Alkyl group-directed assembly of coordination polymers based on bis-(4-imidazol-1-yl-phenyl)-amine and their photocatalytic properties

Hydrothermal reactions of Zn(NO3)(2)center dot 6H(2)O or CdCl2 center dot 2.5H(2)O with bis-(4-imidazol-1-yl-phenyl)-amine (bimpa) and 5-methyl-1,3-benzenedicarboxylic acid (5-Me-1,3-H2BDC) or 5-tert-butyl-1,3-benzenedicarboxylic acid (5-tb-1,3-H2BDC) afforded four coordination polymers, [Zn-2(5-Me-1,3-BDC)(2)(bimpa)(2)](n) (1), {[Cd-2(5-Me-1,3-BDC)(2)(bimpa)(H2O)(4)]center dot H2O}(n) (2), {[Zn(5-tb-1,3-BDC)(bimpa)]center dot 2H(2)O}(n) (3) and {[Cd(5-tb-1,3-BDC)(bimpa)]center dot H2O} n (4). Complexes 1-4 were characterized by elemental analysis, IR, powder X-ray diffraction, and single-crystal X-ray diffraction. 1 exhibits a 4-fold interpenetrating 3D framework in which 1D curvilinear chains are interconnected by bimpa ligands. 2 can be considered as a 3D supramolecular architecture based on 2D entanglements which consist of 1D tubes in parallel interpenetration. 3 and 4, respectively, have 2D (6(5).8) layers (3) and 2D layers constructed by 1D tubes (4), which are further extended into two 3D supramolecular architectures through weak hydrogen-bonding and pi center dot center dot center dot pi interactions. The solid state luminescence and optical properties of 1-4 at ambient temperature were also investigated. A comparative study on their photocatalytic activity toward the degradation of methylene blue in polluted water was explored.