Copper(II) and zinc(II) complexes with Schiff-base ligands derived from salicylaldehyde and 3-methoxysalicylaldehyde: Synthesis, crystal structures, magnetic and luminescence properties

The following Schiff bases were employed as ligands in synthesizing copper(II) and zinc(II) complexes: N[(2-pyridyl)-methyl]-salicylimine (Hsalampy), N-[2-(N,N-dimethyl-amino)-ethyl]-salicylimine (Hsaldmen), and N-[(2-pyridyl)-methyl]-3-methoxy-salicylimine (Hvalampy). The first two ligands were obtained by reacting salicylaldehyde with 2- aminomethyl-pyridyne and N,N-dimethylethylene diamine, respectively, while the third one results from the condensation of 3-methoxysalicylaldehyde with 2- aminomethylpyridine. Four new coordination compounds were synthesized and structurally characterized: [Cu(salampy)(H2O)(ClO4)] 1, [Cu-2(salampy)(2)(H(2)trim)(2)](2) (H(2)trim = the monoanion of the trimescic acid), [Cu-4(valampy)(4)](ClO4)(4) center dot 2CH(3)CN 3, and [Zn-3(saldmen)(3)(OH)](ClO4)(2) center dot 0.25H(2)O 4. The crystal structure of 1 consists of supramolecular dimers resulted from hydrogen bond interactions established between mononuclear [Cu(salampy)(H2O)(ClO4)] complexes. Compound 2 is a binuclear complex with the copper ions connected by two monoatomic carboxylato bridges arising from two molecules of monodeprotonated trimesic acid. The crystal structure of 3 consists of tetranuclear cations with a heterocubane {Cu4O4} core, and perchlorate ions. Compound 4 is a trinuclear complex with a defective heterocubane structure. The magnetic properties of complexes 1-3 have been investigated. Compound 4 exhibits solid-state photoluminescence at room temperature. (C) 2008 Elsevier B.V. All rights reserved.