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Titolo:
Transition metal complexes in aminated silicate xerogels with Ni and Co ions
Autore:
Klonkowski, AM; Widernik, T; Grobelna, B; Mozgawa, W; Jankowska-Frydel, A;
Indirizzi:
Univ Gdansk, Fac Chem, PL-80952 Gdansk, Poland Univ Gdansk Gdansk PolandPL-80952 sk, Fac Chem, PL-80952 Gdansk, Poland Acad Min & Met, Inst Mat Engn, PL-30059 Krakow, Poland Acad Min & Met Krakow Poland PL-30059 Mat Engn, PL-30059 Krakow, Poland Univ Gdansk, Inst Expt Phys, PL-80952 Gdansk, Poland Univ Gdansk Gdansk Poland PL-80952 st Expt Phys, PL-80952 Gdansk, Poland
Titolo Testata:
MICROPOROUS AND MESOPOROUS MATERIALS
fascicolo: 1-2, volume: 31, anno: 1999,
pagine: 175 - 186
SICI:
1387-1811(199910)31:1-2<175:TMCIAS>2.0.ZU;2-O
Fonte:
ISI
Lingua:
ENG
Soggetto:
SOL-GEL PROCESS; GLASSES; SPECTRA; SPECTROSCOPY; COPPER(II); RESONANCE; EVOLUTION; ALKOXIDE; IR;
Keywords:
aminated xerogel; catalyst precursors; coordination environment; metal complexes; sol-gel method;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
35
Recensione:
Indirizzi per estratti:
Indirizzo: Klonkowski, AM Univ Gdansk, Fac Chem, Ul Sobieskiego 18, PL-80952 Gdansk, Poland Univ Gdansk Ul Sobieskiego 18 Gdansk Poland PL-80952 oland
Citazione:
A.M. Klonkowski et al., "Transition metal complexes in aminated silicate xerogels with Ni and Co ions", MICROP M M, 31(1-2), 1999, pp. 175-186

Abstract

Two series (N and N-N) of aminated silicate xerogels complexed with Ni2+ and Co2+ ions have been synthesized by a two-step reaction procedure: coordination and sol-gel process. The N series consists of unidentate ligands H2N(CH2)(3)SiO3/2 and the N-N series of bidentate ligands H2N(CH2)(2)NH(CH2)(3)SiO3/2. The coordination environments of the transition metal ions in the xerogels were analysed by UV-Vis absorption, luminescence, IR absorption and EPR spectroscopies. Moreover. the spectral data are complemented with thermoanalytical methods such as differential thermal analysis (DTA), differential thermogravimetry (DTG) and thermogravimetry (TG). The UV-Vis absorption and EPR spectra show that Ni and Co ions are in the +2 valence state in both xerogel series studied. For the Ni2+-and Co2+-doped xerogels the positions of the vibration bands related to the potential ligand groups and molecules (OH and H2O) are shifted according to the Irving-Williams order. In the case of Co2+, the tendency to transit from a tetrahedral to an octahedralenvironment increases with water and/or OH group content in the xerogels. When the temperature is increased, amino groups in the coordination sphere dissociate first and only then do amino groups not involved in coordinationdissociate. The modified silicate xerogels can be considered as catalyst precursors. (C) 1999 Elsevier Science B.V. All rights reserved.

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Documento generato il 01/12/20 alle ore 10:09:09