Tuning the "Light Switch"

• Main Authors: CHIEN, DA-EN, 錢大恩
• Other Authors: CHANG, I-JY
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/10165976247830465090

碩士 === 國立臺灣師範大學 === 化學系 === 94 === Abstract Complex Ru(bpy)2dppz2+ (dppz: dipyrido[3,2-a:2’,3’-c]phenazin) is a well-known "light switch." After irradiation, it exhibits intense emission in nonaqueous solution, but no emission in aqueous solution. The lifetimes for Ru(bpy)2dppz2+, Ru(dcbpy)2dppz2+, Ru(Cl2bpy)2dppz2+, Ru(tmbpy)2dppz2+ and Ru(dmbpy) 2dppz2+ are 759, 1297, 777, 146 and 264 ns in organic solvent, and 38, 951, 777, 7 and 15 ns in 10% H2O solution, respectively. Complexes Ru(bpy)2dppz2+, Ru(dmbpy)2dppz2+ and Ru(tmbpy)2dppz2+ have similar behavior that the emission is almost completely quenched at 10% water added. The emission intensity of Ru(Cl2bpy)2dppz2+ decreases graduately with increasing water amount up to 50%. Complex Ru(dcbpy)2dppz2+ has lifetime of 80 ns in aqueous solution. Complexes with strong electron withdrawing substituents have longer lifetimes. The emission intensity of these complexes in DNA solution is comparible to the one in nonaqueous solution. Their lifetimes for Ru(bpy)2dppz2+, Ru(dcbpy)2dppz2+, Ru(Cl2bpy)2dppz2+, Ru(tmbpy)2dppz2+ and Ru(dmbpy) 2dppz2+ are 190, 558, 419, 122 and 216 ns in DNA solution. The transient absorption spectra of Ru(tmbpy)2dppz2+ and Ru(dmbpy)2dppz2+ show that the MLCT excited-state has an absorption near 580 nm, which is characteristic of reduced dppz absorption. This is the direct evidence of a dppz localized MLCT excited state.