The absorption and emission characteristics of donor-acceptor charge transfer system 4-amino-3-methyl benzoic acid methyl ester (AMBME), capable of dual emission, i.e., local emission (LE) and charge transfer (CT) emission, have been investigated inside the β-cyclodextrin (β-CD) nanocavity in the aqueous and non-aqueous dimethylsulphoxide (DMSO) medium. Large enhancement of both LE and CT band in aqueous β-CD medium is due to decrease in non-radiative processes in less polar and restricted environment. Whereas in non-aqueous DMSO medium the CT process is hindered as a result CT intensity decreases with enhancement of LE band. These spectral differences indicate that in aqueous medium the donor -NH2 group sticking in the hydrophilic region of β-CD cavity whereas in non-aqueous DMSO medium it exists in the hydrophobic part of the cavity. Spectral characteristics indicate that different stoichiometry of host-guest inclusion complexes are formed in aqueous and non-aqueous β-CD medium.

NIKHIL GUCHHAIT

Chemistry

A CHAKRABORTY

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Journal of Inclusion Phenomena and Macrocyclic Chemistry

This article reports modulation of intramolecular charge transfer (ICT) reaction of 2-methoxy-4-(N,N-dimethylamino)benzaldehyde (2-MDMABA) encapsulated within the cyclodextrin nanocavities investigated by steady state and time resolved measurements. The ICT emission, absent in bulk water, originates in the presence of α-, β- and γ-CD with the huge enhancement of local emission. From the Benesi-Hildebrand plot, the stoichiometry of the host-guest inclusion complex is found to be 1:1 for β- and γ-CD whereas 1:1 and 1:2 guest to host complexation occur at low and high concentration of α-CD, respectively. The association constants of the inclusion complexes have also been estimated from the Benesi-Hildebrand plot. The greater binding capability of 2-MDMABA with β-CD than that of other two CDs is further supplemented by time resolved study. © 2012 Springer Science+Business Media B.V.

Spectral modulation of a charge transfer reaction of 2-methoxy-4-(N,N- dimethylamino)benzaldehyde inside cyclodextrin nanocage

The present work demonstrates the interaction of an intramolecular charge transfer (ICT) probe 5-(4-dimethylamino-phenyl)-penta-2,4-dienoic acid methyl ester (DPDAME) with liposome membranes of dimyristoyl-l-α-phosphatidylcholine (DMPC) and dimyristoyl-l-α-phosphatidylglycerol (DMPG) studied by steady-state absorption, emission and time-resolved emission techniques. A huge hypsochromic shift together with remarkable enhancement of fluorescence quantum yield of the polarity sensitive ICT emission of DPDAME upon interaction with the lipids has been rationalized in terms of incorporation of the probe into hydrophobic interior of the lipids. Compelling evidences for penetration of the probe into the hydrocarbon interior of the lipids have been deduced from intertwining different experimental results e.g., micropolarity in the immediate vicinity of the probe in lipid environments, steady-state anisotropy, red-edge excitation shift (REES), fluorescence quenching experiments and time-resolved measurements. The rotational relaxation dynamics study of the membrane-bound probe unveils the impartation of high degree of motional rigidity. Wavelength-selective emission behaviour paves way for monitoring of solvent-relaxation in the membranes. Overall, the ICT probe DPDAME displays its commendable sensitivity in deciphering the microheterogeneous environments of liposomal membranes of DMPC and DMPG and promises a new membrane-polarity sensitizing probe. © 2011 Elsevier Inc.

Journal of Colloid and Interface Science

Spectroscopic probing of location and dynamics of an environment-sensitive intramolecular charge transfer probe within liposome membranes

Changes in polarity at the immediate binding site in protein bovine serum albumin (BSA) produces distinct changes in the solvent polarity-dependent emission band of fluorescence probe E-3-(4-dimethylamino-naphthalen-1-yl)- acrylic acid. Steady-state spectroscopy and time-resolved spectroscopy have been used to investigate this binding process. Attaching the probe to BSA and then monitoring its spectral changes with increasing urea concentration and raising temperature has also tracked the denaturation of BSA chemically and thermally. The polarity of the microenvironment was investigated employing the Reichardt E T (30) scale. Fluorescence anisotropy, red edge excitation shifts and acrylamide-induced quenching of fluorescence have been exploited to gain better insight into this binding process. © 2009 The American Society of Photobiology.

Photochemistry and Photobiology

Fluorescent probing of urea-induced chemical unfolding of bovine serum albumin by intramolecular charge transfer fluorescence probe E-3-(4-Dimethylamino-Naphthalen-1-yl)-acrylic acid

Photoinduced intramolecular charge-transfer reactions in 4-amino-3-methyl benzoic acid methyl ester (AMBME) have been investigated spectroscopically. AMBME, with its weak charge donor primary amino group, shows dual emission in polar solvents. Absorption and emission measurements in the condensed phase support the premise that the short wavelength emission band corresponds to local emission and the long wavelength emission band to the charge transfer emission. Laser-induced fluorescence excitation spectra show the presence of two low-energy conformers in jet-cooled molecular beams. Theoretical calculations using density functional theory help to determine structure, vibrational modes, potential energy surface, transition energy and oscillator strength for correlating experimental findings with theoretical results. © Indian Academy of Sciences.

Fulltext

Journal of Chemical Sciences

Photoinduced intramolecular charge-transfer reactions in 4-amino-3-methyl benzoic acid methyl ester: A fluorescence study in condensed-phase and jet-cooled molecular beams

Spectral properties and supramolecular inclusion complex formation between 2-styrylbenzothiazolium dye and cyclodextrins

Spectrofluorometric, thermal, and molecular mechanics studies of the inclusion complexation of selected imidazoline-derived drugs with β-cyclodextrin in aqueous media

Effects of cyclodextrins and saccharides on dual fluorescence of N,N-dimethyl-4-aminophenylboronic acid in water

Journal of Physical Organic Chemistry

Host–guest complexes of phenol derivatives with β-cyclodextrin: an experimental and theoretical investigation

Inclusion complex of charge transfer probe 4-amino-3-methyl benzoic acid methyl ester (AMBME) with Î²-CD in aqueous and non-aqueous medium: Medium dependent stoichiometry of the complex and orientation of probe molecule inside Î²-CD nanocavity

Journal	Journal of Inclusion Phenomena and Macrocyclic Chemistry
Publisher	-
ISSN	0923-0750
Open Access	No