Photophysical properties and estimation of ground and excited state dipole moments of 7-diethylamino and 7-diethylamino-4-methyl coumarin dyes from absorption and emission spectra (original) (raw)
Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2008
The effect of solvents on the absorption and emission spectra of ergone has been studied in various solvents at 298 K. The bathochromic shift was observed in absorption and fluorescence spectra with the increase of solvents polarity, which implied that transition involved was → *. And the normalized transition energy value E N T showed some scattering when plotted versus . The ground state and excited state dipole moments were calculated by quantum-mechanical second-order perturbation method as a function of the dielectric constant (ε) and refractive index (n). The result was found to be 1.435 D and 2.520 D in ground state and excited state respectively. And also, the density functional calculations were used to obtain the ground state and excited state dipole moments for it has proven to be suitable for calculating electronic excitation energy. And the result is consistent with the experimental.
Effect of binary solvent mixtures (DMSO/water) on the dipole moment and lifetime of coumarin dyes
Journal of Molecular Structure, 2008
Absorption and fluorescence spectra of four coumarin laser dyes, Coumarin 440 (C440), Coumarin 450 (C450), Coumarin 466 (C466) and Coumarin 151 (C151), have been recorded in binary mixtures of DMSO and water at room temperature (298 K) to study the solvent effect and to evaluate the ground and excited state dipole moments using solvatochromic shift method. The anomalous feature in the complex systems of these mixtures due to the structural heterogeneities is discussed. The effect of solvent polarity parameters of binary mixture on the ground and excited state dipole moments was examined. Experimental results indicate that the dipole moments in the excited state, for all the molecules investigated, are higher than the corresponding values in the ground state. The ground and excited state dipole moments of these probes have also been computed from ab initio calculations and compared with those obtained experimentally. Fluorescence lifetimes of all the probes measured using time domain fluorescence spectrometer employing time correlated single photon counting technique, show a nonlinear variation with the composition of binary mixture.
European Journal of Chemistry, 2012
The effects of solvents of various polarity on the electronic absorption and fluorescence spectra of 7-hydroxy-4-trifluoromethyl coumarin; 6,7-dihydroxy-4-trifluoromethyl coumarin and 7-methoxy-4-trifluoromethyl coumarin have been investigated. The singlet-state excited dipole moments (μe) and ground state dipole moments (μg) are estimated from Bakshiev and Kawski-Chamma-Viallet equations by using the variation of Stokes' shift with the solvent's dielectric constant (ε) and refractive index (n). The observed singlet-state excited dipole moments are found to be larger than the ground-state ones. In addition, the geometry and other electronic properties are computed using ab-initio method with correlation functions at 6-31G basis set.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
The solvent effects on the electronic absorption and fluorescence emission spectra of several coumarins derivatives, containing amino, N,N-dimethyl-amino, N,N-diethyl-amino, hydroxyl, methyl, carboxyl, or halogen substituents at the positions 7, 4, or 3, were investigated in eight solvents with various polarities. The first excited singlet-state dipole moments of these coumarins were determined by various solvatochromic methods, using the theoretical ground-state dipole moments which were calculated by the AM1 method. The first excited singlet-state dipole moment values were obtained by the Bakhshiev, Kawski-Chamma-Viallet, Lippert-Mataga, and Reichardt-Dimroth equations, and were compared to the ground-state dipole moments. In all cases, the dipole moments were found to be higher in the excited singlet-state than in the ground state because of the different electron densities in both states. The redshifts of the absorption and fluorescence emission bands, observed for most compounds upon increasing the solvent polarity, indicated that the electronic transitions were of-* nature.
Effect of anisotropic and isotropic solvent on the dipole moment of coumarin dyes
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011
The ground state ( g ) and the excited state ( e ) dipole moments of two coumarin laser dyes, coumarin 440 and 460, were studied at room temperature in various solvents, viz., general solvents, alcohols and liquid crystals at 298 K. In this work, we report dipole moment of laser dyes in different anisotropic (liquid crystal) and isotropic environments for understanding the effects of environments on the molecular dipole moment and comparing them. Ground and excited state dipole moments of coumarin dyes were evaluated by means of solvatochromic shift method. It was observed that dipole moment values of excited states ( e ) were higher than the corresponding ground state values ( g ) in all media.
