Photoeffects in thin-film molecular-level chromophore-quencher assemblies. 1. Physical characterization

• Published in: Journal of physical chemistry (1952) Vol. 93; no. 1; pp. 294 - 304
• Main Authors: Surridge, Nigel A, McClanahan, Stephen F, Hupp, Joseph T, Danielson, Earl, Gould, Sharon, Meyer, Thomas J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 1989
• Subjects: 400500 - Photochemistry; CHEMICAL REACTIONS; DATA; ELECTRON TRANSFER; ENERGY LEVELS; EXCITED STATES; EXPERIMENTAL DATA; INFORMATION; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MATERIALS; NUMERICAL DATA; ORGANIC CHLORINE COMPOUNDS; ORGANIC COMPOUNDS; ORGANIC HALOGEN COMPOUNDS; ORGANIC POLYMERS; ORGANIC SULFUR COMPOUNDS; PETROCHEMICALS; PETROLEUM PRODUCTS; PHOTOCHEMICAL REACTIONS; PLASTICS; POLYMERS; POLYOLEFINS; POLYSTYRENE; POLYVINYLS; SYNTHETIC MATERIALS
• ISSN: 0022-3654; 1541-5740
• DOI: 10.1021/j100338a060

Molecular-level chromophore-quencher assemblies have been prepared in precast chlorosulfonated polystyrene ((-CH{sub 2}CH(p-C{sub 6}H{sub 4}SO{sub 2}Cl)){sub x}-; PS-SO{sub 2}Cl) films by (1) exposing the intact film to solutions containing the chromophore ((bpy){sub 2}Ru(5-NH{sub 2}phen))(PF{sub 6}){sub 2} (bpy is 2,2{prime}-bipyridine; 5-NH{sub 2}phen is 5-amino-1,10-phenanthroline) which becomes chemically bond through sulfonamide bond formation, (2) partially hydrolyzing a portion of the remaining -SO{sub 2}Cl sites to -SO{sub 3}- sites and exposing the resulting films to acetonitrile solutions containing the electron-transfer quencher paraquat (PQ{sup 2+}) and the reductive scavenger triethanolamine (N(C{sub 2}H{sub 4}OH){sub 3}). The photophysical properties of the chromophore-based metal-to-ligand charge-transfer excited state have been investigated by lifetime and visible absorption and emission spectra. Although similar to related monomers, excited-state decay in the films is nonexponential. The dynamics of excited-state quenching by PQ{sup 2+} following pulsed laser excitation show that the chromophore occupies three different chemical sites within the films. At one site, which accounts for {approx}50% of the emitted light and appears to be located near ion channels created by hydrolysis, quenching is rapid, K{sub SV} {approx} 6.8 {times} 10{sup 4} M{sup {minus}1}. A second site exists that undergoes relatively slow quenching, K{sub SV} {approx} 3 {times} 10{sup 3} M{sup {minus}1}, and then only with added (NEt{sub 4})(ClO{sub 4}). A third site is present that is not quenched.