Author:

Keywords:

cyclosilicate hydrate, Cyclosilicate hydrate, hydrogen bonds, cubic silicate octamer, hexamethyleneimine, microporous material, x-ray-diffraction, triethyl-(2-hydroxyethyl)ammonium silicate solutions, nuclear-magnetic-resonance, double-ring silicate, crystal-structure, clathrate hydrate, tetramethylammonium silicate, structural links, zeolite-type, constitution, Science & Technology, Physical Sciences, Technology, Chemistry, Applied, Chemistry, Physical, Nanoscience & Nanotechnology, Materials Science, Multidisciplinary, Chemistry, Science & Technology - Other Topics, Materials Science, Hydrogen bonds, Cubic silicate octamer, Hexamethyleneimine, Microporous material, X-RAY-DIFFRACTION, TRIETHYL-(2-HYDROXYETHYL)AMMONIUM SILICATE SOLUTIONS, NUCLEAR-MAGNETIC-RESONANCE, DOUBLE-RING SILICATE, CLATHRATE HYDRATE, CRYSTAL-STRUCTURE, TETRAMETHYLAMMONIUM SILICATE, STRUCTURAL LINKS, ZEOLITE-TYPE, CONSTITUTION, 03 Chemical Sciences, 09 Engineering, Materials, 34 Chemical sciences, 40 Engineering

Abstract:

A new cyclosilicate hydrate with composition (C6H14N)(4)center dot[Si8O16(OH)(4)]center dot 12H(2)O was crystallized and the structure determined by single-crystal X-ray diffraction. The structure, described by the tetragonal space group I4(1)/a, with unit cell dimensions of a = 39.2150(2) angstrom and c = 14.1553(2) angstrom, contains columns of hydrogen-bonded cubic octamer silicate anions. The space between silicate columns holds hydrogen-bonded water and protonated hexamethyleneimine molecules compensating the negative charge of the silicate. The crystal water can be removed resulting in a rearrangement of the columns into ortho-rhombic symmetry. Removal of the organic moiety causes amorphisation. Flash evacuation results in a new microporous material with pore volumes typical of a zeolite. (C) 2009 Elsevier Inc. All rights reserved.