Syntheses, structures, and luminescence properties of four metal–organic polymers with undocumented topologies constructed from 3,5-bis((4′-carboxylbenzyl)oxy)benzoate ligand

Abstract

Solvothermal reactions of one semirigid tricarboxylic acid and transition metal cations in the absence or presence of 1,4-bis(1H-imidazol-4-yl)benzene (1,4-bib) afford four coordination polymers, namely, [Cd(Hbcb)]_n (1), and [M(Hbcb)(1,4-bib)]_n (M = Cd (2), Mn (3), Fe (4)) (H₃bcb = 3,5-bis((4′-carboxylbenzyl)oxy)benzoic acid). 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. Structural analysis revealed that complex 1 exhibits an intriguing [Cd(COO)₂]_n tube-like chain based 3D framework with unprecedented 6-connected (4⁸·6⁷) topology. Complexes 2–4 show isomorphism and show new 3D (3,5)-connected frameworks with the point Schläfli symbol of (4·6·8)(4·6⁴·8⁵) based on the [M(COO)]_n chain. Moreover, the photoluminescence properties of 1 and 2 have been investigated in the solid state at room temperature.