccupied until the particle number concentration reached a level close to what was before the scenario was started. This took a period of longer than three hours.The measured particle number size distribution (eight channels within 0.01–25 µm) was generated by processing the data by the three instruments listed in the previous section ,133. BasThe harmonized aerosol database was processed for 1 min average. The particle number size distribution  was generated by calculating the concentration differences between different instruments: 10–25 nm (CPC and P-Trak difference), 25–300 nm (P-Trak and Aerotrak difference), and 6 channels in the AeroTrak .pρ = 1000 kg/m3).The size-fractionated number and mass concentrations were calculated over the specified particle size range:The size-specific emission rate and losses of aerosol particles were calculated by utilizing a simple indoor aerosol model ,135,136.t is the time; I and O are the indoor and outdoor concentrations of the aerosol particles, respectively; P is the penetration factor of aerosol particles while being transported from the outdoor air into the indoor air; λ is the ventilation rate; dλ is the dry deposition rate of aerosol particles onto available indoor surfaces; and inS represents the emission rates from an indoor source. The subscript i represents a certain particle size range. A well-mixed indoor air domain was ensured because the room size was small enough and a fan was used to produce air convection.While in general, indoor aerosol origin is a combination of indoor or outdoor sources, the indoor aerosol sources in this study are dominated by those sources that are due to smoking and incense burning. The indoor aerosols are eventually lost from the atmosphere by either dry deposition or removal via air exchange. Complex dynamic processes  were ignored. Accordingly, indoor aerosols concentrations can be described by the mass balance equation:In Equation (3), the second and third terms on the right-hand side are the particle losses  and emission rate from an indoor source, respectively. Right after an indoor source is terminated, Equation (3) can be rewritten to calculate the particle losses asPλO << (λ + dλ)I). In Equation (5), the source term is assumed to be dominant I) but it needs to be corrected for the particle losses.Here, Equation (4) is built on the fact that indoor aerosols of indoor origin are dominant . Here, we followed our previous approach described elsewhere [DF(pD)) in the respiratory tracts during exercise or rest , which is the volume of breathed air per time :The measured particle number size distribution  are presented in −1 for particles smaller than 0.1 µm. Those for micron particles were 0.45–5.5 h−1. According to the losses of particles within the range 0.1–1 µm, the ventilation rate (λ) can be around 0.5 h−1. This value agrees with typical values of natural ventilation.Selected particle number size distributions during one case of each exposure scenario are presented in 3 and friction velocity u* = 10 cm/s. This underestimation is expected because the Lai and Nazaroff calculation [roughF) can be smaller than 0.8.The three-layer deposition model calculation, as described by Lai and Nazaroff , shows uculation  is for sculation ; the sur3) was characterized by a skewed unimodal particle number size distribution to small diameters and varying peak values of 75–170 nm (mean 130 nm) and total particle losses of 1.% 2.32 h−1 (mean 2.4 h−1) [−1 [3), the geometric mean diameter of the incense smoke particles was nearly unimodal, with a geometric mean of 80–15 nm [2.5 of incense smoke inside a church showed a loss rate in the range of 1.1 × 10−2–5.5 × 10−2 min−1 (mean 3.2 × 10−2 min−1) [The incense smoke  . In the h−1) [−1 . In anot80–15 nm . The PM25 cm−3 (corresponding to >110 µg/m3) . The total particle number concentrations were higher than 3 × 100 µg/m3) a. The du3) [4 cm−3 during incense burning. In another study conducted inside a small chamber (1.016 × 0.660 × 1.600 m3), the incense smoke (four incense sticks were burned at each of the four corners of the chamber) showed a highest concentration of 1.1 × 106–2.4 × 106 cm−3 [3 for two types of incense varied within 1.6 × 105–2.9 × 105 cm−3 (mean 2.2 × 105 cm−3) [3) [4–6.1 × 105 cm−3 (mean 2.9 × 105 cm−3). In the European Accredited (EA) Laboratory of Industrial Measurements (LAMI) at the University of Cassino and Southern Lazio, a test