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In situ synthesis of silica gels via a one-step sol-gel process at ambient pressure or in supercritical CO2 was investigated. The influence of compressed gas, ultrasound irradiation, and quaternary ammonium salt (choline chloride) on the gelation time was determined. The obtained samples were characterized by N2 adsorption/desorption measurements, scanning electron microscopy in combination with energy dispersive X-ray spectroscopy (SEM/EDX), and Fourier transform infrared-attenuated total reflection spectroscopy (FTIR-ATR). The retention capacity of the corresponding silica aerogels for Rhodamine B was evaluated as a model for organic water pollutants. The obtained results proved that scCO2 has a beneficial effect, leading to a reduction of the gelation time. The obtained aerogels exhibit a higher surface area and larger pore diameter as well as a well-defined cylindrical pore structure.

The five new thioantimonates(III) ( i prH) 2 [Sb 8 S 13 ] ( I ), (1,2-dapH) 2 [Sb 8 S 13 ] ( II ), (1,3-dapH 2 )[Sb 8 S 13 ] ( III ), (dienH 2 )[Sb 8 S 13 ]⋅1.5H 2 O ( IV ), and (C 6 H 9 N 2 )[Sb 8 S 13 ]⋅2.5H 2 O ( V ) were synthesised under solvothermal conditions ( i pr = iso-propylamine; 1,2-dap = 1,2-diaminopropane; 1,3-dap = 1,3-diaminopropane; dien = diethylentriamine; C 6 H 9 N 2 = 3-(aminoethyl)-pyridine). The structures of compounds I and II are topological very similar and a central motif is a Sb 10 S 10 ring. On both sides of this ring Sb 5 S 5 rings are condensed. These rings are connected via Sb 4 S 4 rings leading to the sequence Sb 10 S 10 –Sb 5 S 5 –Sb 4 S 4 –Sb 5 S 5 –Sb 10 Sb 10 in the [010] direction. Further interconnection into the two-dimensional [Sb 8 S 13 ] 2− anion produces a large central Sb 18 S 18 ring with dimensions of 11⋅11 A 11 ⋅ 11 A in both compounds. The two atoms thick layers are linear and stacked along the a axis generating large channels running along [010]. The layered anion of compound III is constructed by interconnection of the SbS 3 and SbS 4 units yielding Sb 19 S 19 , Sb 14 S 14 , Sb 13 S 13 , and Sb 8 S 8 rings. The linear layers are two atoms thick and are stacked perpendicular to [001] to form channels running along the same direction. The last two compounds IV and V show a similar network topology. The layered anion is constructed by SbS 3 trigonal pyramids and SbS 4 units. The layer contains a Sb 12 S 12 rings as the main structural motif. The corrugated layers extending in the (100) plane are two atoms thick and are stacked in a manner that large tunnels run along [100]. The total potential solvent areas are large and range from 20.7% for III to 35% for II .

Five new thioantimonates have been synthesized in the presence of organic amines under solvothermal conditions and their structures determined by single-crystal X-ray diffraction. All of the compounds are layered and contain antimony-sulphide anions of stoichiometry [Sb4S7](2-), but the structure of the anion formed is dependent on the amine used in synthesis. (H3N(CH2)(4)NH3)[Sb4S7] (1) contains [Sb4S7](2-) double chains directed along [010]. Weak interchain Sb-S interactions between neighbouring chains cause the double chains to pack into layers in the ab plane. In the [001] direction, the layers of double chains alternate with doubly protonated diaminobutane molecules to which the chains are hydrogen bonded. Compounds of general formula (TH)(2)[Sb4S7] (T= CH3(CH2)(2)NH2 (2), (CH3)(2)CHNH2 (3), CH3(CH2)(3)NH2 (4) and CH3(CH2)(4)NH2 (5)) adopt a more complex structure in which [Sb3S8](7-) units are linked by Sb-3(3-) pyramids to form chains, which in turn are bridged by sulphur atoms to create sheets containing large heterorings. Pairs of such sheets form double layers of four atoms thickness that are stacked along [001]. Protonated amine molecules are located between anionic antimony-sulphide layers to which they are hydrogen bonded. Thermal analysis reveals that the decomposition temperature of materials containing [Sb4S7](2-) anions is dependent both on the structure of the anion, the lowest decomposition temperature being that of the low-dimensional phase (1) and on the identity of the amine, the decomposition temperature decreasing with an increasing number of carbon atoms and decreasing density. (c) 2005 Elsevier Inc. All rights reserved.

