Coordination polymers with a semi-rigid spacer ligand in a mixed system: Roles of benzene-1,3,5-tricarboxylate anions

Reactions of divalent metal salts with N,N'-bis(3-pyridyl)terephthalamide (L) and benzene-1,3,5-tricarboxylic acid (1,3,5-H3BTC) under hydro(solvo)thermal conditions afforded five coordination polymers, {[Cd(L)(1,3,5-HBTC)]center dot 2H(2)O}(n), 1, {[Cu(L)(1,3,5-HBTC)]center dot H2O}(n), 2, {[Zn(L)(1,3,5-HBTC)]center dot 2H(2)O}(n), 3, {(H2L)(0.5)[Ni(L)(1,3,5-BTC)(H2O)(2)]center dot H2O center dot}(n), 4, and {[Ni-1.5(L)(1.5)(1,3,5-BTC)(CH3OH)(2)]center dot 3CH(3)OH}(n), 5, which have been structurally characterized by using single-crystal X-ray diffraction. Complexes 1 - 3 adopt the 3,5-connected 2D nets with the {4(2).6(7).8}{4(2).6}-3,5L2 topology, whereas 4 shows a 1D column with the 2,4C6 topology and 5 exhibits a 2D double layer with the hexagonal channels and the 3,4,4L35 topology, indicating the significant effect of the cocrystallized solvent molecules on the structural diversity of 4 and 5. Moreover, complex 5 can be transformed to 4 irreversibly under solvothermal condition, which can be ascribed to the various coordination modes of the benzene-1,3,5-tricarboxylate anions. The thermal properties of complexes 1-5 and the luminescent properties of 1 and 3 are also discussed. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Five coordination polymers were synthesized using divalent metal salts and characterized by single-crystal X-ray diffraction. The structural diversity of the polymers was influenced significantly by co-crystallized solvent molecules, and some complexes demonstrated irreversible transformation under solvothermal conditions. Additionally, the thermal and luminescent properties of the complexes were discussed.