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Singlet Oxygen in Microporous Silica Xerogel: Quantum Yield and Oxidation at the Gas–Solid Interface
Author(s) -
Cantau Christophe,
Pigot Thierry,
Manoj Narayanapillai,
Oliveros Esther,
Lacombe Sylvie
Publication year - 2007
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200700482
Subject(s) - singlet oxygen , chemistry , quantum yield , benzophenone , photochemistry , phosphorescence , sulfoxide , benzoic acid , oxygen , quenching (fluorescence) , microporous material , singlet state , organic chemistry , fluorescence , physics , quantum mechanics , nuclear physics , excited state
Abstract The quantum yields of singlet oxygen ( 1 O 2 ) production ( Φ Δ ) and 1 O 2 lifetimes ( τ Δ ) at the gas–solid interface in silica gel material are determined. Different photosensitizers (PS) are encapsulated in parallelepipedic xerogel monoliths (PS‐SG). PS were chosen according to their known photooxidation properties: 9,10‐dicyanoanthracene (DCA), 9,10‐anthraquinone (ANT), and a benzophenone derivative, 4‐benzoyl benzoic acid (4BB). These experiments are mainly based on time‐resolved 1 O 2 phosphorescence detection, and the obtained Φ Δ and τ Δ values are compared with those of a reference sensitizer for 1 O 2 production, 1H‐phenalen‐1‐one (PN), included in the same xerogel. The trend between their ability to oxidize organic pollutants in the gas phase and their efficiency for 1 O 2 production is investigated through photooxidation experiments of a test pollutant dimethylsulfide (DMS). The Φ Δ value is high for DCA‐SG relative to the PN reference, whereas it is slightly lower for 4BB‐SG and for ANT‐SG. Φ Δ is related to the production of sulfoxide and sulfone as the main oxidation products for DMS photosensitized oxidation. Additional mechanisms, leading to CS bond cleaveage, appear to mainly occur for the less efficient singlet oxygen sensitizers 4BB‐SG and ANT‐SG.