Periodic mesoporous hydridosilica-synthesis of an "impossible" material and its thermal transformation into brightly photoluminescent periodic mesoporous nanocrystal silicon-silica composite
Henderson, E. J.
Lofgreen, J. E.
Brodersen, P. M.
Ozin, G. A.
Journal of the American Chemical Society
5094 - 5102
Item Usage Stats
MetadataShow full item record
There has always been a fascination with "impossible" compounds, ones that do not break any rules of chemical bonding or valence but whose structures are unstable and do not exist. This instability can usually be rationalized in terms of chemical or physical restrictions associated with valence electron shells, multiple bonding, oxidation states, catenation, and the inert pair effect. In the pursuit of these "impossible" materials, appropriate conditions have sometimes been found to overcome these instabilities and synthesize missing compounds, yet for others these tricks have yet to be uncovered and the materials remain elusive. In the scientifically and technologically important field of periodic mesoporous silicas (PMS), one such "impossible" material is periodic mesoporous hydridosilica (meso-HSiO1.5). It is the archetype of a completely interrupted silica open framework material: its pore walls are comprised of a three-connected three-dimensional network that should be so thermodynamically unstable that any mesopores present would immediately collapse upon removal of the mesopore template. In this study we show that meso-HSiO1.5 can be synthesized by template-directed self-assembly of HSi(OEt)3 under aqueous acid-catalyzed conditions and after template extraction remains stable to 300 °C. Above this temperature, bond redistribution reactions initiate a metamorphic transformation which eventually yields periodic mesoporous nanocrystalline silicon-silica, meso-ncSi/SiO2, a nanocomposite material in which brightly photoluminescent silicon nanocrystallites are embedded within a silica matrix throughout the mesostructure. The integration of the properties of silicon nanocrystallinity with silica mesoporosity provides a wealth of new opportunities for emerging nanotechnologies.
Published Version (Please cite this version)http://dx.doi.org/10.1021/ja111495x
Showing items related by title, author, creator and subject.
Fabrication of mesoporous metal chalcogenide nanoflake silica thin films and spongy mesoporous CdS and CdSe Türker, Y.; Karakaya, C.; Dag, Ö. (Wiley Online Library, 2012-02-16)Mesoporous silica metal oxide (ZnO and CdO) thin films have been used as metal ion precursors to produce the first examples of mesoporous silica metal sulfide (mesoSiO2@ZnS, meso-SiO2@CdS) or silica metal selenide ...
Molten Salt Assisted Self-Assembly (MASA) : synthesis of mesoporous silica-ZnO and mesoporous CdO thin films Karakaya, Cüneyt (Bilkent University, 2012)A series of mesostructured salt-silica-two surfactants (salt is [Zn(H2O)6](NO3)2, ZnX or [Cd(H2O)4](NO3)2, CdYand surfactants are cetyltrimethylammonium bromide (CTAB) and 10-lauryl ether, C12H25(OCH2CH2)10OH, C12EO10) ...
Molten salt assisted self assembly (MASA): synthesis of mesoporous metal titanate (CoTiO3, MnTiO3, and Li4Ti5O12) thin films and monoliths Avcı, C.; Aydın, A.; Tuna, Z.; Yavuz, Z.; Yamauchi, Y.; Suzuki, N.; Dag, Ö. (American Chemical Society, 2014)Mesoporous metal titanates are very important class of materials for clean energy applications, specifically transition metal titanates and lithium titanates. The molten salt assisted self-assembly (MASA) process offers ...