In situ construction of two substituent-related dinuclear zinc(II) azaheterocyclic complexes from two simple Schiff base ligands with pyridyl terminal groups

Abstract

Two interesting dinuclear Zn(II)-compounds Zn2L3Cl4 (1) and Zn2L4Cl4 (2) were synthesized through the in situ zinc-induced reaction of simple pyridyl terminated (L1/L2)Schiff base ligands with ZnCl2 in the mixture solvents of DMF and pyridine at 80°C for three days (where L1=N-(2-pyridyl-methyl)-pyridine-2-carbaldimine, L2=1-(pyridin-2-yl)-N-(pyridin-2-yl-methylene)ethanamine, L3=2,3,5,6-tetra-(pyridin-2-yl)pyrazine, L4=1,2-di(pyridin-2-yl)-bis(1-(pyridin-2-yl)-ethylidene)ethane-1,2-diamine). The elemental analysis (EA) and IR results reveal that in situ formation of one new ligand L3 in 1 involves two CC coupling reactions from two molecular L1 featuring H atom in α-carbon of CN moiety, while in situ formation of another new ligand L4 in 2 involves one CC coupling reaction from L2 featuring –CH3 group in α-carbon of CN moiety. Obviously, different molecular structures between 1 and 2 closely related to the different substituents in simple Schiff base ligands. Moreover, the fluorescent properties of compounds 1 and 2 were also studied.