Unprecedented high fluorescence anisotropy in protic solvents: Hydrogen bond induced solvent caging?

Das, Sinjan; Ghosh, Saptarshi; Chattopadhyay, Nitin

doi:10.1016/j.cplett.2015.12.015

Cited by 18 publications

(37 citation statements)

References 18 publications

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“…However, increase in the viscosity of the medium or enhanced effective volume of the probe due to some specific interaction within the probe molecules (like formation of aggregates, as in the present case) or between the probe and the solvent might restrict the rotation process leading to an increase in its fluorescence anisotropy. 45,46…”

Section: Results and Discussionmentioning

confidence: 99%

Aggregation of Nile Red in Water: Prevention through Encapsulation in β-Cyclodextrin

2019

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The present work, based on various spectroscopic investigations, vividly demonstrates the self-association of Nile red (NR) in aqueous medium. The rapid decrease in the absorbance as well as emission of NR in water bears the signature of the aggregation process. Appearance of a new blue-shifted absorption band in addition to the original one and a drastic decrease in the emission intensity imply that the aggregation is of H-type. Poor solubility of NR in water, hydrophobic interaction, and the planar structure of the dye are ascribed to favor the formation of the aggregate in the aqueous medium. Absorption-based kinetic studies reveal the aggregation process to be second order, thereby establishing the aggregate to be a dimer. Similar kinetic profiles of the absorbance of NR in the presence and absence of light confirm that the aggregation process is not photoassisted. The presence of an isosbestic point in the absorbance spectra and an isoemissive point in the time-resolved area normalized emission spectra bears the evidence of equilibrium between the dimeric and the monomeric species of NR in the ground state as well as in the photoexcited state. Encapsulation of the monomer of NR within the hydrophobic cavity of β-cyclodextrin is demonstrated to prevent the aggregation process.

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Section: Results and Discussionmentioning

confidence: 99%

Aggregation of Nile Red in Water: Prevention through Encapsulation in β-Cyclodextrin

2019

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“…Only recently we have proposed, for the first time, that 3HF is not solvated in protic solvents in a symmetrical pattern. Rather, it forms a cage‐like structure with protic solvents through intermolecular hydrogen bonding which leads to unusually high fluorescence anisotropy in these solvents . Formation of this solvated structure of 3HF is further manifested by its breakdown with the addition of chaotropic agents (like guanidine hydrochloride or urea) and micelles resulting in the decrease of the fluorescence anisotropy relative to that in aqueous medium .…”

Section: Methodsmentioning

confidence: 99%

“…This implies that 3HF possesses the maximum effective size in water, which can be envisaged considering the intermolecularly hydrogen bonded probe‐solvent cage‐like network . Thus, the present work validates the inclusion assisted disruption of 3HF−water cage‐like structure in the presence of cyclodextrin, ascertaining formation of the 3HF−water clusters.…”

Section: Methodsmentioning

confidence: 99%

“…The hydrodynamic diameter of 3HF in water is measured to be ∼ 5.5 nm, consistent with our previous reports ,. The same for the encapsulated 3HFs came out to be ∼ 5.3, ∼ 4.8 and ∼ 3.3 nm in α‐, β‐ and γ‐CDs respectively (Figure ).…”

Section: Methodsmentioning

confidence: 99%

“…Since the fluorescence anisotropy of a probe provides a qualitative idea of its effective size in a specific environment,,, dynamic light scattering (DLS) measurements have been exploited for a quantitative measurement of the effective dimension of 3HF in different environments. It is pertinent to mention here that we have observed bimodal size distribution for α‐, β‐ and γ‐CDs treating the corresponding solutions even with 0.1 μm filter because of the equilibrium between the monomeric and the aggregated forms of the CDs in the solution, as reported by Wu et al …”

Section: Methodsmentioning

confidence: 99%

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Supramolecular Inclusion‐Assisted Disruption of Probe‐Solvent Network

Das

Chattopadhyay

2017

ChemistrySelect

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The present communication reports the disruption of probe‐solvent cluster formed by an excited state intramolecular proton transfer (ESIPT) prone molecular system and solvent water molecules because of the confinement of the probe within the cyclodextrin nano‐cavity. The disruption results in a decrease in the fluorescence anisotropy of the probe compared to its value in the aqueous medium. This is absolutely contrasting to the normal increasing trend for the fluorescence anisotropies of other fluorophores in similar constrained environments. This work substantiates the formation of probe‐solvent cluster in protic solvent and establishes the commanding role of hydrogen bonding in the solvation of the ESIPT probes.

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Exploration of synthetic antioxidant flavonoid analogs as acetylcholinesterase inhibitors: an approach towards finding their quantitative structure–activity relationship

et al. 2019

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Unprecedented high fluorescence anisotropy in protic solvents: Hydrogen bond induced solvent caging?

Cited by 18 publications

References 18 publications

Aggregation of Nile Red in Water: Prevention through Encapsulation in β-Cyclodextrin

Aggregation of Nile Red in Water: Prevention through Encapsulation in β-Cyclodextrin

Supramolecular Inclusion‐Assisted Disruption of Probe‐Solvent Network

Exploration of synthetic antioxidant flavonoid analogs as acetylcholinesterase inhibitors: an approach towards finding their quantitative structure–activity relationship

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