Syntheses, Crystal Structures and Properties of Coordination Polymers Built from a Semi-rigid Tripod Carboxylic Acid

By using a semi-rigid multidentate carboxylate linker 3,3',3 ''-(((2,4,6-trimethylbenzene-1,3,5-triyl)tris (methylene))tris(oxy))tribenzoic acid (H3L), four coordination polymers, namely, [Cd-3(L)(2)(H2O)(2)]center dot 5DMF center dot 6H(2)O}(n) (1), {[Co-3(L)(2)(H2O)(2)]center dot 2DMF center dot 6H(2)O} (2), {[Mn-3(L)(2)(H2O)(2)]center dot 3DMF center dot 6H(2)O}(n) (3), {[Zn-3(L)(2)(H2O)(2)]center dot 5DMA center dot 5H(2)O}(n) (4) were obtained and characterized by single crystal X-ray diffraction, thermogravimetric, elemental analysis, thermal analyses, IR spectra and fluorescence. Four compounds are isostructural with hourglass M-3 clusters and L3- ligands as secondary building units (SBUs) to form a pumpkin-shaped metalorganic nanocage, and possess a three-connected node (3,3,6)-connected 3D network. Compounds 1 and 4 exhibited strong photoluminescent emissions at room temperature with a peak at 385 nm, owing to a ligand-centered excited state. The emission intensities of the compound 1 varied upon contact with different solvents or analytes, exhibiting selective emission quenching responses towards nitroaromatics. CCDC: 1041419, 1; 1041420, 2; 1041421, 3; 1041422, 4.