Structural Diversity in Ga/In-Hydroxamate Metal-Organic Materials.

Developing metal-organic materials (MOMs) with chemical robustness is a prerequisite to exploring their intriguing properties and applications. As part of a continuing effort to construct robust MOMs featuring chelated building units, here we introduce a "bent" thiophene-2,5-dihydroxamate ligand with multiple intrinsic conformations when it is used as a chelating linkage. This approach should further diversify the coordination chemistry in hydroxamate-based MOM structures without compromising the stability. In combination with Group 13 metals Ga/In to ensure homoleptic metal vertices, we report the successful crystallization of four MOMs with diverse structures and dimensionalities: SUM-81 as a 0D metal-organic polyhedron (MOP), SUM-82 as a 2D MOF with an fes topology, SUM-83 and SUM-84 as distinct 1D coordination polymers with shapes mimic stairs and mesh tubes, respectively. As these structures indeed contain the aforementioned different ligand conformations and combinations thereof, these results expand our understanding of the coordination chemistry of hydroxamates. To demonstrate the potential applicability of hydroxamate-chelated robust MOMs, the permanently porous SUM-81 MOP was successfully incorporated in a series of mixed matrix membranes for CO2/N2 separation, showing impressive performances.

Sacrificial-Hydroxamate-Enabled Sizable Crystallization of Scandium Carboxylate Metal-Organic Frameworks.

Starting from labile hydroxamic acid ligands that are strong chelators, here, we implemented a sacrificial modulating strategy to prepare a series of scandium carboxylate metal-organic frameworks. Overcoming conventional syntheses that use excessive carboxylate modulators, the present strategy greatly reduces the organics required and produces large single crystals of several Sc-MOFs for X-ray crystallography.

Si-doped graphene nanosheets as a metal-free catalyst for electrochemical detection of nitroaromatic explosives.

Si-doped graphene nanosheets (SiGNS) have been successfully constructed via high temperature annealing of graphene oxide and tetraethoxysilane mixture in a sealed glass ampoule. The Si atoms doped into graphene's carbon network mainly existed as C3-Si-O and C2-Si-O2 configurations. The as-prepared SiGNS exhibited excellent electrochemical detection ability to nitroaromatic compounds in 0.1 M phosphoric acid buffer solution (PBS, pH = 8.0) via an electrochemical catalytic process. Five nitroaromatic compounds, including nitrobenzene, 2-nitrotoluene, 4-nitrotoluene, 2, 4-dinitrotoluene and 2, 4, 6-trinitrotoluene, were taken as the analyte to demonstrate the electrochemical catalytic ability of SiGNS. Density functional theory (DFT) calculation was carried out to explore the electrochemical catalytic mechanism of SiGNS. A hydrogen bond mediated electrochemical catalytic mechanism was proposed. Both the excellent electrical conductivity and the rich surface hydroxyl groups enhanced the electrochemical detection ability of SiGNS to nitroaromatic compounds. Si atoms in SiGNS played a key role for the excellent electrochemical detection ability of SiGNS due to most of the surface hydroxyl groups anchored on the Si atoms.