Amending the anisotropy barrier and luminescence behavior of heterometallic trinuclear linear [M(II) -Ln(III) -M(II) ] (Ln(III) =Gd, Tb, Dy; M(II) =Mg/Zn) complexes by change from divalent paramagnetic to diamagnetic metal ions.
The sequential reaction of a multisite coordinating compartmental ligand [2-(2-hydroxy-3-(hydroxymethyl)-5-methylbenzylideneamino)-2-methylpropane-1,3-diol] (LH4 ) with appropriate lanthanide salts followed by the addition of [Mg(NO3 )2 ]⋅6 H2 O or [Zn(NO3 )2 ]⋅6 H2 O in a 4:1:2 stoichiometric ratio in the presence of triethylamine affords a series of isostructural heterometallic trinuclear complexes containing [Mg2 Ln](3+) (Ln=Dy, Gd, and Tb) and [Zn2 Ln](3+) (Ln=Dy, Gd, and Tb) cores. The formation of these complexes is demonstrated by X-ray crystallography as well as ESI-MS spectra. All complexes are isostructural possessing a linear trimetallic core with a central lanthanide ion. The comprehensive studies discussed involve the synthesis, structure, magnetism, and photophysical properties on this family of trinuclear [Mg2 Ln](3+) and [Zn2 Ln](3+) heterometallic complexes. [Mg2 Dy](3+) and [Zn2 Dy](3+) show slow relaxation of the magnetization below 12 K under zero applied direct current (dc) field, but without reaching a neat maximum, which is due to the overlapping with a faster quantum tunneling relaxation mediated through dipole-dipole and hyperfine interactions. Under a small applied dc field of 1000 Oe, the quantum tunneling is almost suppressed and temperature and frequency dependent peaks are observed, thus confirming the single-molecule magnet behavior of complexes [Mg2 Dy](3+) and [Zn2 Dy](3+) .
['Das|Sourav|S|', 'Bejoymohandas|K S|KS|', 'Dey|Atanu|A|', 'Biswas|Sourav|S|', 'Reddy|M L P|ML|', 'Morales|Roser|R|', 'Ruiz|Eliseo|E|', 'Titos-Padilla|Silvia|S|', 'Colacio|Enrique|E|', 'Chandrasekhar|Vadapalli|V|']
luminescence heterometallic complexes single-molecule magnets coordination chemistry magnetic properties photochemistry