of three incense-burning scenarios yielded 4.1 × 106–9.8 × 106 cm−3 (PM2.5 6.3–14.6 mg/m3) [In a previous investigation conducted inside a room (2.53 × 2.50 × 5.15 m3) , the tot106 cm−3 . The tot05 cm−3) . The UFPm−3) [3)  had a ma2.5 concentrations inside a church reached values of 36–123 μg/m3 (mean 56 μg/m3), equivalent to 5 × 103–1.4 × 104 cm−3 (mean 6.3 × 103 cm−3) [2.5 concentration at ten temples was reported to be 660 µg/m3, and at two crematoriums, it was reported to be 1050 µg/m3, as a result of incense burning [As a cultural and religious custom, incense burning is widely used in some countries ,5,6,7,8.5 cm−3. The duration of smoking two cigarettes was less than three minutes, and consequently, the aerosol emission span time was very short. Initially, fine particles of all sizes were affected as a result of opening the office to start the cigarette-smoking scenario. However, it was evident that particles smaller than 0.3 µm were the most affected, because their concentrations immediately increased significantly right after starting the scenario. Interestingly, after 10 min of starting the smoking, when the UFP concentrations started to decrease, the concentrations of the accumulation mode (diameter 0.1–1 µm) started to increase as a result of coagulation of the emitted smoke particles. This was also evident in the evolution of the particle number size distributions shown in During cigarette-smoking scenarios c,d, the 3) were as high as 1.2 × 106 cm−3 [2.5 exposure levels as second-hand smoke (five types of Vogue cigarettes) ranged between 1.3 and 2.2 mg/m3 [3), the PM2.5 exposure levels as second-hand smoke were 0.7–1.5 mg/m3 during the testing of five types of Marlboro cigarette [The UFP concentrations of cigarette smouldering evaluated inside in a stainless-steel test chamber  and characterized by a single lognormal mode with a geometric mean diameter of 180 nm and 220 nm [5–109 cm−3 in the mainstream [Particle concentrations in the mainstream are extremely higher than those inhaled by a passive smoker in typical indoor, outdoor, and occupational environments, as well as vehicles: typically in the range of 10106 cm−3 ,178,179.d 220 nm ,181. In instream .5 cm−3) when compared to the background concentrations , these houses reflected real-life conditions inside relatively large indoor environments (apartments and houses), revealing that the submicron particle number concentrations were as high as 1.5 × 105 cm−3  inside the dwellings with cigarette smoking. Those with shisha smoking experienced even higher concentrations ~4 × 105 cm−3 .The literature about shisha smoke characterization is fairly limited when compared to cigarette smoke or incense burning. However, and as pointed out before, shisha smoke temporal variation in this study was similar to what was previously reported in other studies, and can be explained by puffing intensity and frequency, as well as the addition/changing of charcoal ,149. In g = 2.0) whereas the size distribution of the particles emitted from shisha was bimodal (one peak below 10 nm and another peak at 65 nm). The mean particle number concentration in the aerosol chamber over the entire measurement period was 1.5 × 105 and 1.9 × 105 cm−3 for the cigarette and waterpipe smoke, respectively.As expected and reported previously , cigaret2, 4 h smoking), resulting a median particle number concentration of 2.9 × 105 cm−3 , which was equivalent to a PM2.5 of about 390 µg/m3  [In a similar study, a shisha-smoking session was carried out in a room (floor area 20 m0 µg/m3) .10 particles/s; this is equivalent to about 7 µg/s. As for smoking, the total particles emitted were about 6.8 × 1010 and 1.7 × 1010 particles/s, respectively, for cigarettes and shisha. Although the total number emitted during cigarette smoking was more than that during shisha smoking, the total particle mass emitted during shisha smoking (about 120 µg/s) was more than that during cigarette smoking (about 80 µg/s).The size-specific particle emission rate is shown in 3) used to characterize the physical properties of particles in incense smoke (four incense sticks were burned at each of the four corners of the chamber) the emission rate was 5.1 × 1012–1.42 × 1013 particles/h [14–1.1 × 1015 particles/h (PM2.5 19.4–50.3 mg/h) during three incense-burning scenarios [2.5 emission rate of 7–202 mg/h [3 stainless-steel test chamber was 0.4 × 1011 particles/min [2.5 emission