Tuning Structural Topologies of Three Photoluminescent Metal–Organic Frameworks via Isomeric Biphenyldicarboxylates

Three new cadmium compounds, [Cd­(2,4′-bpdc)­(bib)0.5] (1; 2,4′-bpdc = biphenyl-2,4′-dicarboxylate and bib = 1,4-bis­(2-methyl-imidazol-1-yl)­butane), {[Cd2(3,4′-bpdc)2(bib)1.5(H2O)]n·H2O}n (2; 3,4′-bpdc = biphenyl-3,4′-dicarboxylate), and [Cd (4,4′-bpdc)­(bib)] (3; 4,4′-bpdc = biphenyl-4,4′-dicarboxylate), have been successfully synthesized by the assembly of Cd2+ ions, bib ligands, and isomeric bpdc ligands, respectively. This paper presents a comparative study on the tuning of structural topologies using three isomers of biphenyldicarboxylates as bridging ligands. Compound 1 based on 2,4′-bpdc features a three-dimensional (3D) framework with 6-connected mab topology. Compound 2 based on 3,4′-bpdc is another 3D framework, but it possesses a rare 3-fold interpenetrating 4,6-connected fsh net, while compound 3 based on linear 4,4′-bpdc shows unusual 2D → 3D parallel polycatenation of (4,4) layers. Furthermore, the luminescent properties of three compounds are investigated in the solid state.