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Early events associated with the excited state proton transfer in 2-(2(')-pyridyl)benzimidazole

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Title Early events associated with the excited state proton transfer in 2-(2(')-pyridyl)benzimidazole
 
Creator BURAI, TN
MUKHERJEE, TK
LAHIRI, P
PANDA, D
DATTA, A
 
Subject slow dynamics
selective enhancement
atom transfer
ground-state
solvent
water
2-(2'-pyridyl)benzimidazole
fluorescence
temperature
viscosity
association
chemical exchanges
excited states
fluorescence
ground states
liquid mixtures
organic compounds
photochemistry
viscosity
 
Description 2-(2(')-pyridyl)benzimidazole (2PBI) undergoes excited state proton transfer (ESPT) in acidic solutions, leading to a tautomer emission at 460 nm. This photoprocess has been studied using ultrafast fluorescence spectroscopic techniques in acidic neat aqueous solutions, in viscous mixtures of glycerol with water, as well as in sucrose solutions. The tautomer is found to be stabilized in the more viscous medium, leading to a greater relative quantum yield as well as lifetime. The long rise time in tautomer emission is not affected by viscosity though. Rather, it appears to have the same value as the long component of the decay of the cationic excited state (C(*)). In addition to the subnanosecond lifetime reported earlier, C(*) is found to exhibit a decay time of 2 ps. This is assigned to its protonation to form the nonfluorescent dication in its excited state (D(*)) considering the ground and excited state pK(a) values reported earlier. An additional rising component of 100 ps is observed in the region of C(*) emission. This is likely to arise from a structural change or charge redistribution in C(*) immediately after its creation and before the phototautomerization.
 
Publisher AMER INST PHYSICS
 
Date 2011-07-15T15:32:22Z
2011-12-26T12:49:34Z
2011-12-27T05:34:44Z
2011-07-15T15:32:22Z
2011-12-26T12:49:34Z
2011-12-27T05:34:44Z
2009
 
Type Article
 
Identifier JOURNAL OF CHEMICAL PHYSICS, 131(3), -
0021-9606
http://dx.doi.org/10.1063/1.3177457
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4317
http://hdl.handle.net/10054/4317
 
Language en