Photophysical properties of methyl ester of 2,6-dimethyl-1-amino-4-benzoic acid (M26DMB) have been investigated using steady state absorption and emission spectroscopy and time-resolved emission spectroscopy. Interestingly, not only in polar solvents, the molecule M26DMB having a weak primary amino donor group shows broad red-shifted emission band even in non-polar environment which in all probability arises from closely spaced local and charge transfer (CT) states. Clear dual fluorescence in polar protic solvents comprises of less intense local emission band and strong red-shifted CT band. The position of the red-shifted emission band is dependent on both the polarity and the hydrogen-bonding ability of the solvent. © 2009 Elsevier B.V. All rights reserved.

NIKHIL GUCHHAIT

Chemistry

S GHOSH

A CHAKRABORTY

S KAR

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

Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

Photophysical properties of an anthracene derivative 9-methyl anthroate (9-MA) have been investigated using absorption and emission spectroscopy, in combination with quantum chemical calculations. Solvatochromic effects on the Stokes shifted emission band clearly demonstrate the highly polar character of the excited state, which is also supported by the enhancement of dipole moment of the molecule upon photoexcitation. The emission band has been found to be dependent on polarity and hydrogen-bonding ability of the solvents. Multiple linear regression analysis method has been utilized to rationalize the effect of hydrogen bonding interaction on the emissive state, which was further confirmed by the analysis of the non-radiative decay constants and urea induced H-bonding disruption study. The experimental results correlate well with theoretical predictions obtained via density functional theory (DFT). © 2013 Elsevier B.V. All rights reserved.

Solvent modulated photophysics of 9-methyl anthroate: Exploring the effect of polarity and hydrogen bonding on the emissive state

Steady state absorption, fluorescence and time resolved fluorescence spectroscopy have been used for studying the photoinduced intramolecular charge transfer reaction in (E)-3-(4-methylamino-phenyl)-acrylic acid ethyl ester (MAPAEE). The title molecule shows dual emission due to high energy local and a low energy charge transfer emission. Depending on the nature of solvent the red shifted emission band shows good correlation with the solvent polarity parameter, ET(30) parameter and hydrogen bonding parameter. Quantum chemicals calculations by density functional theory predict that a stabilized twisted intramolecular charge transfer excited state generated either by twisting of the donor group ({single bond}NHMe) or the acceptor (- = {single bond}COOEt) group is responsible for the red shifted charge transfer emission. The solvent polarity dependent red shifted emission from the excited charge transfer state of MAPAEE has been used as fluorosensor to study bovine serum albumin proteinous and sodium dodecyl sulphate micellar microenvironment. © 2008 Elsevier B.V. All rights reserved.

Journal of Molecular Structure

Dual emission from (E)-3-(4-methylamino-phenyl)-acrylic acid ethyl ester (MAPAEE) and its application as fluorescence probe for studying micellar and protein microenvironment

The excited state intramolecular charge transfer process of a synthesized donor-acceptor naphthalene chromophoric system methyl ester of N,N′-Dimethylaminonaphthyl-(acrylic)-acid (MDMANA) has been investigated spectroscopically in combination with quantum chemical calculation. Apart from the local emission the molecule shows a solvent polarity dependent low energy emission from the charge transfer excited state. In polar protic solvents ground state hydrogen bonded clusters of MDMANA are formed which also shows low energy emission. Structural calculation and potential energy surfaces along both the donor and acceptor twist coordinates by considering twisted intramolecular charge transfer (TICT) model at density functional theory (DFT) level predict that a stabilized twisting geometry is responsible for charge transfer emission. The solvent polarity effect on the emission spectra has been explored using time-dependent density functional theory-polarizable continum model (TDDFT-PCM) which correlates well with the experimental spectral data. © 2007 Elsevier B.V. All rights reserved.

Journal of Photochemistry and Photobiology A: Chemistry

Photoinduced intramolecular charge transfer in methyl ester of N,Nâ€²-Dimethylaminonaphthyl-(acrylic)-acid: Spectroscopic measurement and quantum chemical calculations

In this work, we have studied the twisted intramolecular charge transfer process in ethyl ester of N,N′-Dimethylaminonaphthyl-(acrylic)-acid (EDMANA) using absorption and emission spectroscopy. Single conformer of EDMANA present in the ground state gives rise to local and charge transfer emission in different solvents. Solvatochromic effect on the Stokes shifted emission band clearly indicates the charge transfer character of the emitting singlet excited state. Considering twisted intramolecular charge transfer model, the ground and excited state properties of EDMANA have been evaluated along the donor and acceptor twisting coordinates separately using density functional theory (DFT) and time dependent density functional theory (TDDFT), respectively, with B3LYP functional and 6-31G basis set. The effect of solvent on the spectral properties has been explored theoretically at the same level with time dependent density functional theory-polarized continuum model (TDDFT-PCM) and the theoretical results support the solvent polarity dependent Stokes shifted emission of EDMANA molecule. © 2007 Elsevier B.V. All rights reserved.

Chemical Physics

Spectroscopic study of excited state intramolecular charge transfer in ethyl ester of N,Nâ€²-Dimethylaminonaphthyl-(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

The photophysical behaviour of trans-methyl p-(dimethylamino) cinnamate (t-MDMAC) donor-acceptor system has been investigated by steady-state absorption and emission spectroscopy and quantum chemical calculations. The molecule t-MDMAC shows an emission from the locally excited state in non-polar solvents. In addition to weak local emission, a strong solvent dependent red shifted fluorescence in polar aprotic solvents is attributed to highly polar intramolecular charge transfer state. However, the formation of hydrogen-bonded clusters with polar protic solvents has been suggested from a linear correlation between the observed red shifted fluorescence band maxima with hydrogen bonding parameters (α). Calculations by ab initio and density functional theory show that the lone pair electron at nitrogen center is out of plane of the benzene ring in the global minimum ground state structure. In the gas phase, a potential energy surface along the twist coordinate at the donor (-NMe 2) and acceptor (-CH = CHCOOMe) sites shows stabilization of S 1 state and destabilization S2 and S0 states. A similar potential energy calculation along the twist coordinate in acetonitrile solvent using non-equilibrium polarized continuum model also shows more stabilization of S1 state relative to other states and supports solvent dependent red shifted emission properties. In all types of calculations it is found that the nitrogen lone pair is delocalized over the benzene ring in the global minimum ground state and is localized on the nitrogen centre at the 90° twisted configuration. The S1 energy state stabilization along the twist coordinate at the donor site and localized nitrogen lone pair at the perpendicular configuration support well the observed dual fluorescence in terms of proposed twisted intramolecular charge transfer (TICT) model. © 2005 Elsevier B.V. All rights reserved.

Photoinduced intramolecular charge transfer (ICT) reaction in trans-methyl p-(dimethylamino) cinnamate: A combined fluorescence measurement and quantum chemical calculations

Journal	Data powered by TypesetSpectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
Publisher	Data powered by TypesetPERGAMON-ELSEVIER SCIENCE LTD
ISSN	1386-1425
Open Access	No