Assembly, structures, photophysical properties and photocatalytic activities of a series of coordination polymers constructed from semi-rigid bis-pyridyl-bis-amide and benzenetricarboxylic acid

Abstract

A series of new metal(II)–organic coordination polymers, namely [Co(3-DPNA)(1,3,5-HBTC)]·2H₂O (1), [Ni(3-DPNA)_1.5(1,3,5-HBTC)(H₂O)₂] (2), [Cu(3-DPNA)(1,3,5-HBTC)]·H₂O (3), [Zn(3-DPNA)(1,3,5-HBTC)]·2H₂O (4), [Cd(3-DPNA)(1,3,5-HBTC)(H₂O)]·2H₂O (5), [Co(4-DPNA)(1,3,5-HBTC)]·4H₂O (6), [Ni(4-DPNA)(1,3,5-BTC)_2/3] (7), [Cu(4-DPNA)(1,3,5-BTC)_2/3] (8), [Zn(4-HDPNA)(1,3,5-BTC)] (9), [Cd(4-DPNA)(1,3,5-BTC)_1/3Cl] (10), have been purposefully synthesized under hydrothermal conditions [N¹,N⁴-di(pyridin-3-yl)naphthalene-1,4-dicarboxamide (3-DPNA) and N¹,N⁴-di(pyridin-4-yl)naphthalene-1,4-dicarboxamide (4-DPNA), 1,3,5-H₃BTC = 1,3,5-benzenetricarboxylic acid]. Complexes 1 and 4 exhibit similar 1D belt-like chains constructed from 1D left- and right-hand [Co-(3-DPNA)]_n helical chains and [Co-(1,3,5-HBTC)]_n linear chains. Complex 2 furnishes a 1D [Ni-(3-DPNA)_1.5]_n “loop + line” chain with 1,3,5-HBTC anions hanging on both sides. Complex 3 features a 2D sql network based on [Cu-(3-DPNA)]_nmeso-helical chains and [Cu-(1,3,5-HBTC)]_n linear chains. Complex 5 shows a 1D ladder-like chain constructed from [Cd-1,3,5-HBTC]_n linear chains and [Cd₂(3-DPNA)₂] loops. Complex 6 displays a 2D double sheet containing (H₂O)₈ clusters. Complexes 7 and 8 possess similar 3D (3,4)-connected frameworks with the (6³)₂(6⁴·8·10)₃ topology containing a dodecagon-shape cavity and a hexagonal cavity, respectively. Complex 9 shows a 2D network, in which one pyridine nitrogen atom of 4-DPNA was protonated. Complex 10 is a 3D (3,5)-connected framework with (3·4⁴·6³·8²)₃(6³) topology. All the 1D chains and 2D networks are further extended into 2D supramolecular sheets or 3D supramolecular frameworks through hydrogen-bonding interactions. The influence of metal(II) ions and N-donor ligands on the structures of the title compounds was investigated. The results suggest that the central metals with various coordination nature and the semi-rigid bis-pyridyl-bis-amide ligands with different coordination sites show a great effect on the structures of the title compounds. In addition, the fluorescence sensing properties of 4, 5, 9, and 10 and the photocatalytic activities of complexes 1–10 have been investigated in detail, and the results show that 5 possesses good fluorescence selectivity for different solvent molecules.