Chenggang Wang

Two Amino-Decorated Metal–Organic Frameworks for Highly Selective and Quantitatively Sensing of HgII and CrVI in Aqueous Solution

Two amino-decorated metal-organic frameworks have been constructed, which are the rare examples of MOF-based fluorescent probes targeting environmentally relevant guest species, such as Hg (II) and Cr (VI) ions in aqueous solution, with high selectivity and sensitivity. The possible sensing mechanism is also discussed.

Structures, photoluminescence and photocatalytic properties of three new metal–organic frameworks based on non-rigid long bridges

Three new metal–organic coordination polymers, [Cd3(5-NO2-bdc)2(5-NO2-bdcH)2(bpyo)2]n (1), [Mn(5-NO2-bdc)(bbim)]n (2) and {[Gd(5-NO2-bdc)(5-NO2-bdcH)](bpyo)0.5·2H2O}n (3) (5-NO2-bdcH2 = 5-nitro-1,3-benzenedicarboxylic acid; bpyo = 4,4′-bipyridine-N,N′-dioxide; bbim = 1,1′-(1,4-butanediyl)bis(benzimidazole)), were obtained under hydrothermal conditions and characterized structurally. The networks exhibit a variety of topologies and coordination modes at the metal centers. Complex 1 exhibits NaCl-type topology and contains the centrosymmetric trinuclear cluster SBU [Cd3(COO)4O2]. Complex 2 adopts CsCl-type topology based on bimetallic cores and is the first example of compounds containing a cis bbim bridge. Moreover, complex 3 possesses a 3D supramolecular framework by stronger contacts between 2D layers and non-rigid bpyo bridges. The thermal stabilities of 1–3, the photoluminescence properties of 1 as well as the photocatalytic performance of 3 were also examined, and the results indicated that 1 seems to be a good candidate for novel hybrid inorganic–organic photoactive materials, especially, compound 3 represents the rare example of coordination polymers with a 4f metal ion that exhibit good photocatalytic activity for dye degradation under UV light.

A series of metal–organic frameworks based on 5-(4-pyridyl)-isophthalic acid: selective sorption and fluorescence sensing

Solvothermal reactions of 5-(4-pyridyl)-isophthalic acid (H2pbdc) and transition-metal centers (Ni2+/Co2+/Zn2+) in the presence (or absence) of N-auxiliary 4,4′-bis(1-imidazolyl)biphenyl (bimb) ligand produce [Ni2(pbdc)2(μ2-H2O)(H2O)2·(DMA)2.7]n (DMA = N,N′-dimethylacetamide, 1), [Ni12(pbdc)12(μ2-H2O)6(py)2(H2O)8(DMA)2·(H2O)5·(DMA)9]n (2), [Co2(pbdc)2(bimb)2·(bimb)0.5·(H2O)4·(DMF)0.25]n (3) and [Zn(pbdc)(bimb)·(H2O)]n (4), which exhibit structural diversity. Both compounds 1 and 2 display a uninodal 8-connected 3D tsi net, but feature different crystal systems and space groups from each other. Compound 3 adopts a 2-fold interpenetrating binodal (3,5)-connected 3D hms net and compound 4 features a rare 2-fold interpenetrating binodal (3,4)-connected 3D fsx architecture. In particular, activated 3 shows high-efficiency for the selective sorption of small molecules, including CO2 over N2 and CH4, H2 over N2, as well as alcohols from water. More importantly, 4 represents the first report on a MOF as a promising luminescent probe for detecting pesticides, and also the very first example for detecting both pesticides and solvent molecules simultaneously.

A multifunctional cadmium–organic framework comprising tricarboxytriphenyl amine: selective gas adsorption, liquid-phase separation and luminescence sensing

The reaction of tricarboxytriphenyl amine (H3TCA) with CdII and auxiliary ligand 4,4′-bis(1-imidazolyl)biphenyl (bimb) afforded [Cd3(TCA)2(bimb)·(DMA)6]n (1) containing a two-fold interpenetrating three-dimensional microporous framework. Compound 1 showed remarkable adsorption enthalpies for CO2 and H2 and good H2/N2 selectivity at low temperature. Moreover, activated 1 showed a highly selective adsorption towards CO2 over N2 and CH4 under ambient conditions. Interestingly, compound 1 selectively removed methyl orange (MO) over methylene blue (MB) from contaminated water with good recyclability, and possessed the second highest adsorption capacity for MO among the MOFs reported to date. Remarkably, complex 1 showed strong guest-dependent luminescence behavior.

A highly stable multifunctional three-dimensional microporous framework: excellent selective sorption and visible photoluminescence

A Cd(II)-MOF [Cd(L)(DMF)] (1) (H2L = 5-(4-pyridyl)-isophthalic acid) featuring high thermal and chemical stability has been solvothermally synthesized and characterized. Complex 1 is a robust multifunctional three-dimensional (3D) microporous framework possessing an unusual (4,5)-connected topological net. Activated 1 shows high-efficiency for the selective capture of CO2 over N2 and CH4 under ambient conditions, which ranks it among MOFs with the highest selectivity. In addition, desolvated 1 exhibits good separation ratios of H2 over N2 at lower temperature, as well as alcohols from water. In particular, desolvated 1 demonstrates significantly higher adsorption enthalpies for CO2 and CH4 gas molecules, which are in the range of the highest Q(st) values reported to date. Furthermore, complex 1 displays visible photoluminescence in the solid state under UV irradiation.