We report the photophysical properties of a synthetic asymmetric azine-based compound (17Z,18E)-4′-((E)-3-phenylallylidene)-1′-(dimethylamino)-1-((pyren-8-yl)methylene)hydrazine (PYNC). The molecule PYNC shows an appreciable red shift in the emission maximum in a wide range of solvents. In water, PYNC shows the characteristic feature of excimer formation exclusively. However, in all other solvents, the excimer band is present alongside the charge transfer emission band. The assignment of charge transfer and excimer bands has been established by various steady-state emission spectral data. PYNC, owing to this novel excimer-coupled charge transfer phenomenon, can be a potential probe for studying various supramolecular assemblies of biological interest. © 2019 American Chemical Society.

NIKHIL GUCHHAIT

Chemistry

A BHATTACHARYYA

S C MAKHAL

Fulltext

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

ACS Omega

Photophysical properties of a newly designed synthetic compound DYMDAP have been investigated in combination with computational calculations. DYMDAP shows a solvent dependent emissive behavior which in non-polar solvents shows two distinct peaks along with a shoulder but with increasing polarity as also proticity of the solvents the intensity of each band varies significantly. Along with the two bands, a new band is observed in polar protic solvent due to the proton transfer (PT) in the excited state of the compound. Only in polar protic solvents, intensity of the PT band increases significantly whereas in non-polar or polar aprotic medium intensity is sparse. By comparing the spectral observations of DYMDAP with two control compounds DYMP and DYMDAB the proton transfer process is assigned to be due to solvent mediated and the proton transfer process is enhanced by the presence of charge transfer moiety. © 2018 Elsevier B.V.

Journal of Photochemistry and Photobiology A: Chemistry

A spectroscopic exploration of the influence of charge donor group on ESIPT process and its consequences in a salicylimine

We present a detailed photophysical properties of a synthesized charge transfer (CT) molecule (2E, 4E)-ethyl 2-cyano-5-(4-(dimethylamino) phenyl) penta-2, 4-dienoate (ECDPPD) in bulk medium and its spectral modulation inside β-Cyclodextrin cavity. Enhancement of acceptor strength of 4-(dimethylamino) cinnamaldehyde by replacing the moderate acceptor in the form of a Formyl group by two acceptors known to display greater electron withdrawing ability along with extra conjugation which may be responsible for higher dipole moment both in ground as well as in excited state. The observed excited CT process and its solvent polarity dependent emissive properties is due to simply increasing the ‘end-to-end’ length between donor and acceptor along with introduction of two different acceptors in the same site. Low fluorescence quantum yield and shorter fluorescence lifetime is due to the operation of active non-radiative channels through flexible bonds supported by viscosity and temperature dependent spectral measurement. The molecule ECDPPD easily interacts with β-CD with the formation of inclusion complex with a definite stoichiometry where the photophysics are modulated and hence can be used as fluorescence microenvironment reporter for example to evaluate the polarity as well as the micro viscosity of various regions of protein and other bimolecular systems. © 2018 Elsevier B.V.

Influence of acceptor strength on photoinduced charge transfer process in a newly designed molecule in bulk solvent and in Î²-CD microenvironment

A pyrene containing chemosensor viz. 1 has been designed for the efficient and selective detection of Cu2+ and F- ions in dual sensing mode which do not interfere with each other. The chemosensing behavior of 1 towards Cu2+ was demonstrated through fluorescence, time resolved fluorescence spectroscopy, and visual fluorescence colour changes, and towards F- through naked-eye colour changes, absorption and 1H NMR titrations. The chemosensor 1 shows excellent selectivity towards Cu2+ through an excimer switch-off mechanism. Density Functional Theory (DFT) calculations were performed to show the structure and electronic properties of 1 and its copper complex [1-Cu2+]. The selectivity and sensitivity towards F- were explained in terms of H-bonding interactions between 1 and F-, then deprotonation of 1. The biological application of 1 has been evaluated in HEK 293 cells and it exhibits good membrane permeability for the detection of Cu2+. The sensor also shows appreciable sensitivity towards fluoride in toothpaste. © The Royal Society of Chemistry 2016.

Dalton Transactions

Dual mode selective chemosensor for copper and fluoride ions: A fluorometric, colorimetric and theoretical investigation

A simple azine linkage containing Schiff base p-N, N- diethylaminobenzaldazine (PDEAB) has been synthesized and its spectroscopic properties have been investigated using steady state absorption and fluorescence measurement. Both the absorption and emission studies indicate that the compound PDEAB forms intermolecular hydrogen bond with protic solvents. The formation of intermolecular hydrogen bond between PDEAB and protic solvents is further verified by Quantum chemical calculation using Density Functional Theory (DFT)(B3LYP/6-31++G(d, p)) and Natural Bond Orbital (NBO) analysis. The non-fluorescent nature (fluorescence off) of PDEAB in aprotic environment can be switched over to a fluorescent system (fluorescence on) in presence of protic solvents and hence this molecule can be used as highly sensitive fluorosensor for protic solvent in aprotic medium like ACN or DOX. © 2013 Elsevier B.V. All rights reserved.

Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

Spectral properties of a simple azine Schiff base and its sensing ability towards protic environment through hydrogen bonding Interaction

A donor-acceptor substituted aromatic system (E)-3-(4-Methylamino-phenyl)- acrylic acid methyl ester (MAPAME) has been synthesized, and its photophysical behavior obtained spectroscopically has been compared with the theoretical results. The observed dual fluorescence from MAPAME has been assigned to emission from locally excited and twisted intramolecular charge transfer states. The donor and acceptor angular dependency on the ground and excited states potential energy surfaces have been calculated both in vacuo and in acetonitrile solvent using time dependent density functional theory (TDDFT) and TDDFT polarized continuum model (TDDFT-PCM), respectively. Calculation predicts that a stabilized twisted excited state is responsible for red shifted charge transfer emission. © 2006 American Chemical Society.

Journal of Physical Chemistry A

Photoinduced intramolecular charge transfer reaction in (E)-3-(4-methylamino-phenyl)-acrylic acid methyl ester: A fluorescence study in combination with TDDFT calculation

Journal	Data powered by TypesetACS Omega
Publisher	Data powered by TypesetAmerican Chemical Society
ISSN	2470-1343
Open Access	No