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Polarity Control at Interfaces: Quantifying Pseudo-solvent Effects in Nano-confined Systems

TitlePolarity Control at Interfaces: Quantifying Pseudo-solvent Effects in Nano-confined Systems
Publication TypeJournal Article
Year of Publication2016
AuthorsSingappuli-Arachchige, D, Manzano, JS, Sherman, LM, Slowing, II
JournalChemphyschem
Volume17
Pagination2982-2986
Date Published10
Type of ArticleArticle
ISBN Number1439-4235
Accession NumberWOS:000386790100006
Keywordsaerobic alcohol oxidation, carbon materials, chemistry, confinement effects, fluorescence, functionalization, heterogeneous catalysts, mesoporous, mesoporous materials, model, molecular environments, nanoparticles, physics, pyrene, self-assembled monolayers, silicas, solvent effects, Surface functionalization
Abstract

Surface functionalization controls local environments and induces solvent-like effects at liquid-solid interfaces. We explored structure-property relationships between organic groups bound to pore surfaces of mesoporous silica nanoparticles and Stokes shifts of the adsorbed solvatochromic dye Prodan. Correlating shifts of the dye on the surfaces with its shifts in solvents resulted in a local polarity scale for functionalized pores. The scale was validated by studying the effects of pore polarity on quenching of Nile Red fluorescence and on the vibronic band structure of pyrene. Measurements were done in aqueous suspensions of porous particles, proving that the dielectric properties in the pores are different from the bulk solvent. The precise control of pore polarity was used to enhance the catalytic activity of TEMPO in the aerobic oxidation of furfuryl alcohol in water. An inverse relationship was found between pore polarity and activity of TEMPO in the pores, demonstrating that controlling the local polarity around an active site allows modulating the activity of nanoconfined catalysts.

DOI10.1002/cphc.201600740
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3D Catalysis

Short TitleChemPhysChem
Alternate JournalChemPhysChem