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(2,2 '-Bipyridyl)-3-3 '-diol in Nafion: Stabilization of Unusual Ground and Excited States

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Title (2,2 '-Bipyridyl)-3-3 '-diol in Nafion: Stabilization of Unusual Ground and Excited States
 
Creator IYER, ESS
DATTA, A
 
Subject DOUBLE-PROTON-TRANSFER
NORMALIZED EMISSION-SPECTROSCOPY
CYCLODEXTRINS
PROBE
2-(2'-PYRIDYL)BENZIMIDAZOLE
2,2'-BIPYRIDINE-3,3'-DIOL
2,2'-BIPYRIDYL-3,3'-DIOL
MEMBRANES
DYNAMICS
 
Description (2,2'-Bipyridyl)-3-3'-diol (BP(OH)(2)) undergoes excited state intramolecular double proton transfer (ESIDPT). The photophysics of this molecule has been investigated, in the highly acidic water channels inside nafion membrane. The dianionic enolate form of the dye, which is formed only in alkaline conditions in neat aqueous solutions, is found to be present in its excited state in native nafion membrane at low water content. This surprising phenomenon has been explained in the light of loss of protons from the fluorophore to the medium, due to increased electrostatic interactions with the pendant sulfonate groups of nafion, at the lower water content. This observation fortifies the model of microscopic interactions that we have proposed in recent past. Further, the ground state of the diketo form, observed only in neat aqueous solutions so far, is found to be present in Na+-exchanged membranes at lower levels of hydration. The steady-state spectral features of the dye is different in (CH3)(4)N+-exchanged membranes than that of Ne-exchanged membranes, unlike in our earlier studies with coumarin 102 and 2-(2'-pyridyl)benzimidazole, here we observed formation of an unusual ground state in Na+-exchanged membranes, while no such feature was observed in (CH3)4N+-exchanged membranes.
 
Publisher AMER CHEMICAL SOC
 
Date 2014-10-16T12:52:08Z
2014-10-16T12:52:08Z
2012
 
Type Article
 
Identifier JOURNAL OF PHYSICAL CHEMISTRY B, 116(17)5302-5307
http://dx.doi.org/10.1021/jp301034v
http://dspace.library.iitb.ac.in/jspui/handle/100/15594
 
Language en