Assembly, photocatalytic and fluorescence properties of three new coordination complexes of zinc(II) and nickel(II) with two kinds of flexible bis(pyridyl)-bis(amide) ligands

Abstract

Three new coordination complexes [Zn(btec)0.5(L1)0.5(H2O)]n (1), [Ni(H2btec)(L1)(H2O)2]n (2), and {[Ni(btec)0.5(L2)(H2O)3]·2H2O}n (3) [H4btec = 1,2,4,5-benzenetetracarboxylic acid), L1 = N,N′-bis(3-pyridyl)adipamide, L2 = N,N′-bis(3-pyridyl)octanediamide] have been obtained under hydrothermal conditions. Single-crystal X-ray diffraction analysis has revealed that complex 1 has a layer structure based on [Zn(btec)0.5]n ribbons and the μ2-bridging ligands L1. Complex 2 possesses a layered framework constructed by [Ni(H2btec)]n linear chains and [Ni(L1)]n wave-like chains. Complex 3 forms layers based on [Ni(L2)]n helical chains and μ2-bridging L2 ligands, representing an interesting 4-fold interpenetrating 2D braided framework. The three different 2D frameworks exhibit 3,4-connected {4.62}2{42.62.82} topology for 1, 4-connected {44.62} topology for 2 and 3-connected {63} topology for 3. Their adjacent layers are further linked by hydrogen bonding interactions to generate 3D supramolecular structures. The differences in the nature of both the metal ions and the organic ligands lead to various coordination modes in the final structures. The photocatalytic activities and the fluorescence properties of complexes 1–3 were investigated.