Photoinduced intramolecular charge transfer in methyl ester of N,N′-Dimethylaminonaphthyl-(acrylic)-acid: Spectroscopic measurement and quantum chemical calculations (original) (raw)
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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
Description of synthetic procedures 6-Dimethylamino-3H-isobenzofuran-1-one (6-DMAPd, referred to in this work as 6dimethylaminophthalide) was prepared quantitatively from 6-nitro-3H-isobenzofuran-1-one by simultaneous hydrogenation and reductive methylation over 10% Pd/C catalyst in the presence of 35% aqueous formaldehyde while maintaining conditions similar to those reported by Stanetty et al. 1 , except the reaction was carried out under normal pressure of hydrogen. White crystals from n-hexane, m. p.: 122° C, (lit. 121-122° C) 1 .
Journal of Photochemistry and Photobiology A: Chemistry, 2010
The photophysical behavior of 2-methoxy-4-(N,N-dimethylamino)benzaldehyde (2-MDMABA) has been investigated by steady state absorption and emission spectroscopy, time resolved emission spectroscopy and quantum chemical calculations. The molecule 2-MDMABA having a weak acceptor aldehyde group shows strong local emission in all solvents and a weak solvent polarity dependent red shifted emission in polar aprotic solvents for the charge transfer (CT) state which follows well the Lippert-Mataga equation. Instead of usual protonation at the donor site with inhibition of CT process, protonation at the acceptor aldehyde site enhances acceptor properties and hence increases excited state charge transfer reaction. The ground state structural calculation at Density Functional Theory (DFT) level with B3LYP functional and 6-31++ G** basis set and potential energy surfaces (PESs) following twisted intramolecular charge transfer model by using DFT method in the gas phase and in acetonitrile solvent have been performed for the neutral and cation to correlate with experimental findings.
Journal of Luminescence, 2012
The excited state charge transfer (CT) properties of p-Dimethylaminobenzaldehyde (DMABA) have been reinvestigated spectroscopically in combination with quantum chemical calculations. The molecule having weak acceptor group (-CHO) shows weak charge transfer emission, which follows linear dependency on solvent polarity parameters and E T (30) values. However, previously reported CT emission of DMABA in ACN and in DMF solvents by Grabowski et al. (Chem. Rev. 103 (2003) 3899) and Kawski et al. (Chem. Phys. Lett. 448 (2007) 208) are ambiguous and are different from the Grabowski's previous studies (Pure Appl. Chem. 55 (1983) 245) and the present results. Theoretical potential energy surfaces along both the donor and acceptor twisting motion using Density Functional Theory (DFT) with B3LYP functional and 6-311þþG nn basis set following Twisted Intramolecular Charge Transfer model support our experimental results. Time Dependent Density Functional Theory Polarization Continuum Model (TDDFT-PCM) has been used to explore the solvent effect on the emission spectra of DMABA.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2010
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.
Chemical Physics, 2007
In this work, we have studied the twisted intramolecular charge transfer process in ethyl ester of N,N 0-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.
Journal of the Serbian Chemical Society
The substituent and solvent effects on solvatochromism in 3-[(4-substituted)phenylamino]isobenzofuran-1(3H)-ones were studied using experimental and theoretical methodologies. The effect of specific and non-specific solvent-solute interactions on the shifts of UV-Vis absorption maxima were evaluated using the Kamlet-Taft and Catalán solvent parameter sets. The experimental results were studied by density functional theory (DT) and time-dependent density functional theory (TD-DFT). The HOMO/LUMO energies (E HOMO /E LUMO) and energy gap (E gap) values, as well as the mechanism of electronic excitations and the changes in the electron density distribution in both ground and excited states of the investigated molecules were studied by calculation in the gas phase. The electronic excitations were calculated by the TD-DFT method in the solvent methanol. It was found that both substituents and solvents influence the degree of π-electron conjugation of the synthesized molecules and affect the intramolecular charge transfer character.
Chemical Physics, 2006
A donor acceptor substituted aromatic system trans-3-(4-monomethylamino-phenyl)-acrylonitrile (MMAPA) has been synthesized and its photophysical behavior has been investigated in the solvent of different polarity by steady state absorption and emission, time-resolved emission and quantum chemical calculations. The observed dual fluorescence of MMAPA in polar aprotic solvents has been assigned to emission from the locally excited and twisted intramolecular charge transfer states. The low-energy emission in protic solvent is attributed to the hydrogen-bonded complex. Potential energy surfaces for the ground and excited states along the donor (-NHMe group) and acceptor (acrylonitrile group) twist coordinates have been calculated by time-dependent density functional theory (TDDFT) and time-dependent density functional theory-polarized continuum model (TDDFT-PCM) in the gas phase and in acetonitrile solvent, respectively. Calculations predict that the stabilized excited state along the twist coordinate is responsible for the solvent dependent red shifted charge transfer emission. It is found that the twisting along the donor site is energetically favorable compared to that of the acceptor site. The canonical crossing of the excited states for the twisting of the donor group and localized nitrogen lone pair orbital of-NHMe group at the perpendicular configuration with respect to p-orbitals of benzene ring support TICT model for photo-induced charge transfer reaction in MMAPA molecule.
… of Photochemistry and …, 2010
Ammonium N-(3,5-dinitrobenzoyl)-␣-phenylglycinate adducts were synthesized and characterized by using different protonated amines as counter-ion: NH 4 + , (process was observed under ultraviolet ( exc , 254 nm) or solar irradiation, both in solid state and in solution: DMSO, acetone or acetonitrile. 3,5-Dinitrobenzene and carboxylate groups, separated by an N-benzylamide bridge, are present in these adducts, acting as electron acceptor and electron donor, respectively. Spectroscopic analyses (NMR, IR and UV-vis) suggest a photoinduced intramolecular electron transfer. A first-order photochemical kinetics was proposed in DMSO/(n-propylammonium N-(3,5-dinitrobenzoyl)-␣-phenylglycinate) solution; such behavior was similar for all adducts studied, probably due to total salt dissociation in solution. In the solid state, however, electron transfer process efficiency is directly proportional to Lewis base (amine) strength of the adduct counter-ion. Decarboxylation is observed after the irradiation process, giving rise to aadduct intermediate, and subsequent formation of benzaldehyde and 3,5-dinitrobenzamide degradation products.
Article Synthesis and Photophysical Properties of the 2-(3-(2-Alkyl-6,8
2014
Iodine-catalyzed condensation of 2-amino-3,5-dibromobenzamide with cyclohexane-1,3-dione derivatives in refluxing toluene afforded the corresponding bisquinazolinones. Suzuki-Miyaura cross-coupling of the latter with arylboronic acids afforded tetraarylbisquinazolinones. The electronic absorption and emission properties of these tetraarylbisquinazolinones were measured in dimethylsulfoxide (DMSO) and acetic acid by means of UV-Vis and fluorescence spectroscopic techniques in conjunction with quantum chemical methods to understand the influence of substituents on intramolecular charge transfer (ICT).