rates were 1.1 × 102–3.9 × 102 particles/cm3min (mean 2.5 × 102 particles/cm3min), equivalent to 1.4–3.9 μg/m3min (mean 56 μg/m3min) [The literature has limited and few studies reporting the emission factors during incense-burning and cigarette-smoking scenarios. To our knowledge, emission factors were not reported before for shisha. Inside a small chamber (1.016 × 0.660 × 1.600 mticles/h . In the cenarios . It was 202 mg/h . The UFPcles/min . The PM2g/m3min) .3 stainless-steel test chamber was 3.4 × 1011 particles/min [6 cm−3 and mean total particle losses of 3.9 h−1. The PM2.5 emission rate of 1.2–2 mg/m3s was derived from the exposure levels as second-hand smoke (five types of Vogue cigarette) [3), the PM2.5 emission rate was 580–1250 mg/m3s while testing five types of Marlboro cigarette [The UFP emission rate of cigarette smouldering carried out in a 1.2 × 1.2 × 1.2 mcles/min , with a garette) . In anotigarette .SubPN, diameter < 1 µm) and particulate matter (2.5PM).In order to put an insight into the exposure scenarios, the regional inhaled deposited dose rates were calculated for an adult male or female  during tEV) is higher, and the deposition fraction (DF) curves are slightly different for males than females. On average, the regional inhaled dose rates during the walking scenario were about 7%, 18%, and 75%, respectively, for the head and throat airways (H), tracheobronchial (TB), and pulmonary/alveolar (Alv) regions. During standing, the corresponding dose rates were 25%, 20%, and 55%, respectively. The differences in the regional dose rates reflect the changes in the DF curves between resting and exercising.In general, and regardless of the type of combustion scenario and concentration metric, the total inhaled dose rate was higher in males than females. This is basically due to the fact that male minute ventilation  and the lowest during cigarette smoking . Considering the total dose rate of fine particles  and the lowest was during cigarette smoking . With respect to 2.5PM, the total dose rate was the highest during shisha smoking, with 5.3 mg/h for males , and the lowest was 0.5 mg/h for both males and females.Similarly, the total dose rate during walking (4 km/h) was the highest during incense burning (13.7 × 10EV) is higher during exercise  than during resting . In addition, the DF curves are slightly different between the two cases. However, the main effect comes from the minute ventilation (EV).It is interesting to mention here that the higher dose rates calculated during walking when compared to standings are attributed to the fact that the minute ventilation . Without performing the calculations, the cumulative dose is considerably high that it can impose serious health risk, especially knowing that the chemical combustion of the smoke consists of high contents of toxic compounds and heavy metals.Tobacco smoking and incense burning are commonly practiced in Jordanian microenvironments. While smoking in Jordan is prohibited inside closed spaces, incense burning remains uncontrolled.In this study, the particle size distributions (diameter 0.01–25 µm) were measured inside a room replicating real-life conditions in a Jordanian dwelling. The measurement was made during typical smoking and incense stick-burning scenarios as examples of common indoor aerosol sources and exposure. The results were summarized in terms of number and mass concentrations of submicron and fine particles. The particle losses and emission rates were calculated by utilizing a simple indoor aerosols model.5 cm−3. During shisha smoking, they exceeded 5 × 105 cm−3. The average emission rates were estimated at 1.9 × 1010, 6.8 × 1010 and 1.7 × 1010 particles/s, respectively, for incense, cigarettes, and shisha. That corresponded to about 7, 80, and 120 µg/s, respectively. Interestingly, the exposure levels were almost similar for incense and cigarette-smoking aerosols, but the emission rate from cigarette smoking was about three times that during incense burning. This was expected, because the smoking occurred for a shorter time than the burning of the incense sticks.During cigarette smoking and incense stick-burning scenarios, the particle number concentrations exceeded 3 × 1012 #/h and 103 µg/h, respectively, for submicron particle number concentration (SubPN) and 2.5PM. During walking (4 km/h), they were in the order of 1013 #/h and 104 µg/h, respectively.In general, and regardless