Synthesis and modification of titanosilicate ets-10: its role as host in host-guest systems

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2014
İşler, Melda
An attractive method to create new molecular level electronic, optical and magnetic devices is to use solid host lattices that serve as templates within which a guest structure of nanometer architecture can be assembled. Zeolites and zeo-type materials with nanopores and cavities in 3-dimensions are known to represent a “New Frontier” of solid state chemistry with great opportunities for innovative research. Titanosilicate ETS-10, a microporous material, possessing two perpendicular channels, is an alternative, promising zeo-type material for host-guest systems with its most intriguing property of possessing two dimensional Ti-O-Ti quantum wires with semiconductor properties. Furthermore, it is critical to control concentration and type of defects inside zeolite crystals in order to enhance diffusion access through three dimensional pore systems for host-guest systems. An approach to form defects; i.e. intracrystalline mesoporosity, can be obtained by post-synthesis modification. In the current study, the aim was to investigate synthesis of ETS-10 crystals possessing several morphologies and host-guest systems in which ETS-10 was used as a host material and ruthenium nanoparticles as well as dye molecules as guest materials. ETS-10 crystals were synthesized with various molar compositions in order to achieve ETS-10 crystals with desired morphology. Some of the ETS-10 nanocrystals were modified by post-synthesis methods; i.e. consecutive hydrogen peroxide and sulfuric acid treatments. Secondly, ETS-10 crystals that were subjected to the above mentioned post-synthesis modifications and those that were not modified were investigated as host material by incorporating nanoparticles or dye molecules. For the investigation of ETS-10 as a host material for metallic nanoparticles, ruthenium nanoparticles were aimed to be incorporated into both as-synthesized and post-treated ETS-10 crystals. The resulting ETS-10 crystals were characterized by XRD, FE-SEM, ICP-MS, HR-TEM and N2 adsorption/desorption methods in order to comprehend the effect of defects formed by post-treatments in ruthenium nanoparticle formation in ETS-10 matrix. As an alternative to metallic nanoparticle formation, ship-in-a-bottle synthesis of a ruthenium based dye molecule, that is of high demand in photovoltaic studies was sought to be formed in the ETS-10 matrix. For this purpose, tris(2,2’-bipyridiyl)ruthenium(II) cation, an organometallic dye molecule, was incorporated with the ETS-10 matrix for the first time. The characterization of tris(2,2’-bipyridiyl)ruthenium(II) cation incorporated into ETS-10 was performed by FT-IR, UV-Vis spectroscopy and CLSM. Furthermore, pyronine as a small linear molecule was loaded into ETS-10 and characterized by CLSM in order to observe the diffusion of a small cationic dye into ETS-10 as an alternative.
Citation Formats
M. İşler, “Synthesis and modification of titanosilicate ets-10: its role as host in host-guest systems,” M.S. - Master of Science, Middle East Technical University, 2014.