Syntheses, crystal structures, and properties of five mixed-ligand coordination polymers based on novel quaterphenyl-2,5,2′,5′-tetracarboxylic acid ligand

Abstract

Solvothermal reactions of aromatic quaterphenyl-2,5,2′,5′-tetracarboxylic acid (H₄qptc) ligand and transitional metal cations of M^II (M = Co, Ni, Mn, Cu, Zn) in the presence of 1,10-phenanthroline (phen) afford five new coordination polymers (CPs), namely, {[M(H₂qptc)(phen)(H₂O)₂]·2H₂O}_n (M = Co (1), Ni (2)), [Mn(qptc)_0.5(phen)(H₂O)]_n (3), [Cu(qptc)_0.5(phen)]_n (4) and [Zn₃(Hqptc)₂(phen)₂(H₂O)₂]_n (5). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric (TG) analyses. Complexes 1 and 2 are isostructures and each displays a one-dimensional (1D) zigzag chain, which further forms a 2D supramolecular architecture via inter-chain π⋯π interactions. Complex 3 possesses a (3,6)-connected CdI₂ layered architecture incorporating left- and right-handed helical chains. Complex 4 exhibits a 3D porous structure with rare (3,6)-connected ant topology. Complex 5 shows a 3D (3,4,5)-connected network with (4².6)₂(4³.6².8)(4⁵.6⁴.8)₂ topology. The results show that the conformations and coordination modes of H₂qptc²⁻/qptc⁴⁻ ligand are crucial factors for the formation of the different structures. Moreover, the photoluminescence of 5 has been investigated.