scholarly journals Solvent Effect on the Fluorescence Properties of Two Biologically Active Thiophene Carboxamido Molecules

2013 ◽  
Vol 12 (1) ◽  
pp. 49-68 ◽  
Author(s):  
D Nagaraja ◽  
H S Geethanjali ◽  
N R Patil ◽  
F M Sanningannavar ◽  
R A Kusanur ◽  
...  
Keyword(s):  
Fluorescence Spectra ◽  
Room Temperature ◽  
Dipole Moments ◽  
Stokes Shift ◽  
Solvent Polarity ◽  
Biologically Active ◽  
Solvatochromic Shift ◽  
Shift Method ◽  
Polarity Parameter ◽  
Constant E

The absorption and fluorescence spectra of two thiophene carboxamido molecules namely 2–( - trimethoxy phenyl) imino–3–N–ethylcarboxamido–4, 5, tetramethylene thiophene (X) and 2-( -N, N-dimethylaminophenyl) imino-3-(N- methylphenyl carboxamido)-4, 5, tetramethylene thiophene (Y) have been recorded at room temperature. The ground (mg) and excited (me) state dipole moments are estimated from Lippert, Bakhshiev, Kawski-Chamma-Viallet equations by using the variation of Stokes shift with microscopic solvent dielectric constant (e) and refractive index (n). The excited dipole moments were also estimated by using the variation of Stokes shift with microscopic empirical solvent polarity parameter and the values are compared. It was estimated that dipole moments of the excited state were higher than those of the ground state of both the molecules. Further, the change in dipole moment (Dm) were calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter .

Solvent effect on the dipole moments and photo physical behaviour of 2,5-di-(5-tert-butyl-2-benzoxazolyl) thiophene dye

2013 ◽  
Vol 91 (12) ◽  
pp. 1107-1113 ◽  
Author(s):  
J.S. Kadadevarmath ◽  
G.H. Malimath ◽  
N.R. Patil ◽  
H.S. Geethanjali ◽  
R.M. Melavanki
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Dipole Moments ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Solvatochromic Shift ◽  
Shift Method ◽  
Tert Butyl ◽  
Solvatochromic Shift Method ◽  
Polarity Parameter

The absorption and emission spectra of fluorescent thiophene dye, namely, 2,5-di-(5-tert-butyl-2-benzoxazolyl) thiophene, have been recorded at room temperature in solvents of different polarities. The excited state dipole moments (μe) were estimated from Lippert’s, Bakhshiev’s, and Kawski–Chamma–Viallet’s equations using the variation of Stoke’s shift with the solvent dielectric constant and refractive index. The optimized geometry of the molecule and μg were calculated theoretically by Gaussian 03 software using B3LYP/6-31g* level of theory. The μg and μe were calculated by means of solvatochromic shift method and μe was determined in combination with μg. It was observed that μe were higher than those of the μg, indicating a substantial redistribution of the π-electron densities in a more polar excited state for the selected thiophene dye. Further, the change in the dipole moment (Δμ) was calculated both from solvatochromic shift method and on the basis of microscopic empirical solvent polarity parameter [Formula: see text] and values are compared.

Photophysical characteristics of two novel coumarin derivatives: Experimental and theoretical estimation of dipole moments using the solvatochromic shift method

2014 ◽  
Vol 92 (11) ◽  
pp. 1330-1336 ◽  
Author(s):  
Shivaram N. Patil ◽  
F.M. Sanningannavar ◽  
B.S. Navati ◽  
N.R. Patil ◽  
R.A. Kusanur ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Dipole Moments ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Spectral Shift ◽  
Coumarin Derivatives ◽  
Solvatochromic Shift ◽  
Shift Method ◽  
Solvatochromic Shift Method

The exited state (μe) dipole moment of a molecule is an important parameter, which gives information about electronic and geometrical structure of the molecule in the short-lived state. We have experimentally estimated the exited state (μe) dipole moment of two novel coumarin derivatives, namely, diethyl 2-acetamido-2-((6-methyl-2-oxo-2H-chromen-4-yl) methyl) malamute (DAM) and 5,6-Benzo-3-[1-(4,5-dicarbomethoxy-1,2,3-triazoloacetyl)] coumarin (5BDTC) by three methods, namely, Lippert’s, Bakhshiev’s, and Kawski–Chamma–Viallet’s. In the Solvatochromic shift method, spectral shift is due to internal excitation of the molecule. We have recorded absorption and emission spectra of the above two novel coumarin derivatives at room temperature using solvents of different polarities. The geometry of the molecules were fully optimized and the ground state dipole moment (μg) were also calculated theoretically by Gaussian 03 software using B3LYP/6-31g* level of theory. The excited state dipole moment was calculated using CIS/6-31G* level of theory. The μg and μe were calculated using the solvatochromic shift method and μe was also determined in combination with μg. It was observed that μe were greater than those of μg, indicating a substantial redistribution of the π-electron densities in a more polar excited state for this coumarin. Further, the changes in dipole moment (Δμ) were calculated both from the solvatochromic shift method and on the basis of microscopic empirical solvent polarity ([Formula: see text]) and the values are compared.

scholarly journals Spectral Properties of Hybrid of Rhodamine (6G) Dyes Doped Epoxy Resin Dissolved in Chloroform

2019 ◽  
Vol 16 (3(Suppl.)) ◽  
pp. 0764 ◽  
Author(s):  
Al-Hamdani Et al.
Keyword(s):  
Epoxy Resin ◽  
Quantum Efficiency ◽  
Fluorescence Spectra ◽  
Room Temperature ◽  
Rhodamine 6G ◽  
Energy Gap ◽  
Radiative Lifetime ◽  
Stokes Shift ◽  
Fluorescence Emission ◽  
Absorption And Fluorescence Spectra

