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

Abstract

Hydrothermal reactions of Zn(NO₃)₂·6H₂O or CdCl₂·2.5H₂O 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, [Zn₂(5-Me-1,3-BDC)₂(bimpa)₂]_n (1), {[Cd₂(5-Me-1,3-BDC)₂(bimpa)(H₂O)₄]·H₂O}_n (2), {[Zn(5-tb-1,3-BDC)(bimpa)]·2H₂O}_n (3) and {[Cd(5-tb-1,3-BDC)(bimpa)]·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 (6⁵·8) layers (3) and 2D layers constructed by 1D tubes (4), which are further extended into two 3D supramolecular architectures through weak hydrogen-bonding and π⋯π 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.