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ESPT of 2-(2'-pyridyl)benzimidazole at the micelle-water interface: Selective enhancement and slow dynamics with sodium dodecyl sulfate

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Title ESPT of 2-(2'-pyridyl)benzimidazole at the micelle-water interface: Selective enhancement and slow dynamics with sodium dodecyl sulfate
 
Creator MUKHERJEE, TK
AHUJA, P
KONER, AL
DATTA, A
 
Subject excited-state proton
h-atom transfer
normalized emission-spectroscopy
perylene quinones
7-azaindole dimer
aqueous-solution
fluorescence-spectra
reversed micelles
hydrogen-bond
base-pair
 
Description The effect of micellar environment on the excited state proton transfer (ESPT) of 2-(2'-pyridyl)benzimidazole (2PBI) has been investigated by steady state and time resolved fluorescence spectroscopy. The ESPT, which occurs to a rather small extent at pH 7, is found to be enhanced remarkably at the interface of sodium dodecyl sulfate (SDS) micelles and water. Such an enhancement is not observed for the cationic cetyl trimethyl ammonium bromide (CTAB) or neutral Triton X-100 micelles. This selective enhancement is explained in the light of a modification of pK(a) and a more acidic local pH in the micelle-water interface. A rise time of about 890 ps is observed in the region of tautomer emission. The origin of this rise time is explored, considering three factors, namely, diffusion controlled protonation of the normal form of 2PBI, slow and possibly incomplete solvation of the transition state, leading to a slowing down of the proton transfer process and a similar slow dynamics of the tautomeric excited state.
 
Publisher AMER CHEMICAL SOC
 
Date 2011-07-14T02:14:00Z
2011-12-26T12:47:30Z
2011-12-27T05:35:27Z
2011-07-14T02:14:00Z
2011-12-26T12:47:30Z
2011-12-27T05:35:27Z
2005
 
Type Article
 
Identifier JOURNAL OF PHYSICAL CHEMISTRY B, 109(25), 12567-12573
1520-6106
http://dx.doi.org/10.1021/jp051574z
http://dspace.library.iitb.ac.in/xmlui/handle/10054/3832
http://hdl.handle.net/10054/3832
 
Language en