Crystal Structures and Luminescence of Two Cadmium‐Carboxylate Cluster‐based Compounds with Mixed Ligands

Reactions of Cd(NO3)2·4H2O with 2-quinolinecarboxylic acid (H-QLC) in the presence of 1,4-benzenedicarboxylic acid (H2-BDC) or 1,3,5-benzenetricarboxylic acid (H-BTC) in DMF/H2O solvent afforded two compounds, namely, [Cd(QLC)(BDC)1/2(H2O)]n (1) and [Cd(QLC)(BTC)1/3]n (2). Both compounds are two-dimensional (2D) frameworks but feature different cadmium-carboxylate clusters as a result of the presence of the polycarboxylate ligands with different geometries and coordination preference. The dinuclear Cd2(QLC)2 units in 1 are bridged by the pairs of bridging water ligands to give a one-dimensional (1D) chain, which is further linked by the second ligand of BDC2– to form a 2D structure. Compound 2 is constructed from unique hexanuclear macrometallacyclic Cd6(QLC)6 clusters, which are linked by the surrounding BTC3– ligands to generate a 2D structure. Photoluminescence studies showed both compounds exhibit ligand-centered luminescent emissions with emission maxima at 405 and 401 nm, respectively.