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Please use this identifier to cite or link to this item: http://dspace.library.iitb.ac.in/jspui/handle/10054/4317

Title: Early events associated with the excited state proton transfer in 2-(2(')-pyridyl)benzimidazole
Authors: BURAI, TN
MUKHERJEE, TK
LAHIRI, P
PANDA, D
DATTA, A
Keywords: slow dynamics
selective enhancement
atom transfer
ground-state
solvent
water
2-(2'-pyridyl)benzimidazole
fluorescence
temperature
viscosity
Issue Date: 2009
Publisher: AMER INST PHYSICS
Citation: JOURNAL OF CHEMICAL PHYSICS, 131(3), -
Abstract: 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.
URI: http://dx.doi.org/10.1063/1.3177457
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4317
http://hdl.handle.net/10054/4317
ISSN: 0021-9606
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