to the type of combustion scenario and concentration metric, males received higher dose rates than females, with average percentiles in the different regions of the respiratory tracts of 7%, 18%, and 75%, respectively, for the head and throat airways (H), tracheobronchial (TB), and pulmonary/alveolar (Alv) regions during walking. During standing, the corresponding dose rates were 25%, 20%, and 55%, respectively. The total dose rates during standing were in the order of 102, NOx, and SO2.The exposure levels, emissions rates, and inhaled deposited dose rates during the studied scenarios of smoking and incense burning are considered seriously high, recalling the fact that aerosols emitted during such scenarios consist of a vast range of polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and heavy metals, in addition to harmful gases such CO, COBy all means, the Jordanian authorities have to take immediate actions to enforce the prohibition of cigarette smoking indoors and develop regulations for incense stick burning.


The metastable Li5GaS4 sample was found to have an antifluorite-type crystal structure with cationic disorder, while the stable phase was found to have a monoclinic crystal structure, similar to that of another solid electrolyte, Li5AlS4. In both the structures, the Ga3+ cations were surrounded by four S2− anions in tetrahedral coordination. The conductivity of the metastable phase was determined to be 2.1 × 10−5 S cm−1 at 25 °C, which is 1000 times greater than that of the monoclinic phase. The high conductivity of the metastable phase was achieved owing to cation disorder in the crystal structure.Understanding the differences in the structures and defects in the stable crystalline phase and metastable phase is important for increasing the ionic conductivities of a solid electrolyte. The metastable phase often has higher conductivity than the stable phase. In this study, metastable lithium thiogallate, Li 5GaS4 electrolyte prepared by a mechanochemical process exhibits the highest conductivity of 2.1 × 10−5 S cm−1 at 25 °C, which is three orders of magnitude higher than that of the heated Li5GaS4 samples with the stable phase.A metastable antifluorite-type Li A number of previous studies have suggested that sulfide-based electrolytes meet these requirements. In particular, the ionic conductivities of sulfide electrolytes reach 103 So far, various sulfides, such as Li2S–P2S5 glass-based electrolytes,4–9 thio-LISICON-type crystals,10–14 Li10GeP2S12-type crystals,1,2,15,16 and argyrodite-type crystals,17–20 have been reported as solid electrolytes. These solid electrolytes have been prepared with a wide range of compositions. For example, the thio-LISICON series have been prepared in the form of Li4GeS4–Li3PS4, Li4GeS4–Li5GaS4, Li3PS4–Li4SiS4,etc.12,14,21 Further, the crystal structures and conductivities at room temperature of Li4GeS4, Li3PS4, and Li4SiS4, which are the terminal compositions in binary systems, have been reported. As the other terminal composition, Li5GaS4 has been reported to have a low conductivity of 5.1 × 10−8 S cm−1 at 100 °C;14 however, its crystal structure has not been reported. The Li5GaS4 crystals are stable at room temperature and can be readily prepared by heating a mixture of the starting materials. On the other hand, glassy and amorphous electrolytes are prepared by melt quenching or a mechanochemical process.4–8 In general, glassy and amorphous electrolytes have higher conductivities than the corresponding crystalline phases, because of their higher free volumes. Such glasses are notable precursors for metastable superionic conductive crystals. For example, when the 70Li2S·30P2S5 glass is heated to 240 °C, the superionic conductive phase of Li7P3S11 precipitates as a metastable phase in the amorphous matrix.6,8,22 In addition, metastable crystalline phases can be prepared directly via mechanochemistry,23,24 and metastable crystalline phases often exhibit higher conductivities than the stable crystalline phases. For instance, Li4SnS4 prepared by heating a mixture of the starting materials has a stable orthorhombic crystal structure,25,26 while the Li4SnS4 sample prepared by the mechanochemical process has the metastable hexagonal crystal structure.24 Further, the metastable hexagonal Li4SnS4 has higher ionic conductivity than the stable orthorhombic Li4SnS4.Moreover, sulfide electrolytes have better deformability for