Photoinduced Electron-Transfer Processes Based on Novel Bipyridine-Ru(II) Complex: Properties of cis-[Ru(2,2'-bipyridine)2(5,6-bis(3-amidopyridine)-7-oxanorbornene)](PF
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- 作者：Simone D. Inglez ; Francisco C. A. Lima ; Albé ; rico B. F. Silva ; Andreza R. Simioni ; Antô ; nio C. Tedesco ; Juliana F. S. Daniel ; Benedito S. Lima-Neto ; Rose M. Carlos
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：July 9, 2007
- 年：2007
- 卷：46
- 期：14
- 页码：5744 - 5753
- 全文大小：298K
- 年卷期：v.46,no.14(July 9, 2007)
- ISSN：1520-510X
文摘
This paper presents the synthesis, MO calculations, and photochemical and photophysical properties of cis-[Ru(bpy)2(3Amdpy2oxaNBE)](PF6)2 (2), where bpy is 2,2'-bipyridine and 3Amdpy2oxaNBE is the novel 5,6-bis(3-amidopyridine)-7-oxanorbornene chelate-ligand (1). Complex 2 is considered in relation to the cis-[Ru(bpy)2(3Amnpy)2](PF6)2 (3) analogous complex, where 3Amnpy is 3-aminopyridine. Complexes 2 and 3 exhibit absorptionsnear 350 nm and in the 420-500 nm region attributable to a contribution from MLCT transitions (d
bpy andd L; L = 3Amdpy2oxaNBE or 3Amnpy). Whereas complex 3 is photochemically reactive, complex 2 showsluminescence either at 77 K or at room temperature in fluid solution. The emission of 2 assignable as an MLCT(Ru bpy) emission is characterized by a long lifetime at room temperature (650 ns in CH3CN and 509 ns inH2O). It is independent of 
da.gif" BORDER=0 >irr, but it is temperature dependent; i.e., it increases as the temperature is lowered.Considering the chelate ring of 1 contributes to the stability of the complex 2 under continuous light irradiation, thedifference in the primary photoprocesses of 3 (loss of 3Amnpy) and 2 (luminescence) may be caused by a loweringof the lowest excited state from 3 to 2. The surface crossing to the lowest MC state value of 987 cm-1 (similar tothat of [Ru(bpy)3]2+) will be prevented in the case of complex 2, and as a result, efficient 3Amdpy moiety losscannot occur. The electronic depopulation of the {Ru(bpy)2} unit and population of a bpy* orbital upon excitationare evident by comparing the photophysical properties with those of a [Ru(bpy)3]2+ related complex. Moreover, areduction of a bpy ligand in the MLCT excited state is indicated by time-resolved spectra that show features typicalof bpy
-. The photocatalytic property of 2 is spectroscopically demonstrated by oxidative quenching using eithermethylviologen2+ or [RuCl(NH3)5]+2 electron-acceptor ions.
bpy andd L; L = 3Amdpy2oxaNBE or 3Amnpy). Whereas complex 3 is photochemically reactive, complex 2 showsluminescence either at 77 K or at room temperature in fluid solution. The emission of 2 assignable as an MLCT(Ru bpy) emission is characterized by a long lifetime at room temperature (650 ns in CH3CN and 509 ns inH2O). It is independent of da.gif" BORDER=0 >irr, but it is temperature dependent; i.e., it increases as the temperature is lowered.Considering the chelate ring of 1 contributes to the stability of the complex 2 under continuous light irradiation, thedifference in the primary photoprocesses of 3 (loss of 3Amnpy) and 2 (luminescence) may be caused by a loweringof the lowest excited state from 3 to 2. The surface crossing to the lowest MC state value of 987 cm-1 (similar tothat of [Ru(bpy)3]2+) will be prevented in the case of complex 2, and as a result, efficient 3Amdpy moiety losscannot occur. The electronic depopulation of the {Ru(bpy)2} unit and population of a bpy* orbital upon excitationare evident by comparing the photophysical properties with those of a [Ru(bpy)3]2+ related complex. Moreover, areduction of a bpy ligand in the MLCT excited state is indicated by time-resolved spectra that show features typicalof bpy-. The photocatalytic property of 2 is spectroscopically demonstrated by oxidative quenching using eithermethylviologen2+ or [RuCl(NH3)5]+2 electron-acceptor ions.