Structural diversity, luminescence and photocatalytic properties of six coordination polymers based on designed bifunctional 2-(imidazol-1-yl)terephthalic acid

Abstract

Six coordination polymers (CPs), {[M(ITA)]·0.5H₂O}_n (M = Zn 1, M = Mn 2), {[Zn(ITA)(bib)_0.5]·1.5H₂O}_n (3), {[Ni(ITA)(bib)_0.5(H₂O)₃]·H₂O}_n (4), {[Zn(ITA)(bimb)_0.5]·0.5H₂O}_n (5) and [Cd(ITA)(bimb)_0.5(H₂O)₂]_n (6), have been derived from the designed bifunctional 2-(imidazol-1-yl)terephthalic acid (H₂ITA) with or without bis(imidazole) linkers (bib = 1,4-bis(imidazol-1-yl)benzene, bimb = 1,4-bis(imidazol-1-ylmethyl)benzene). X-Ray single-crystal diffraction analysis reveals that complexes 1 and 2 are isomorphic with the same 3D (4)-connected {4·6³·8²} net. Complex 3 features a 3D 2-fold interpenetrated (3,4)-connected fsc net with point symbol of {4·8²·10³}{4·8²}. Complex 4 displays a 2D 3-connected {6³)-hcb sheet, which can be further expanded into a 3D supramolecular network through hydrogen bonding interactions. Complex 5 exhibits an unprecedented 3D 2-fold interpenetrated (3,4)-connected dmc net with point symbol of {4·8²}{4·8⁵}. Complex 6 shows a 3D (3,4)-connected {4·8²·10³}{4·8²}-fsc net. Structural comparison reveals that not only the coordination preferences of metal ions but also the auxiliary bis(imidazole) linkers play crucial roles in the control of the final structures. Besides, the photoluminescence properties as well as the photocatalytic activities for the degradation of methylene blue (MB) under UV-vis light of 1, 3, 5 and 6 have been investigated.