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How are Heteroelements (Ga and Ge) Incorporated in Silicate Oligomers?
Author(s) -
Schaack Bernd Bastian,
Schrader Wolfgang,
Schüth Ferdi
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200900472
Subject(s) - microporous material , silicate , silicon , gallium , electrospray ionization , aqueous solution , germanium , chemistry , mass spectrometry , hydrolysis , zeolite , ionization , crystallography , chromatography , organic chemistry , ion , catalysis
Uncovering the mystery : Typical zeolite prenucleating solutions containing Ga and Ge were studied by ESI‐MS. Ga and Ge incorporate into the oligomers in different ways, and their structure‐directing effect appears stronger than that of the template. MS/MS experiments were used to obtain detailed structural information about the occurring species (see figure).The properties of microporous solids can be strongly influenced during the first stages of solid‐state formation from solution. Furthermore, their properties are directly related to the presence, number, and character of intra‐ or extraframework heteroelements. In this contribution we studied the influence of the substitution of silicon against heteroelements, such as gallium and germanium. The aqueous prenucleating solutions were obtained by hydrolysis of the silicon and heteroelement sources in the presence of tetraalkylammonium cations. The time‐resolved stepwise formation of larger oligomers was studied by using electrospray ionization mass spectrometry (ESI‐MS). Furthermore, the structures of the obtained signals were verified by using MS/MS experiments, which led to the conclusion that strong structure‐directing effects emerge from the introduction of heteroelements into the solutions.