Series of Cadmium(II) Coordination Polymers Based on a Versatile Multi-N-Donor Tecton or Mixed Carboxylate Ligands: Synthesis, Structure, and Selectively Sensing Property

Abstract

Five Cd(II) metal–organic frameworks (MOFs), [Cd(HL) 2 ] ( 1 ), [Cd(HL) 2 (H 2 O) 2 ] ( 2 ), [Cd 3 (HL) 2 (obda) 2 ] ( 3 ), [Cd 2 (HL) 2 (ohmbda)(DMA)(H 2 O)] ( 4 ), and [Cd 2 (HL)(btc)(H 2 O) 2 ]·3H 2 O ( 5 ), were prepared by reactions of Cd(NO 3 ) 2 ·4H 2 O with 1-(1 H -imidazol-4-yl)-4-(4 H -tetrazol-5-yl)benzene (H 2 L) or mixed carboxylate ancillary ligands of 1,2-benzenedicarboxylic acid (H 2 obda), 5-hydroxy-1,3-benzenedicarboxylic acid (H 2 ohmbda), and 1,3,5-benzenetricarboxylic acid (H 3 btc), respectively. Their structures have been characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy (IR), thermogravimetric analysis, and powder X-ray diffraction. Compounds 1 and 2 are supramolecular isomeric frameworks without consideration of the solvent molecules. Complex 1 exhibits a binodal (3, 5)-connected two-dimensional (2D) layer structure with the point (Schläfli) symbol of (5 2 ·6)(5 5 ·6 4 ·7), while complex 2 shows a 2D + 2D → 3D (three-dimensional) framework. Complex 3 is a (3, 5, 6)-connected tetranodal 3D net with the point (Schläfli) symbol of (4·8 2 ) 2 (4 5 ·6·8 4 ) 2 (4 5 ·6 5 ) 2 (4 8 ·6 6 ·8). Compound 4 is a (3, 3, 8)-connected trinodal 3D net with the point (Schläfli) symbol based on a binuclear [Cd 2 N 2 O] subunit, while 5 is a 2-nodal (3, 4)-connected 2D V 2 O 5 -type network based on [Cd 2 N 2 (COO) 2 ] SBU. The studies of molecular sensing properties show that the luminescent MOFs can be employed as fluorescent sensors for the detection of Fe 3+ and nitro compounds. Compound 1 and 3 exhibit quenching responses for Fe 3+ in dimethylformamide solution with detection limits of 2.3 × 10 –6 an...

A Series of Metal–Organic Frameworks: Syntheses, Structures and Luminescent Detection, Gas Adsorption, Magnetic Properties

“…Apparently, the polarity of the solvent has a great effect on the fluorescence intensity, which follows the sequence of DMF > DEF ≈ DMA > H 2 O > MeOH ≈ CH 3 CN > DMSO ≈ CH 2 Cl 2 > EtOH > Et 2 O ≈ CB ≫ NB (Figure ). The fluorescent material of MOF 1 shows high fluorescence intensity when dispersed in a strong dipole moment solvent such as DMF, DEF, DMA, H 2 O, and MeOH . However, the organic solvent of NB leads to complete fluorescence quenching, which could be attributable to the electron and energy transfer between electron-deficient NB molecules and host framework .…”

Metal–organic framework based on flexible ligands and CoII–CoII–CoII system: selective gas adsorption and magnetic properties

“…[11][12][13][14][15] Ligands containing carboxyl and imidazole have been fully studied for many years, and there are more and more studies on using mixed ligands to construct MOF structures. [16][17][18][19][20] However, only a few studies on the construction of MOFs with flexible mixed ligands have been reported at the same time. 21,22 We chose a flexible carboxylic acid ligand and flexible imidazole ligand to construct novel MOFs based on the following considerations.…”

Crystal Structures, Hirshfeld Surfaces, and Thermal Study of Isostructural Polymeric Ladders of La(III) and Sm(III) Coordination Compounds with 4,4’-Bipyridine and Dibromoacetates

“…These compounds find applications in many different areas of everyday life, industry, and science. Some of the examples are sensors and biosensors [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ], electronic and optoelectronic devices [ 9 , 10 ], chemical catalysts, and photocatalysts [ 11 , 12 , 13 , 14 , 15 , 16 ]. Some coordination polymers can be used to remove harmful substances [ 17 , 18 , 19 , 20 ] or to capture and entrap other molecules [ 21 , 22 ].…”