A 3D Cd(II) MOF of tetracarboxylate and tris(benzimidazole) ligands: Luminescence sensing properties

A new 3D Cd(II) MOF based on tetracarboxylic acid and tris-benzimidazole ligands was reported. The Cd(II) MOF shows a 4-connected mog -net structure and exhibits selective sensing toward Fe 3+ and Cr 2 O 7 2− in water. • A Cd(II) MOF of tetracarboxylic acid and tris-benzimidazole ligands is described. • MOF 1 shows a 3D 4-connected mog -net. • MOF 1 exhibits selective sensing toward Fe 3+ and Cr 2 O 7 2− . A tris-benzimidazole ligand, 1,3,5-tris(benzimidazol-1-ylmethyl)-2,4,6-trimethylbenzene (tbimb), and 3,3′,4,4′-biphenyltetracarboxylic acid (H 4 bptc) were selected as organic ligands to construct a new Cd(II) MOF under hydrothermal condition, [Cd(bptc) 0.5 (tbimb)(H 2 O)]·H 2 O ( 1 ). In the crystal structure of 1 , the Cd(II) centers were connected by bptc 4− and tbimb ligands to generate a 3D framework, which shows a 4-connected mog -net with point symbol of (4·6 4 ·8) 2 (4 2 ·6 2 ·8 2 ). UV–Vis spectrum of 1 shows two bands at 236 and 304 nm. Thermogravimetric and powder X-ray diffraction analyses indicate MOF 1 has good stability. The solid state photoluminescence of 1 shows the emission peak at 358 nm when it was excited at 291 nm. Furthermore, the luminescent quenching experiments suggest MOF 1 exhibits good selectivity and sensitivity to detect Fe 3+ and Cr 2 O 7 2− in water.