Dicarboxylate-Induced Structural Diversity of Luminescent Zn(II)/Cd(II) Metal-Organic Frameworks Based on the 2,5-Bis(4-pyridyl)thiazolo[5,4-d]thiazole Ligand

Constructed from rigid 2,5-bis(4-pyridyl)thiazolo[5,4-d]thiazole (Py(2)TTz) and various dicarboxylic acids [2-methyl-1,4-benzenedicarboxylic acid (2-CH3-H2BDC), 5-methyl-1,3-benzenedicarboxylic acid (5-CH3-H2BDC), 2,5-dimethyl-1,4-benzenedicarboxylic acid (2,5-di-CH3-H2BDC), 2,5-dihydroxyl-1,4-benzenedicarboxylic acid (2,5-di-OH-H2BDC), 1,4-naphthalenedicarboxylic acid (1,4-H2NDC), and 2,6-naphthalenedicarboxylic acid (2,6-H2NDC)], nine novel Zn(II)/Cd(II) MOFs have been synthesized under solvothermal conditions. They possess diverse structures, which mainly result from the different shapes and sizes of the auxiliary dicarboxylate ligands. Linear dicarboxylate ligands (2-CH3-BDC, 2,5-di-CH3-BDC, 1,4-NDC, 2,6-NDC) generate 3D multi-fold interpenetrated structures, while the V-shaped dicarboxylate ligand (5-CH3-BDC) affords a 2D layer structure. However, linear 2,5-di-OH-BDC results in a 2D layer structure owing to the influence of the hydroxy group. Luminescence properties of compounds 1-9 have been investigated systematically. They display structure-dependent emission ranging from blue to blue-white and blue-green.