Advancement in hydrogen storage techniques represents one of the most important areas of today's materials research. While extensive efforts have been made to the existing techniques, there is no viable storage technology capable of meeting the DOE cost and performance targets at the present time. New materials with significantly improved hydrogen adsorption capability are needed. Microporous metal coordination materials (MMOM) are promising candidates for use as sorbents in hydrogen adsorption. These materials possess physical characteristics similar to those of single-walled carbon nanotubes (SWNTs) but also exhibit a number of improved features. Here, we report a novel MMOM structure and its room-temperature hydrogen adsorption properties.

In an effort to make semiconductor nanomaterials with tunable properties, we have deliberately designed and synthesized a family of novel organic-inorganic hybrid nanocomposites based on II-VI semiconductors with structures ranging from one-dimensional (1-D) chain to two-dimensional layer (2-D) to three-dimensional (3-D) framework. All nanostructures exhibit strong quantum confinement effect (QCE), while possessing a perfectly periodic arrangement. The optical absorption experiments show that all compounds generate a very large blue shift in the absorption edge (1.0-2.0 eV) due to the strong QCE. More significantly, their band edge shift and optical properties can be tuned by changing the dimensionality of inorganic motifs as well as overall crystal structures. Raman studies reveal that not only do these structures have distinctly different vibrational signatures from those of the II-VI host semiconductors, but they also differ significantly from each other as a result of changes in dimensionality. The crystal structures of these nanocomposite materials have been characterized by single crystal and/or powder X-ray diffraction methods. [ZnTe(pda)] (1; pda = propanediamine) is composed of 1-D chains of [ZnTe] with pda chelating to Zn atoms. [ZnTe(N(2)H(4))] (2; N(2)H(4) = hydrazine) and [ZnTe(ma)] (3; ma = MeNH(2) = methylamine) are two-dimensional (2-D) layered structures containing [ZnTe] slabs and terminal hydrazine (2) or methylamine (3) molecules. The crystal structures of [CdSe(en)(0.5)] (4; en = ethylenediamine) and [CdSe(pda)(0.5)] (5) are 3-D networks containing [CdSe] slabs bridged by bidentate organic diamine molecules. Crystal data for 1: Orthorhombic, space group Pbcm, a = 9.997(2), b = 6.997(1), c = 10.332(2) A, Z = 4. For 2: Monoclinic, space group P2(1), a = 4.2222(6), b = 6.9057(9), c = 7.3031(10) A, beta = 98.92(8) degrees, Z = 2. For 3: Orthorhombic, Pbca, a = 7.179(1), b = 6.946(1), c = 18.913(4) A, Z = 8. For 4: Orthorhombic, Pbca, a = 7.0949(3), b = 6.795(3), c = 16.7212(8) A, Z = 8. For 5: Orthorhombic, Cmc2(1), a = 20.6660(12), b = 6.8900(4), c = 6.7513(4) A, Z = 8.

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In order to systematically tailor the structures and properties of a unique family of inorganic-organic hybrid nanostructured materials based on II-VI semiconductors, we have designed and engineered a new group of two-dimensional crystalline [(M2Q2)(L)] nanostreuctures (where M = Zn, Cd; Q = S, Se; and L = ethylamine, n-propylamine, n-butylamine, n-amylamine, n-hexylamine). These compounds are composed of double atomic layers of M2Q2 separated by organic monoamines. The crystal structures of 2D-[(M2Q2)(L)] are characterized by powder X-ray diffraction (PXRD) analysis. The crystal structures of these compounds are similar to the 2D-[(MQ)(L)] series that we reported earlier, in that they also contain II-VI slabs sandwiched by organic monoamines. The main difference is in the thickness of the II-VI slabs, where they are single-layer (n = 1) in 2D-[(MQ)(L)] but double-layer (n = 2) in 2D-[(M2Q2)(L)]. Optical absorption experiments show that all double-layer compounds exhibit a blue shift in their absorption edge (0.6-1.2 eV), due to the quantum confinement effect (QCE). However, the extent of such a blue shift is significantly less than that of the single-layer 2D-[(MQ)(L)] systems (1.0-2.0 eV) as a result of the difference in their layer thickness. Thermogravimetric (TG) analysis has revealed nanosized II-VI (MQ) particles as the post-TG product of all double-layer hybrids.

A novel guest-free metal organic framework (GFMMOF) is synthesized and structurally characterized. It contains one-dimensional close-packed open channels with a pore diameter of 4.5 A. It demonstrates a remarkable thermal stability, a unique ability to separate methanol from dimethyl ether or water, and is among the microporous MOFs having the highest adsorbed hydrogen density (0.054 g/cm3 at 77 K and 1 atm).

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Uranium is important in the nuclear fuel cycle both as an energy source and as radioactive waste. It is of vital importance to recover uranium from nuclear waste solutions for further treatment and disposal. Herein we present the first chalcogenide example, (Me2NH2)1.33(Me3NH)0.67Sn3S7·1.25H2O (FJSM-SnS), in which organic amine cations can be used for selective UO2(2+) ion-exchange. The UO2(2+)-exchange kinetics perfectly conforms to pseudo-second-order reaction, which is observed for the first time in a chalcogenide ion-exchanger. This reveals the chemical adsorption process and its ion-exchange mechanism. FJSM-SnS has excellent pH stability in both strongly acidic and basic environments (pH = 2.1-11), with a maximum uranium-exchange capacity of 338.43 mg/g. It can efficiently capture UO2(2+) ions in the presence of high concentrations of Na(+), Ca(2+), or HCO3(-) (the highest distribution coefficient Kd value reached 4.28 × 10(4) mL/g). The material is also very effective in removing of trace levels of U in the presence of excess Na(+) (the relative amounts of U removed are close to 100%). The UO2(2+)···S(2-) interactions are the basis for the high selectivity. Importantly, the uranyl ion in the exchanged products could be easily eluted with an environmentally friendly method, by treating the UO2(2+)-laden materials with a concentrated KCl solution. These advantages coupled with the very high loading capacity, low cost, environmentally friendly nature, and facile synthesis make FJSM-SnS a new promising remediation material for removal of radioactive U from nuclear waste solutions.

Two hybrid chloroantimonates(III), [Bzmim]3SbCl6 (1, Bzmim=1‐benzyl‐3‐methylimidazolium, Tm1=410 K) and [Bzmim]2SbCl5 (2, Tm2=348 K) are presented. 1 exhibits green emission (quantum efficiency of 87.5 %); 2 exhibits blue and red emissions under the irradiation of 310 and 396 nm light, respectively. Using different cooling methods, crystalline 1 and IL@2 (IL=ionic liquid of [Bzmim]Cl) could be generated from the molten 1. Reversible structural and PL transformation triggered by moisture or heat was observed between 1 and IL@2. Such PL switching, combined with the crystallization‐induced PL properties of 1 and 2, resulted in the firstly reported triple‐mode reversible PL switching, that is, on–off (T>Tm1), color switching (T