densification than oxide electrolytes.5GaS4, whose crystal structure has not yet been clarified. In particular, the formation of the metastable phase of Li5GaS4 by a mechanochemical process  was investigated. Subsequently, crystalline phases were obtained by heating the milled metastable Li5GaS4 sample at different temperatures. The structures of the different crystalline phases were analyzed by X-ray diffraction (XRD) and Raman spectral analyses, and the conductivities of the stable and metastable phases were also examined.In this study, we focused on the thio-LISICON composition of Li2S  and Ga2S3  powders were used as the starting materials for the mechanochemical synthesis of the Li5GaS4 solid electrolytes. A stoichiometric mixture of 5Li2S·1Ga2S3 (= Li5GaS4) was mechanochemically processed at 510 rpm for 100 h using a planetary ball mill apparatus . In this process, 0.5 g of the mixture of the starting materials was milled in a 45 mL zirconia pot with 250 zirconia balls (diameter: 4 mm). After the mechanochemical process, the Li5GaS4 powder was collected; this sample is hereafter referred to as milled Li5GaS4. The milled powder was subsequently heated at 420 or 600 °C for 2 h in a dry argon atmosphere; the heat-treated Li5GaS4 samples are referred to as HT-420 °C or HT-600 °C, respectively. All the steps in the synthesis were carried out in a dry argon atmosphere.Liθ range of 10–80° at a scan rate of 10° min−1. Rietveld refinement of the XRD patterns was performed using the RIETAN-FP software.27 The diffraction data for the Rietveld refinement were collected in steps of 0.02° in the 2θ range of 10–130° at a scan rate of 1° min−1 using monochromatic Cu-Kα1 radiation. For the Rietveld refinement, first, the peak shape, background coefficient, scale factor, and lattice constants were refined. Then, the occupancy was fixed at the stoichiometric composition, and the isotropic displacement parameters of sulfur and gallium were refined. The crystal models were obtained using the VESTA software.28X-ray diffraction (XRD) of the powder was performed on an X-ray diffractometer  using Cu-Kα radiation. The diffraction patterns were obtained in steps of 0.02° in the 2Raman spectroscopic analysis to identify the local structural units in the solid electrolytes was carried out using a Raman spectrophotometer  equipped with a 532 nm diode-pumped solid-state laser.7 to 10−1 Hz using an impedance analyzer  at an applied AC voltage of 50 mV. The prepared electrolyte powders were pressed at 360 MPa to form pellets at room temperature (∼25 °C). The diameter and thickness of the pellets were approximately 10 mm and 1 mm, respectively. Thin gold films were coated onto the entire surface of the pellets on both the sides to serve as current collectors. The ionic conductivity was measured in the temperature range of approximately 30–75 °C. Activation energies (Ea) were calculated from the slopes of the Arrhenius plots and then the conductivities at 25 °C (σ25°C) was obtained by extrapolation.The ionic conductivity of the solid electrolyte was determined through electrochemical impedance spectroscopy. The impedance data were obtained in the frequency range of 105GaS4 was prepared by a mechanochemical process. Then, the milled sample was heated at 420 or 600 °C to obtain heated samples (HT-420 °C or HT-600 °C). The milled and heat-treated samples were white powders. 5GaS4 samples, along with those of the starting materials. The XRD patterns of the prepared Li5GaS4 samples contain peaks of unknown phases, as indicated by blue circles or red stars  appeared in the XRD pattern. The peaks marked by red stars could be indexed to the monoclinic structure. Upon heating at a higher temperature of 600 °C, only the peaks marked by red stars were observed. Thus, as the heat-treatment temperature was increased, the peaks indexed to the cubic structure disappeared, while the peaks indexed to the monoclinic structure appeared. These results suggest that the cubic structure is the metastable phase, while the monoclinic structure is the stable phase.First, the solid electrolyte, milled Lied stars . The pea5GaS4 and the heated samples. The spectrum of the milled sample shows a broad peak centered at ∼335 cm−1. This peak may contain multiple peaks, but the peak separation is difficult. The peak does not include the component of Ga2S3 used as the starting material, because its main peak appears at a different