Microwave-assisted synthesis, crystal structure and fluorescence of novel coordination complexes with Schiff base ligands

The reactions of the ligand 2-hydroxy-3-methoxy-benzaldehyde (Hhmb) and methylamine, or 25% ammonia with varied metal salts of Zn(II), Mn(II), Ni(II) result in formation of three new coordination complexes, [M-7(OH)(6)(mimmp)(6)]X-2 (M = Zn, X = NO3- (1); M = Mn, X = ClO4-), [Ni(immp)(2)]center dot(H2O)(2) (3) (mimmp is the anion of 2-methoxy-6-methyliminomethyl-phenolic and immp is the anion of 2-iminomethyl-6-methoxyphenolic) and their structures were determined by X-ray crystallography. Complexes 1 and 2 with octahedral metal centers have similar disperse heptanuclear clusters, while complex 3 displays a 3-D network structure through N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds containing an interesting six-membered water ring; Herein, the Ni(II) has planar coordination geometry. Ligand mimmp acts as a tetradentate bridging ligand in 1 and 2 while ligand immp acts as bidentate chelated ligand in 3. The photoluminescent properties of Hmimmp ligand and complexes 1 and 2 were studied in the solid state at room temperature. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.