Excited-State Proton Transfer of 2-(2‘-Pyridyl)benzimidazole in Microemulsions:  Selective Enhancement and Slow Dynamics in Aerosol OT Reverse Micelles with an Aqueous Core

Mukherjee, Tushar Kanti; Panda, Debashis; Datta, Anindya

doi:10.1021/jp052917w

Cited by 50 publications

(70 citation statements)

References 69 publications

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“…8 The inclusion of 2PBI in cyclodextrins hinders the solvent-mediated ESPT to some extent due to shielding of the fluorophore from water. 9 Systematic studies have been performed on the ESPT of 2PBI in micelles, 10 reverse micelles, 11 and nafion film. 12 These studies reveal that the ESPT can be brought about in microheterogeneous media which contain water as a proton donor along with a nonpolar compartment, separated by a negatively charged interface.…”

Section: Introductionmentioning

confidence: 99%

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

Burai

Mukherjee²,

Lahiri³

et al. 2009

The Journal of Chemical Physics

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2-͑2Ј-pyridyl͒benzimidazole ͑2PBI͒ undergoes excited state proton transfer ͑ESPT͒ 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 ‫ء‬ ͒. In addition to the subnanosecond lifetime reported earlier, C ‫ء‬ 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 ‫ء‬ ͒ 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 ‫ء‬ emission. This is likely to arise from a structural change or charge redistribution in C ‫ء‬ immediately after its creation and before the phototautomerization.

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Section: Introductionmentioning

confidence: 99%

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

Burai

Mukherjee²,

Lahiri³

et al. 2009

The Journal of Chemical Physics

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“…22 The fluorescence decays have been collected with the emission polarizer at a magic angle of 54.7°and have been fitted to single or multiexponential functions after deconvolution of the IRF, using an iterative deconvolution method using IBH DAS 6.0 software. [23][24][25] Nonradiative rates have been calculated from f and radiative lifetimes ͑ f ͒ using the formula…”

Section: Introductionmentioning

confidence: 99%

The role of the ring nitrogen and the amino group in the solvent dependence of the excited-state dynamics of 3-aminoquinoline

Panda

Datta²

2006

The Journal of Chemical Physics

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The nonradiative rate in 3-aminoquinoline is found to exhibit anomalous solvent dependence, being rather fast in nonpolar solvents and remarkably slower in more polar and especially, more protic ones. The cause of such behavior is investigated by studying the dependence of fluorescence spectral and temporal parameters on the solvent properties such as polarity and hydrogen bonding ability. Complementary quantum mechanical calculations have been performed and the picture that emerges from these studies is that of an excited state with a short radiative lifetime due to the flipping of the amino group. This state is selectively populated in nonpolar, nonhydrogen bonding solvents, but is destabilized with respect to the more polar intramolecular charge transfer ͑ICT͒ state in polar solvents and even more so in protic solvents and dimethylsulfoxide. The slower nonradiative rates in the ICT state is attributed to the more restricted motion of the amino group in this state. The role of hydrogen bonding of the amino group and the ring nitrogen in stabilization/destabilization of the ICT state and therefore on the nonradiative rate is also explored.

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“…Multiexponential fitting of the decay traces was performed by using IBH DAS 6.2 data-analysis software. [51,52] The structure of BP(OH) 2 was geometrically optimized at the 6-31G* level by employing the Becke three-parameter Lee-Yang-Parr (B3LYP) hybrid density functional theory with the Gaussian 09 [53] software package, which converged into a planar structure, as obtained by single-crystal X-ray analysis. [24] The resulting energy-minimized structure was used to perform the molecular-docking experiments of BP(OH) 2 to the HSA protein crystal structure (PDB ID: 1A2), by using the Autodock 4.2 software package.…”

Section: Methodsmentioning

confidence: 99%

Unusual Binding of a Potential Biomarker with Human Serum Albumin

Kaur

Datta

2013

Chemistry An Asian Journal

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This study investigates the specific binding of a potential biomarker, [2,2'-bipyridyl]-3,3'-diol (BP(OH)2), with human serum albumin (HSA). The binding of BP(OH)2 at the two primary drug-binding sites on HSA (Sudlow's sites I and II) is explored by a competitive-binding study and monitored by considering the green-light emission from its diketo tautomer. Warfarin is used as a marker for site I and dansyl-L-proline (DP) as a competitor for site II. Steady-state and time-resolved fluorescence measurements affirm that neither of Sudlow's sites is the binding locus of BP(OH)2. To gain an idea regarding the probable binding site of BP(OH)2, we perform molecular-docking studies, which reveal a close proximity of the probe to Trp-214 in subdomain IIA of HSA. Confirmation of this contention is achieved by studying the quenching of the fluorescence of Trp-214 in the presence of BP(OH)2. Moreover, static quenching seems to be responsible for the depletion of the fluorescence of Trp-214, as manifested by the invariance of the intrinsic fluorescence lifetime of Trp-214, as a function of the concentration of BP(OH)2. Based on displacement and quenching studies, supported by molecular docking, we propose that BP(OH)2 binds in a cleft that separates subdomains IIIA and IIB, which is in close proximity to Trp-214.

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Excited-State Proton Transfer of 2-(2‘-Pyridyl)benzimidazole in Microemulsions: Selective Enhancement and Slow Dynamics in Aerosol OT Reverse Micelles with an Aqueous Core

Cited by 50 publications

References 69 publications

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

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

The role of the ring nitrogen and the amino group in the solvent dependence of the excited-state dynamics of 3-aminoquinoline

Unusual Binding of a Potential Biomarker with Human Serum Albumin

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