Luminescence : the journal of biological and chemical luminescence, 2017
The UV/Vis absorption and fluorescence characteristics of 3-cyano-7-hydroxycoumarin [CHC] and 7-amino-4-methyl-3-coumarinylacetic acid [AMCA-H] were studied at room temperature in several neat solvents and binary solvent mixtures of 1,4-dioxane/acetonitrile. The effects of solvent on the spectral properties are analyzed using single and multi-parameter solvent polarity scales. Both general solute/solvent interactions and hydrogen bond interactions are operative in these systems. The solvation of CHC and AMCA-H dyes in 1,4-dioxane/acetonitrile solvent mixtures has been studied. The solutes CHC and AMCA-H are preferentially solvated by acetonitrile and a synergistic effect is observed for both molecules in dioxane/acetonitrile solvent mixtures. In addition, using the solvatochromic method the ground- and the excited-state dipole moments of both the dyes were calculated. The ground- and excited-state dipole moments, absorption and emission maxima and HOMO-LUMO gap were also estimated t...
The ground state (μg) and excited state (μe) dipole moments of two coumarin derivatives namely diethyl 2- acetamido-2-((3-oxo-3H-benzo[f]chromen-1-yl)methyl)malonate (2DAM) and ethyl2-((7-methyl-2-oxo-2H-chromen-4- yl)methyl)-3-oxobutanoate ) were estimated in various solvents. The dipole moments were estimated from Lippert, Bakhshiev and Kawaski-Chamma-Viallet equations by using the variation of stokes shift with the solvent dielectric constant and refractive index. Ground state dipole moments were also calculated theoretically by DFT studies using Gaussian 03 software. It was observed that the excited state dipole moments calculated by solvatochromic shift method were greater than the ground state dipole moments indicating a substantial redistribution of the -electron densities in a more polar excited state for both the coumarin derivatives.
Influence of solvent and substituent on excited state characterstics of laser grade coumarin dyes
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2003
Absorption and fluorescence emission of 4 and 7 substituted coumarins viz. C 440, C 490, C 485 and C 311 have been studied in various polar and non-polar organic solvents. These coumarin dyes are substituted with alkyl, amine and fluorine groups at 4-and 7-positions. They give different absorption and emission spectra in different solvents. The study leads to a possible assignment of energy level scheme for such coumarins including the effect on ground state and excited state dipole moments due to substitutions. Excited state dipole moments of these dyes are calculated by solvetochromic data experimentally and theoretically these are calculated by PM 3 method. The dipole moments in excited state, for all molecules investigated here, are higher than the corresponding values in the ground state. The increase in dipole moment has been explained in terms of the nature of excited state and resonance structure. #
European Journal of Chemistry, 2012
The effect of solvents on absorption and fluorescence spectra and dipole moments of two medium sized dipolar laser dyes 2-(2,7-dichloro-6-hydroxy-3-oxo-3H-xanthen-9-yl) benzoic acid (Fluorescein 27) (F27) and N-[6-diethylamino)-9-(2,4-disulfophenyl)-3H-xanthen-3ylidene]-N-ethylhydroxid (Sulfarhodamine B) (SRB) have been studied comprehensively in polar protic and polar aprotic solvents at room temperature (298 K). The bathochromic shift observed in absorption and fluorescence spectra of F27 and SRB with increasing solvent polarity signifies that the transition involved are π→π*. Solvatochromic correlations were used to obtain the ground and excited state dipole moments. The observed excited state dipole moments are found to be larger than their ground state counterparts in all the solvents studied. The ground and excited state dipole moments of these probes have also been computed from ab initio calculations and compared with those determined experimentally. Further, the experimentally obtained changes in dipole moment (Δμ) were compared with those using normalized polarity terms N T E from Reichardt equation. Dipolar dyes Stokes' shift Solvatochromic Solvent polarity Bathochromic shift Ground and excited state dipole moments