wavenumber. Upon heating the sample, the Raman spectrum changed; an asymmetric peak appeared at ∼345 cm−1 in the spectrum of HT-420 °C, while two strong peaks appeared at ∼310 and 340 cm−1 for HT-600 °C. Note that the bands at ∼310 and 340 cm−1 have not been attributed to any units in glasses containing Ga2S3 in previous studies.29,30 Based on the X-ray crystal structure results of HT-600 °C, which will be discussed later, the Raman bands at 310 and 340 cm−1 observed for HT-600 °C are assigned to isolated GaS4 tetrahedral units.5GaS4 has been reported,14 but not its crystal structure. Among the materials with the composition of 5Li2S·1M2S3 , only the crystal structure of Li5AlS4 has been analyzed in detail.13 The similarity of the XRD patterns of Li5AlS4 and Li5GaS4 was exploited to identify the crystal structure of Li5GaS4. The Rietveld refinement results for Li5GaS4 are presented in 5GaS4 is shown in 5GaS4 has the tetrahedral sites of lithium and gallium, and the octahedral site of lithium. In the Rietveld refinement of the XRD pattern of the HT-600 °C sample, the parameters reported for Li5AlS4 (P21/m (space group No. 11), a = 6.2488 Å, b = 7.8369 Å, c = 6.8583 Å, β = 90.333°) were used as the initial structural parameters, and then the parameters were refined using the Le Bail method. In the Rietveld refinement, the occupancy of all atoms and the atomic displacement parameters of Li were not refined. The full profile and Rietveld fitting of Li5GaS4 clearly reveal that the refined structure is almost accurate except for the difference in peak intensity at about 28°, which is probably due to the partial occupancy of gallium at the lithium site. Further analysis by neutron diffraction or single crystal X-ray diffraction is required to determine the lithium and gallium occupancy in detail.To date, only the conductivity of Li5GaS4 samples. At the composition of Li5GaS4, the conductivities differed according to the heating temperature. The milled sample showed the highest conductivity of 2.2 × 10−5 S cm−1 at 25 °C among the three prepared samples. The ionic conductivities of HT-420 °C and HT-600 °C at 25 °C were 8.1 × 10−7 and 2.1 × 10−8 S cm−1, respectively. The activation energies of the milled sample, HT-420 °C, and HT-600 °C were calculated to be 37, 44, and 47 kJ mol−1, respectively.5GaS4 samples , respectively.31 The cation sites of the antifluorite-type structure seem to have a high tolerance to the size of the cations. Such a cation-disordered phase has been previously reported for Li4SnS4 and Li2TiS3.24,32 In the crystal structure of hexagonal Li4SnS4, the tetrahedral sites are occupied by Li+ (rionic (n = 4): 0.59 Å) and Sn4+ (rionic (n = 4): 0.55 Å). In the mechanochemically synthesized Li2TiS3, the octahedral sites are occupied by cations of different sizes, viz., Li+ (rionic (n = 6): 0.76 Å) and Ti4+ (rionic (n = 6): 0.605 Å). These results indicate that cation disorder is possible not only in a structure with cations of similar sizes but also in structures containing cations of different sizes prepared by the mechanochemical process. Thus, the mechanochemical process is effective in the preparation of disordered structures, and the obtained disordered structures are metastable and have faster ionic conduction than the thermodynamically stable phases. The milled Li5GaS4 sample with a metastable crystal structure has higher conductivity (2.2 × 10−5 S cm−1) than the heated samples with a stable crystal structure (2.1 × 10−8 S cm−1) at 25 °C, as shown in 5GaS4 sample are broad, and they are mainly due to small crystallite size and/or disordered structure of the metastable phase. The sample possibly includes amorphous phase, which may contribute to the high conductivity of the milled Li5GaS4 sample.In the XRD patterns of the prepared Li samples , the pea Li5GaS4  because 5GaS4 crystal, the structural parameters were refined using the parameters of Li5AlS4. The lattice volumes of Li5GaS4 and Li5AlS4 are 337.135 and 335.8537 Å3, respectively. Although the difference between the cation radii of Ga3+ (0.47 Å) and Al3+ (0.39 Å)31 for tetrahedral coordination is large, the difference in their volumes is small. This assumption is reasonable considering the packed structure of the anions and cations. If we consider the ions as rigid spheres for simplicity, the critical ionic radius ratio for tetrahedral coordination (rcation/ranion) is 0.225. In the MS4 tetrahedral unit, the