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Organozinc‐ and Imidazole‐Modified Periodic Mesoporous Organosilicas by Means of Molecular Grafting
Author(s) -
Liang Yucang,
Erichsen Egil Severin,
Song Chen,
Anwander Reiner
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201200820
Subject(s) - silanol , chemistry , triethoxysilane , mesoporous organosilica , imidazole , mcm 41 , mesoporous material , polymer chemistry , siloxane , diethylzinc , nuclear chemistry , inorganic chemistry , mesoporous silica , organic chemistry , catalysis , enantioselective synthesis , polymer
Cagelike cubic periodic mesoporous organosilicas PMO[SBA‐1] with various pore diameters and distorted hexagonal PMO[MCM‐41] as supports were synthesized by using 1,2‐bis(triethoxysilyl)ethane as an organosilica source, and a mixture of binary surfactants C 18‐3‐1 and C 18 TABr as a template under basic conditions. Surface silanol group populations (0.72–1.41 mmol g –1 ) of PMO[SBA‐1] and PMO[MCM‐41] were determined by carbon elemental analysis from surface silylation. Diethylzinc was immobilized on PMOs to afford ZnEt x @PMO[SBA‐1]/[MCM‐41] with various Zn loading (1.60–2.38 mmol g –1 ), which depended on surface silanol population of the corresponding PMOs and the number of cleaved siloxane bonds. The surface ethyl groups coordinated to zinc can be exchanged readily by the 4‐methyl‐2,6‐dibutylphenoxy or di‐ tert ‐butylsilanoxy group to give various organozinc‐modified PMO materials ZnR x @PMO[SBA‐1]/[MCM‐41] (herein, R represents 4‐methyl‐2,6‐dibutylphenoxy and di‐ tert ‐butylsilanoxy groups). Moreover, N ‐(3‐triethoxysilylpropyl)‐4,5‐dihydroimidazole was grafted onto the PMO surfaces to afford hybrid materials Si(OEt) y (CH 2 ) 3 (imidazole)@PMO[SBA‐1]/[MCM‐41] with the amount of functional groups ranging from 0.36 to 0.70 mmol g –1 . The coordination behavior of the surface functional groups with diethylzinc was investigated, and possible coordination modes were hypothesized. All materials were characterized by infrared spectroscopy, N 2 physisorption, and elemental analysis. Representative 1 H and 13 C NMR spectra of a selected organozinc‐/imidazole‐functionalized PMO were recorded to corroborate the proposed surface species. This work presents a versatile approach to the fabrication of multiple surface species that coexist on a support for exploiting the potential application of novel heterogeneous catalysts.