Xiufen Yan

Pt-doped graphene oxide/MIL-101 nanocomposites exhibiting enhanced hydrogen uptake at ambient temperature

Nanocomposites of Pt-doped graphene oxide (GO) and a chromate–organic framework (MIL-101) were prepared through the in situ solvent-thermal method. The parent materials and all composites have been characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, and gas adsorption analysis. The results indicated that the incorporation of a Pt/GO component did not prevent the formation of MIL-101 units. However, the crystallinities, morphologies, and surface areas of the composites were affected obviously by the Pt/GO content. The significant enhancement by a factor of 1.57–2.69 of hydrogen storage capacities at ambient temperature and 10 bar for the composites can be attributed reasonably to the spillover mechanism in such a system, in which Pt nanoparticles act as the spillover source of hydrogen molecules, while GO and MIL-101 act as the primary and secondary receptors, respectively.

Modulation of the optical properties of D-π-A type azobenzene derivatives by changing the π-conjugated backbones: A theoretical study

The optical properties of two series of azobenzene derivatives were modulated by backbone modifications with the density functional theory (DFT) calculations. Compared to the short-chain molecule, the chromophore with an elongated π-bridge exhibits a greater extent of charge transfer during one-photon excitation and hence possesses a larger molecular first hyperpolarizability (β0). Meanwhile, an evident red-shift in the maximum absorption was observed after extension of the π-conjugated backbone. The tendency of the static β0 value derived from the two-state model is consistent with the result of the calculation at M06-2X/6–311++G(d,p) level by means of analytical derivative method. The dynamic perturbations were revealed to cause the obvious enhancement of the first hyperpolarizability. The more closer the foundational wavelength to two times the value of the maximum absorption in one-photon transition, the larger βRHS value is observed for the chromophore. The nonlinear optical (NLO) properties augment with the introduction of the THF solvents by comparing the gas-phase values. With increasing the length of conjugated bridge, the dynamic βRHS value increases more rapidly in THF solution than in vacuum.

The Temperature Effect on the Structural Features of Bidentate Ligand-Decorated Cyanide-Bridged MnII-MoV Compounds: The Temperature Effect on the Structural Features of Bidentate Ligand-Decorated Cyanide-Bridged MnII-MoV Compounds

The diffusion reaction of Mn ions, the bidentate ligand dabco and [Mo(CN)8] units at different temperatures produced 2D layer [Mn(dabco)Mo(CN)8]2·[Mn(H2O)6]·2H2O (1) and 3D network [Mn(dabco)]2[Mn(CH3OH)4][Mo(CN)8]2·2H2O (2). Structural analysis revealed that there were two independent Mn centers (Mn1 and Mn2) in the structure for each compound, which exhibited trigonal bipyramid and octahedral geometry, respectively. Notably, the coordination mode of the Mn2 unit between layers in both compounds was responsible for the resulting structural dimensionalities. The crystal growth process of final products was dominantly controlled by the kinetics. The isolation of both compounds provides an insight into the effect of crystallization temperatures on the formation and structural conversion of manganese octacyanometalates. ____________ * Prof. A. H. Yuan E-Mail: aihua.yuan@juest.edu.cn [a] School of Material Science and Engineering Jiangsu University of Science and Technology Zhenjiang 212003, P. R. China [b] School of Environmental and Chemical Engineering Jiangsu University of Science and Technology Zhenjiang 212003, P. R. China [c] School of Chemistry and Chemical Engineering Jiangsu University Zhenjiang 212013, P. R. China Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/zaac.201700xxx or from the author.

CCDC 929256: Experimental Crystal Structure Determination

Related Article: Ying Zhang, Jue Wang, Xiufen Yan, Xiaoqing Liu, Hu Zhou, Aihua Yuan|2014|Microporous and Mesoporous Materials|184|15|doi:10.1016/j.micromeso.2013.09.035