critical cation radius is 0.41 Å, when the anion radius of S2− is 1.84 Å.31 The critical cation radius is larger than the radius of Al3+, and the tetrahedral structure of AlS4 is unstable, according to simple numerical calculations. However, in fact, the tetrahedral unit is formed because of the distortion of the tetrahedral symmetry and the distortion of the electron clouds of the sulfide anions. The Ga–S and Al–S distances are 2.31 and 2.28 Å in the same tetrahedral unit, respectively. The volume of GaS4 tetrahedra is 6.34 Å3, larger than that of AlS4 tetrahedra (6.04 Å3). The crystal structure of Li5GaS4 is illustrated in 4, LiS4, and LiS6) in Li5GaS4 is the same as that in Li5AlS4. The crystal of Li5GaS4 consists of two layers, the MS4  layer and LiS6 layer, which are stacked alternately. All the tetrahedral interstices are occupied by Li or Ga in the MS4 layer, while all the octahedral interstices are occupied by Li in the LiS6 layer. In these crystals with completely filled sites, the ionic conductivity is usually low.In the structural analysis of the stable Li5GaS4 simultaneously has the advantage of high lithium content and the disadvantage of fully occupied sites. The conductivity of Li5GaS4 HT-600 °C is 2.1 × 10−8 S cm−1 at 25 °C. Note that Li5GaS4 has been previously reported to have a low conductivity of 5 × 10−8 S cm−1 at 100 °C.14 In comparison, the conductivity of HT-600 °C (monoclinic) at 100 °C, as estimated using the Arrhenius equation, is ∼20 times higher at 9.8 × 10−7 S cm−1.14 Compared to those of other stoichiometric thio-LISICON materials, the conductivity of monoclinic Li5GaS4 is lower; for instance, it is lower than those of γ-Li3PS4 (3 × 10−7 S cm−1),10 Li4SiS4 (5 × 10−8 S cm−1),11 Li4GeS4 (3 × 10−7 S cm−1),14 and Li4SnS4 (7 × 10−5 S cm−1),25 but higher than those of Li5AlS4 (9.7 × 10−9 S cm−1 at 50 °C)13 and Li3SbS4 (4.8 × 10−9 S cm−1).33 The differences in the conductivities is due to the lithium content, vacancy of lithium sites, and central cation–sulfide anion interaction. Understanding the differences in the conductivities of thio-LISICON is challenging because of various factors, such as the differences in their ductility and relative density of pellets. The HT-420 °C sample, which has a mixed structure consisting of the antifluorite-type and monoclinic crystals, shows a conductivity of 8.1 × 10−7 S cm−1, which is higher than that of HT-600 °C. This results from the precipitation of the metastable phase. Thus, among the three samples prepared in this study, the as-milled sample with the metastable antifluorite-type crystal phase has the highest conductivity, while the HT-600 °C sample with the stable monoclinic crystal phase has the lowest conductivity. The results clearly indicate that the antifluorite-type crystal is more suitable for ionic conduction than the monoclinic crystal.In crystalline ionic conductors, the site vacancy and number of carriers are important for fast ionic conduction. Considering the ionic conduction in the crystal structure, monoclinic Li5GaS4 solid electrolyte was prepared by a mechanochemical process and subsequently transformed into a stable Li5GaS4 solid electrolyte by heat treatment. The mechanochemically processed sample had the metastable antifluorite-type phase. When heated at 600 °C, the phase transformed to the stable monoclinic one, similar to that of Li5AlS4. The conductivity of the milled sample (metastable antifluorite-type phase) was determined to be 2.1 × 10−5 S cm−1 at 25 °C, which is three orders of magnitude higher than that of the heated sample with the stable phase. Thus, it is concluded that the metastable phase is a more suitable structure for ionic conduction than the stable phase at the composition of Li5GaS4. The results of this study extend research toward understanding sulfide electrolytes with cation-disordered metastable phases and cation-ordered stable phases, and contribute to the development of solid electrolytes with high ionic conductivity.In this study, sulfide antifluorite-type structure is proposed as a new flamework for ionic conduction. A metastable LiT. K., A. S., and A. H. designed the experiments and wrote the paper. T. K. synthesized and characterized the electrolytes. T. K. and C. H. performed the crystal analysis. A. S., T. M., and A. H. supervised the study. All of the authors discussed the results and commented on the manuscript.There are no conflicts to declare.