Xianqiang Huang

Shaping of Metal–Organic Frameworks: From Fluid to Shaped Bodies and Robust Foams

The applications of metal-organic frameworks (MOFs) toward industrial separation, catalysis, sensing, and some sophisticated devices are drastically affected by their intrinsic fragility and poor processability. Unlike organic polymers, MOF crystals are insoluble in any solvents and are usually not thermoplastic, which means traditional solvent- or melting-based processing techniques are not applicable for MOFs. Herein, a continuous phase transformation processing strategy is proposed for fabricating and shaping MOFs into processable fluids, shaped bodies, and even MOF foams that are capable of reversible transformation among these states. Based on this strategy, a cup-shaped Cu-MOF composite and hierarchically porous MOF foam were developed for highly efficient catalytic C-H oxidation (conv. 76% and sele. 93% for cup-shaped Cu-MOF composite and conv. 92% and sele. 97% for porous foam) with ease of recycling and dramatically improved kinetics. Furthermore, various MOF-based foams with low densities (<0.1 g cm(-3)) and high MOF loadings (up to 80 wt %) were obtained via this protocol. Imparted with hierarchically porous structures and fully accessible MOFs uniformly distributed, these foams presented low energy penalty (pressure drop <20 Pa, at 500 mL min(-1)) and showed potential applications as efficient membrane reactors.

Three New Imidazole-Functionalized Hexanuclear Oxidovanadium Clusters with Exceptional Catalytic Oxidation Properties for Alcohols

Cluster cat: Three new imidazole-functionalized neutral hexanuclear vanadium clusters have been prepared, one of which shows exceptional catalytic activity in the selective aerobic oxidation of alcohols (see scheme). Furthermore, these new polyoxovanadium clusters can be readily recycled and reused with unchanged catalytic activity. A plausible catalytic cycle is also proposed.

Cation-Induced Synthesis of New Polyoxopalladates

Seven polyoxopalladate compounds, [Pd(15)(SeO(3))(10)(μ(3)-O)(10)](10-), with Na(+) (1) and K(+) (2) as counterions, and Na(6)[M(II){Pd(12)(SeO(3))(8)(μ(4)-O)(8)}]·nH(2)O (M = Co (3), Zn (4), Ni (5), Cu (6), Mn (7); n = 7-9), have been prepared and characterized by SXRD, FT-IR, UV-vis, EA, TGA, and ESI-MS. These compounds comprise two distinct cluster configurations, {Pd(15)} and {M(II)Pd(12)}, which reveals the possibility of obtaining desired noble metal clusters with a certain nuclearity by using different cations as potential structural directing or template agents in synthesis. All compounds showed apparent absorptions in the visible light region, while 3 and 7 were found to show paramagnetic behavior typical of mononuclear Co(II) and Mn(II) complexes with zero-field splitting.

Facile fabrication of magnetically recyclable metal–organic framework nanocomposites for highly efficient and selective catalytic oxidation of benzylic C–H bonds

HKUST-1@Fe3O4 chemically bonded core-shell nanoparticles have been prepared by growing HKUST-1 thin layers joined by carboxyl groups onto Fe3O4 nanospheres. These magnetic core-shell MOF nanostructures show exceptional catalytic activity for the oxidation of benzylic C-H bonds and they can be recovered by magnetic separation and reused without losing any activity.

A Tale of Copper Coordination Frameworks: Controlled Single-Crystal-to-Single-Crystal Transformations and Their Catalytic C-H Bond Activation Properties.

Metal-organic frameworks (MOFs), as a class of microporous materials with well-defined channels and rich functionalities, hold great promise for various applications. Yet the formation and crystallization processes of various MOFs with distinct topology, connectivity, and properties remain largely unclear, and the control of such processes is rather challenging. Starting from a 0D Cu coordination polyhedron, MOP-1, we successfully unfolded it to give a new 1D-MOF by a single-crystal-to-single-crystal (SCSC) transformation process at room temperature as confirmed by SXRD. We also monitored the continuous transformation states by FTIR and PXRD. Cu MOFs with 2D and 3D networks were also obtained from this 1D-MOF by SCSC transformations. Furthermore, Cu MOFs with 0D, 1D, and 3D networks, MOP-1, 1D-MOF, and HKUST-1, show unique performances in the kinetics of the C-H bond catalytic oxidation reaction.

A new synthetic approach to functionalize oxomolybdenum complexes

A new synthetic approach is developed and nine distinct organic functionalized oxomolybdenum complexes, 1–9, are synthesized and fully characterized. Specifically by altering the functional groups on imidazoles we succeeded in making a series of crystalline structures with unique underlying topologies and/or functionalities. These imidazole derivatives can act as ligands, structural directing agents, counter cations and simultaneously, solvents where the reactions and the crystallization occur.

Two chiral multinuclear palladium(II) complexes comprising alternately arranged isomerous hexanuclear clusters

Two new chiral hexanuclear palladium(II) complexes [Pd6(Cys)4(CysH)4][Pd6(CysH)8]Cl4·24H2O (1) and [Pd6(HCys)10](NO3)2·11H2O (2) are prepared through careful control of the reaction conditions. Both complexes comprise two alternately arranged isomerous hexanuclear Pd(II) clusters. As supported by ESI-MS spectra and CD analyses, the integrity of the structures can be maintained in aqueous solution and the chirality of L-Cys ligands can be preserved to the multinuclear Pd complexes.