A series of Cd(II) complexes with π-π stacking and hydrogen bonding interactions: Structural diversities by varying the ligands

Seven new Cd(II) complexes consisting of different phenanthroline derivatives and organic acid ligands, formulated as [Cd(PIP)(2)(dnba)(2) (1), [Cd(PIP)(ox)]center dot H2O (2), [Cd(PIP)(1,4-bdc)(H2O)]center dot 4H(2)O (3), [Cd(3-PIP)(2)(H2O)(2)]center dot 4H(2)O (4), [Cd-2(3-PIP)(4)(4,4'-bpdc)(H2O)(2)]center dot 5H(2)O (5), [Cd(3-PIP)(niP)(H2O)]center dot H2O (6), Piz (TIP)(4)(4,4'-bpdc)(H2O)(2)]center dot 3H(2)O (7) (PIP=2-phenylimidazo[4,5-f]1,10-phenanthroline, 3-PIP= 2-(3-pyridyl) imidazo[4,5-f]1,10-phenanthroline, TIP= 2-(2-thienyl)imidazo[4,5-f]1,10-phenanthroline, Hdnba=3,5-dinitrobenzoic acid. H(2)ox= oxalic acid, 1.4-H(2)bdc=benzene-1,4-dicarboxylic acid, 4.4'-H(2)bpdc= bipheny1-4, 4'-dicarboxylic acid, H(2)nip=5-nitroisophthalic acid) have been synthesized under hydrothermal conditions. Complexes 1 and 4 possess mononuclear structures; complexes Sand 7 are isostructural and have dinuclear structures; complexes 2 and 3 feature 1D chain structures; complex 6 contains ID double chain, which are further extended to a 3D supramolecular structure by pi-pi stacking and hydrogen bonding interactions. The N-donor ligands with extended it-system and organic acid ligands play a crucial role in the formation of the final supramolecular frameworks. Moreover, thermal properties and fluorescence of 1-7 are also investigated. (C) 2010 Elsevier Inc. All rights reserved.