Two new coordination polymers with multiform helical features based on flexible dithioether ligands and CuCN: from self-penetrating to 3-fold interpenetrating structures

Abstract

The solvothermal reactions of CuCN with two structure-related flexible 4-pyridyl dithioether ligands, bis(4-pyridylthio)methane (L1) and 1,2-bis(4-pyridylthio)ethane (L2), generated two novel three-dimensional (3D) coordination polymers: [(CuCN)₅(L1)₂]_n (1) and [(CuCN)₃(L2)]_n (2), respectively. Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric analyses. Complex 1 is constructed by the interconnection of CuCN layers with L1 pillars to form an interesting self-penetrating 12³ topological network with characteristic of four distinct helical chains. In 2, each L2 acting as a quadridentate μ₃-bridge connects Cu atoms from three uncommon meso-helical CuCN chains, to give 3D framework containing 1D tubes constructed by two types of helical chains with opposite chirality. 2 exhibits a 3-fold interpenetrating network with a rare (6²·10)₂(6·10²) topology. In addition, the solid state samples of 1 and 2 exhibited different luminescent properties at room temperature.