Syntheses, Structures, and Photoluminescence of a Series of Three-Dimensional Cd(II) Frameworks with a Flexible Ligand, 1,5-Bis(5-tetrazolo)-3-oxapentane

Six novel Cd II -based metal−organic frameworks with a flexible ligand 1,5-bis(5-tetrazolo)-3-oxapentane) (H 2 btz), [Cd 5 (N 3 ) 6 (btz) 2 ] n ( 1 ), [Cd 5 X 2 (N 3 ) 4 (btz) 2 ] n (X = Cl ( 2 ), Br ( 3 )), [Cd 3 (N 3 ) 2 (btz) 2 ] n ( 4 ), and [Cd 3 X 2 (btz) 2 ] n (X = Cl ( 5 ), Br ( 6 )), have been successfully synthesized under hydrothermal reactions and structurally characterized by single-crystal X-ray diffraction. The H 2 btz ligands in the complexes 1 − 4 can be in situ generated from the [2 + 3]-cycloaddition reaction of the precursor bis(2-cyanoethyl)ether (BCEE) and NaN 3 under Cd II -catalyzed. Single-crystal X-ray diffraction analysis revealed that all of the complexes 1 − 6 displayed rich three-dimensional (3D) frameworks constructed from Cd 2+, btz 2− ligand, and bridging anions. It has been found that the ingenious changes of anions finally lead to the structural diversity in 1 − 6, such as N 3 − for 1 and 4, N 3 − and Cl − for 2, N 3 − and Br − for 3, Cl − for 5, and Br − for 6 . Additionally, the X-ray powder diffraction (XRPD), thermal stability, and the photoluminescence properties at room temperature in the solid state for 1 − 6 have also been studied.