Solvation Dynamics of Coumarin 480 in Sol−Gel Matrix

Pal, Samir Kumar; Sukul, Dipankar; Mandal, Debabrata; Sen, and Sobhan; Bhattacharyya, Kankan

doi:10.1021/jp993484y

Cited by 72 publications

(105 citation statements)

References 39 publications

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“…10 One consistent conclusion of their studies is that there is not a one-to-one correspondence between steady-state spectra and the time-dependent Stokes shift function, S(t): ''...steady-state spectroscopy may not always be a good predictor for dynamical behavior.'' 14 Bhattacharyya and co-workers have measured the timedependent fluorescence of the dye molecule, Coumarin 480, in solventless zeolites, 4 aqueous micelles 5 and reverse micelles, 6 in water pools in a sol-gel matrix, 7 and vesicles. 8 They found that the long-time solvation dynamics depend strongly on the environment with a long-time decay of ϳ0.8 ns in the sol-gel matrix, 7 0.6 -2.4 ns in micelles ͑using different surfactants͒, 5 8 -12 ns in reverse micelles, 6 11 ns in vesicles, 8 and ϳ15.4 ns in the solventless zeolites.…”

Section: Experimental Workmentioning

confidence: 99%

Simulations of time-dependent fluorescence in nano-confined solvents

Thompson

2004

The Journal of Chemical Physics

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The time-dependent fluorescence of a model diatomic molecule with a charge-transfer electronic transition in confined solvents has been simulated. The effect of confining the solvent is examined by comparing results for solutions contained within hydrophobic spherical cavities of varying size ͑radii of 10-20 Å͒. In previous work ͓J. Chem. Phys. 118, 6618 ͑2002͔͒ it was found that the solute position in the cavity critically affects the absorption and fluorescence spectra and their dependence on cavity size. Here we examine the effect of cavity size on the time-dependent fluorescence, a common experimental probe of solvent dynamics. The present results confirm a prediction that motion of the solute in the cavity after excitation can be important in the time-dependent fluorescence. The effects of solvent density are also considered. The results are discussed in the context of interpreting time-dependent fluorescence measurements of confined solvent systems.

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Section: Experimental Workmentioning

confidence: 99%

Simulations of time-dependent fluorescence in nano-confined solvents

Thompson

2004

The Journal of Chemical Physics

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“…30,31 In particular, these coumarins have been widely used as excited-state electron acceptors to study electron transfer from electron-donating solvents such as aromatic amines. 7,[32][33][34][35][36][37] Another application of the 7-aminocoumarins, especially the 3-carboxylic acid derivatives, has been as photosensitizing dyes for wide band gap semiconductors such as TiO 2 and ZnO. 24,[38][39][40][41][42] Excited-state proton-transfer reactions have also been widely studied using 7-aminocoumarins.…”

Section: Introductionmentioning

confidence: 99%

Time-Dependent Density Functional Theory Investigation of the Ground and Excited States of Coumarins 102, 152, 153, and 343

2002

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We present calculations of various properties of the ground and excited electronic states of coumarins 102, 152, 153, and 343. Using density functional theory (DFT) and time-dependent density functional theory (TDDFT), we examine the excitation energies to the S 1 and S 2 states, the ground and excited-state dipole moments, and the lowest ionization potentials of these coumarins. In the case of C153, we locate two distinct S 0 minima due to differing conformations of the julolidyl ring structure and compare properties for the syn and anti conformers. For C343, we examine the possibility of proton transfers in the ground and S 1 states of the system. We find that (1) DFT tends to overestimate the ground-state dipole moments in these systems, (2) excellent agreement is obtained between TDDFT and experimental vertical excitation energies, (3) TDDFT and CIS yield similar estimates of the dipole moment change between the S 0 and S 1 states, both of which are in the range of previous experimental estimates, (4) in each case, the S 2 state is at least 0.5 eV above the S 1 state for the ground-state geometry, and (5) proton transfer is not likely in the ground state of C343 but is only 0.18 eV higher in energy in the S 1 state. We also compare the DFT/TDDFT results with RHF/CIS, MP2, and INDO S/CI results. We find good agreement between MP2 and experimental ground-state dipole moments and good agreement between INDO S/CI and TDDFT gas-phase excitation energies.

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“…The kinetics of hydrolytic, oxidation, and reduction reaction may also be significantly influenced by the reverse micelles [7,8]. Among the various surfactants present, most of the experiments have been done on sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) [9][10][11][12][13][14][15][16]. Although potentially important, reverse micelles of the surfactants other than AOT are rare in the literature.…”

Section: Introductionmentioning

confidence: 99%