微調發光分子開關
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Date
2006
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摘 要
Ru(bpy)2(dppz)2+錯合物為有名的 "可開關發光分子"。因為有dppz特殊的配位基，在非質子的有機溶劑中經照光後可以發出磷光，但是在質子溶劑中照光後卻會被 H+淬息而不會發出磷光。本實驗中合成了五個錯合物Ru(bpy)2dppz2+、 Ru(dcbpy)2dppz2+、 Ru(Cl2bpy)2dppz2+, Ru(tmbpy)2dppz2+和 Ru(dmbpy) 2dppz2+。在有機溶劑中它們各別的生命期為759、1297、777、146和264 ns。加了10％的水後它們的生命期分別為38、951、777、7和15 ns。較強拉電子基的 Cl和 COOH接在bpy上會和dppz競爭電子密度，以致當水存在時不會使磷光隨即消失，至於 Ru(dcbpy)2dppz2+甚至在水中都還有80 ns的生命期。
將此類錯合物加入DNA後會藉由 pi stacking嵌合於DNA的鹼基對中間，而遮蔽掉質子和 dppz上和氮反應的可能性，所以錯合物在照光後也可以發出磷光。五個錯合物Ru(bpy)2dppz2+, Ru(dcbpy)2dppz2+, Ru(Cl2bpy)2dppz2+, Ru(tmbpy)2dppz2+和 Ru(dmbpy) 2dppz2+在 20 個鹼基的的 DNA中的生命期分別是190、558、419、122、216 ns。雖然仍不如在非質子的有機溶劑中，但是生命期比在水中增加了許多。
由瞬間吸收光譜可知Ru(tmbpy)2dppz2+和 Ru(dmbpy)2dppz2+有一在580 nm的吸收。此吸收和還原的dppz的光譜是相似的，直接證實了MLCT的電子是直接傳給 dppz 。
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.
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.
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釕吡啶錯合物, Ru, light switch, dppz