The CO(2) uptake on nanoscale AlO(OH) hollow spheres (260 mg g(-1)) as a new material is comparable to that on many metal-organic frameworks although their specific surface area is much lower (530 m(2) g(¬1)versus 1500-6000 m(2) g(¬1)). Suited temperature-pressure cycles allow for reversible storage and separation of CO(2) while the CO(2) uptake is 4.3-times higher as compared to N(2).

In the structure of the title compound, {(C3H13N2)[Sb8S14]} n , SbS3 pyramids are joined to form an [Sb4S7] chain. Two adjacent chains are joined via an S2 bridge, yielding the final [Sb8S14]2− anion. The structure-directing organic cations are located in the plane of large rings composed of ten S and eight Sb atoms. If Sb—S bonds longer than 3.1 Å are considered, a three-dimensional network with two types of channels is observed.

In the structure of the title compound, (C3H12N2)[Sb10S16], the SbS3 pyramids are interconnected to form a one-dimensional [Sb6S10]2− chain anion which contains 24-membered Sb12S12 rings that are interconnected. The structure-directing cations are located above and below this ring. Accepting Sb—S distances up to 3.2 Å, a three-dimensional thioantimonate(III) network results.

The crystal structure of the title compound, (C2H10N2)(C2H9N2)2[Sn2S6], consists of discrete [Sn2S6]4− anions and mono- as well as diprotonated ethyl­enediamine mol­ecules. The anion and the monoprotonated cation occupy general positions, whereas the dications are located on centres of inversion. In the crystal structure, the anions and cations are connected via N—H⋯S and N—H⋯N hydrogen bonds.

Postsynthetic metal ion exchange in a benzotriazolate-based MFU-4l(arge) framework leads to a Co(II)-containing framework with open metal sites showing reversible gas-phase oxidation properties.

Crystal structures of two metal-organic frameworks (MFU-1 and MFU-2) are presented, both of which contain redox-active Co(II) centres coordinated by linear 1,4-bis[(3,5-dimethyl)pyrazol-4-yl] ligands. In contrast to many MOFs reported previously, these compounds show excellent stability against hydrolytic decomposition. Catalytic turnover is achieved in oxidation reactions by employing tert-butyl hydroperoxide and the solid catalysts are easily recovered from the reaction mixture. Whereas heterogeneous catalysis is unambiguously demonstrated for MFU-1, MFU-2 shows catalytic activity due to slow metal leaching, emphasising the need for a deeper understanding of structure-reactivity relationships in the future design of redox-active metal-organic frameworks. Mechanistic details for oxidation reactions employing tert-butyl hydroperoxide are studied by UV/Vis and IR spectroscopy and XRPD measurements. The catalytic process accompanying changes of redox states and structural changes were investigated by means of cobalt K-edge X-ray absorption spectroscopy. To probe the putative binding modes of molecular oxygen, the isosteric heats of adsorption of O(2) were determined and compared with models from DFT calculations. The stabilities of the frameworks in an oxygen atmosphere as a reactive gas were examined by temperature-programmed oxidation (TPO). Solution impregnation of MFU-1 with a co-catalyst (N-hydroxyphthalimide) led to NHPI@MFU-1, which oxidised a range of organic substrates under ambient conditions by employing molecular oxygen from air. The catalytic reaction involved a biomimetic reaction cascade based on free radicals. The concept of an entatic state of the cobalt centres is proposed and its relevance for sustained catalytic activity is briefly discussed.

The new inorganic-organic hybrid compound (dienH2)Cu2Sn2S6 (dien = diethylenetriamine) was synthesized under solvothermal conditions. It crystallizes in the tetragonal space group I4m2 with a = 7.8793(3) A, c = 24.9955(15) A, and V = 1551.80(13) A(3). The structure consists of anionic [Cu2Sn2S6](2-) layers extending in the (001) plane and protonated amine molecules as charge compensating ions sandwiched between the layers. The layered [Cu2Sn2S6](2-) anion is composed of a single layer of edge-sharing CuS4 tetrahedra which is joined above and below to straight chains constructed by corner-sharing SnS4 tetrahedra. The material is a semiconductor with an optical band gap of 1.51 eV. More interestingly, preliminary results demonstrate that the compound exhibits photoconductive properties with an increase of the conductivity by a factor of 3 when irradiated with UV light. Upon heating in an inert atmosphere the compound starts to decompose at about 256 degrees C.