            The research is dealing with the absorption and fluorescence spectra for the hybrid of  an Epoxy Resin doped with organic dye Rhodamine (R6G) of different concentrations (5*10-6, 5*10-5, 1*10-5, 1*10-4, 5*10-4) Mol/ℓ at room temperature. The Quantum efficiency Qfm, the rate of fluorescence emission Kfm (s-1), the non-radiative lifetime τfm (s), fluorescence lifetime τf and the Stokes shift were calculated. Also the energy gap (Eg) for each dye concentration was evaluated. The results showed that the maximum quantum efficiency 62 % and maximum stokes shift 96 nm was obtained in dye concentration 5*10-6 and 1*10-4. The energy gap ranges between 1.066 eV to 1.128 eV depending proportionally on the dye concentrations.

scholarly journals Studies on Photophysical Properties of Mono-carbonyl Curcumin Analogues: Experimental and Theoretical approach

2018 ◽  
Vol 34 (4) ◽  
pp. 2170-2179
Author(s):  
Manjula Rayanal ◽  
Prasad Pralhad Pujar ◽  
Sridhar D
Keyword(s):  
Excited State ◽  
Ground State ◽  
Dipole Moments ◽  
Photophysical Properties ◽  
Stokes Shift ◽  
Solvent Polarity ◽  
Frontier Molecular Orbital ◽  
Curcumin Analogues ◽  
Td Dft ◽  
Ground State Dipole Moments

The solvatochromic fluorescence behaviour of mono-carbonyl curcumin analogues has been studied in ten different solvents ranging from non-polar to polar. The solvent effect on the spectral properties of analogues has been discussed. The ground state dipole moments were estimated experimentally by Bilot-Kawski equation which is a function of Stokes shift with the solvent polarity parameters and Guggenheim method and theoretically by TD-DFT studies. The excited state dipole moment was determined using Bilot-Kawski equations. The excited state dipole moments for the two molecules were found to be higher than their corresponding ground state dipole moments. Theoretically Frontier molecular orbital (HOMO/ LUMO) energies were determined by Gaussian 09 W software using TD-DFT.

Solvent Effects upon the Electronic Absorption and Fluorescence Spectra of Pteridines and Riboflavin and Their Ground and First Excited Singlet State Dipole Moments

Pteridines ◽  
1991 ◽  
Vol 3 (3) ◽  
pp. 153-163 ◽  
Author(s):  
J.-J. Aaron ◽  
M. D. Gaye ◽  
C. Párkányi ◽  
C. Boniface ◽  
T. W. N Bieze ◽  
...  
Keyword(s):  
Electronic Absorption ◽  
Singlet State ◽  
Dipole Moments ◽  
Stokes Shift ◽  
Fluorescence Emission ◽  
Excited Singlet State ◽  
Theoretical Ground ◽  
Excited Singlet ◽  
Solvatochromic Shift ◽  
Wide Range

The electronic absorption. fluorescence excitation, and fluorescence emission spectra of a series of pteridines (lumazine, xanthopterin, isoxanthopterin, biopterin) and riboflavin (vitamin B2) were measured at room temperature (298 K) in a number of solvents covering a wide range of polarities (dioxane, ethyl ether, chloroform, ethyl acetate, 1-butanol. 2-propanol, ethanol, methanol, dimethylformamide, acetonitrile, and dimethyl sulfoxide). The effects of the solvent upon the spectral properties are discussed. Experimental groundstate dipole moments were measured for selected compounds and were used in combination with the spectral data to evaluate their first excited singlet-state dipole moments by means of the solvatochromic shift method (Bakhshiev's and Kawski-Chamma-Viallet's equations based on the variation of the Stokes shift with the solvent dielectric constant-refractive index term). The theoretical ground and excited singlet-state dipole moments for all pteridines and riboflavin were calculated as a vector sum of the π-component (obtained by the PPP method) and the a-component (obtained from a-bond moments). A second set of theoretical values was obtained by using the CNDO/2method. A good agreement was observed between the experimental and the theoretical values. Excited singlet-state dipole moments are higher than the ground state values by 1 to 6 Debye units for all the pteridines under study with the exception of xanthopterin.

Determination of ground and excited state dipole moments of some naphthols using solvatochromic shift method

2011 ◽  
Vol 163 (3) ◽  
pp. 141-146 ◽  
Author(s):  
R. Gahlaut ◽  
N. Tewari ◽  
J.P. Bridhkoti ◽  
N.K. Joshi ◽  
H.C. Joshi ◽  
...  
Keyword(s):  
Excited State ◽  
Dipole Moments ◽  
Solvatochromic Shift ◽  
Shift Method ◽  
Solvatochromic Shift Method ◽  
Excited State Dipole Moments

The Electric Dipole Moments of Methine Dyes – Comparison of Experimental Results with Theoretical Predictions

1982 ◽  
Vol 37 (9) ◽  
pp. 1024-1026
Author(s):  
Z. Salamon ◽  
A. Skibiński ◽  
K. Celnik
Keyword(s):  
Dipole Moments ◽  
Stokes Shift ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Electronic Charge ◽  
Excited Singlet ◽  
Nonpolar Solvents ◽  
Singlet States ◽  
Theoretical Predictions ◽  
Excited Singlet States

Abstract Absorption and emission spectra of methine dyes in polar and nonpolar solvents were measured. From the Stokes shift as a function of solvent polarity the dipole moments of excited singlet states have been estimated and compared with the quantum chemical predictions. Also the π-electronic charge distribution in the ground and first excited singlet electronic states and bond orders of the dyes were calculated. All investigated methines showed an increase in dipole moment upon excitation to the first excited emitting state.

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