Hexakis(adamantyltrimethyl-ammonium) cyclooctasilicate tetratetracontahydrate

The title compound, 6C13H24N+· H2Si8O206-·44H2O, belongs to the class of cyclo-silicate hydrates, which structurally can be positioned between the zeosils and the clathrate hydrates. [Si8O 18(OH)2] cubes carrying six negative charges are located on crystallographic inversion centres and are surrounded by six adamantyl-trimethyl-ammonium cations. © 2010 International Union of Crystallography

Small angle x-ray scattering on TPA-Silicalite-1 precursors in clear solutions: influence of silica source and cations.

The formation and growth of crystal nuclei of TPA-Silicalite-1 (aluminum free ZSM-5) from clear solns. using TEOS and silicic acid as silica sources were studied with small angle X-ray scattering (SAXS). Information was obtained on the size and shape of nanoscopic precursor particles of silicalite-1. The SAXS data can be interpreted assuming the presence of tablets of 4x2x1.3 nm up to 8x8x1.3 nm depending on the synthesis conditions. Starting solns. have been studied varying the silica source and the cations content (Sodium, Potassium and TPA). In each case well defined particle sizes are obsd. Although the nanoparticles differ in size, their shape is very similar and these data strengthen our hypothesis that TPA-Silicalite-1 formation is a nanoblock based aggregation mechanism rather than growth via monomer addn

Zeosil nanoslabs: building blocks in nPr(4)N(+)-mediated synthesis of MFI zeolite

Tetrapropylammonium (TPA)-containing precursors are the building blocks in the crystallization of silica. In the first steps slab-shaped silicalite nanoparticles are formed by ordered combination of the precursors (see picture). These nanoslabs have MFI-type zeolite framework topology and play a key role in TPA-ion-mediated zeolite crystallization from monomeric and polymeric silica sources

Chromate-mediated one-step quantitative transformation of PW 12 into P 2W 20 polyoxometalates

The addition of H 3PW 12O 40 to an aqueous solution of K 2CrO 4 led to the hydrolysis of [PW 12O 40] 3- with its quantitative conversion into K 13[KP 2W 20O 72]. K 13[KP 2W 20O 72] in these chromate-containing solutions was characterized by 183W and 31P NMR, EXAFS, SAXS, and EPR spectroscopy. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

NH 2-MIL-53(Al): A high-contrast reversible solid-state nonlinear optical switch

The metal-organic framework NH 2-MIL-53(Al) is the first solid-state material displaying nonlinear optical switching due to a conformational change upon breathing. A switching contrast of at least 38 was observed. This transition originates in the restrained linker mobility in the very narrow pore configuration. © 2012 American Chemical Society