Aminopyridine derivatives controlled the assembly and various properties of Cu–BTC metal–organic frameworks

Abstract

Three Cu(II) metal–organic frameworks (MOFs) based on 1,3,5-benzenetricarboxylic acid (H₃BTC) and three aminopyridine derivatives with different lengths and coordination groups, namely [Cu₂(3-azpy)(HBTC)(H₂BTC)(μ₃-OH)(H₂O)₂] (1), [Cu₂(3-ppca)(BTC)(H₂O)₃]·H₂O (2), [Cu₂(3-ebpba)(BTC)(μ₃-OH)] (3) [3-azpy = 3,3′-azopyridine, 3-ppca = N-(pyridin-3-yl)pyrazine-2-carboxamide, 3-ebpba = (E)-4,4′-(ethene-1,2-diyl)bis(N-pyridin-3-yl)benzamide)], have been hydrothermally synthesized and structurally characterized by elemental analyses, IR, PXRD, TG and single crystal X-ray diffraction analyses. The title MOFs display versatile structural features with 2D and 3D frameworks. Complex 1 exhibits a 2D layer, which is constructed from the 3-azpy bridging ligands and a 1D ladder-like Cu–BTC chain with tetranuclear copper clusters. The 3-azpy was in situ transformed from 3-aminopyridine under the hydrothermal conditions. Complex 2 shows a rare 3D framework, which features a (3,3,3,3)-connected topology with a Schläfli symbol of {8·10·12}₂{8²·10}₂. Complex 3 exhibits a (3,8)-connected {4·6²}₂{4²·6²²·7·8³} topology based on tetranuclear copper clusters. The influence of aminopyridine-based ligands on the structures and properties of the title complexes has been discussed. The electrocatalytic and photocatalytic properties of complexes 1–3 have also been investigated in detail.