A flexible multidentate Schiff-base ligand having multifarious coordination modes in its copper(II) and cadmium(II) complexes

Abstract

A mononuclear complex, [CuL2]·2(CH3OH) (1), and two one-dimensional (1D) coordination polymers, {[Cu3L4(CH3OH)2]·(NO3)2}n (2) and [Cd(LH)2(N3)2]n (3), having a flexible multidentate Schiff-base ligand, 2-(3-(1H-imidazol-1-yl)propyliminomethyl)phenol (LH), with multifarious coordination modes have been obtained in different solvents and pH values. Another 1D cadmium(II) coordination polymer, [Cd(apimH)2Br3]n (4) (apim=(3-aminopropyl)imidazole), is also included for comparison. A four-coordinate square-planar Cu(II) center is formed in 1 where L serves as a bidentate N,O-chelating ligand, while two five-coordinate dinuclear Cu(II) centers and one six-coordinate mononuclear Cu(II) center are alternately arranged via two tridentate ligands in 2. In contrast, six-coordinate Cd(II) centers are constructed in 3 and 4, in the absence of a base, and they are bridged by double μ2 azide anions in an end-to-end way in 3 and alternate mono and triple μ2 bromine anions in 4. Furthermore, FT-IR, 1H NMR, UV–Vis and fluorescence spectral comparisons between LH and its metal complexes have been studied.