Excited State Molecular Parameters Determined by Spectral Means

Abstract

The possibility to characterize the electronic excited state of a spectrally active molecule based only on the solvatochromic study of electronic absorption spectra is demonstrated. The values of the regression coefficients given the contribution of universal interactions to the spectral shift and their theoretically established dependences on the solute molecule microscopic parameters are used. The values of the dipole moment, polarizability, and ionization potential in the ground electronic state of a spectrally active molecule are established by quantum mechanical methods. Two azo dye molecules are chosen in order to exemplify this method.

Some Aryl-1,2,4-triazol-1-ium Phenacylids in Binary Hydroxyl Solvent Mixtures. Computational and Spectral Study

“…This study was conducted in order to use the values of the correlation coefficients C 1 and C 2 for estimating the excited state electric dipole moment of the studied ylids and for approximating the angle between the dipole moments in the electronic states responsible for the absorption process of the visible photons. The procedure described in [30,33] was applied for these calculations.…”

“…The results obtained for estimating the excited dipole moment of the studied ylids for the visible absorption transitions using relations ( 7) and ( 8), the molecular parameters from Tables 2-5 and the procedure described in [30,33], are given in Table 10. The values of the excited state dipole moments were obtained, hypothesizing that the excited state polarizability must be a positive parameter as it results from its definition for the case of PTPY and TTPY and in the hypothesis of McRae [31] and Kawski [34] (in the time of electronic transition the molecular polarizability is the same in the electronic state participating to the absorption transition) for ylids PTNPY and TTNPY.…”

Variational Method for Estimating the Dipole Moment in the Second Excited State of Fluorescein Molecule from its Electronic UV Absorption Spectra

“…The experimental values of the wavenumbers in the maximum of the UV band of fluorescein in different solvents are listed in Tables 5. The total shift of the electronic bands can be described by the following relation [50][51][52][53]: (1) where ν o (cm -1 ) has the significance of the wavenumber in the maximum of absorption electronic band for gaseous phase of the spectrally active substance and C 1 -C 4 are the regression coefficients obtained by multilinear regression analysis. The terms C 1 f(ε) and C 2 f(n) give the contribution of the universal interactions by orientation-induction and polarization-dispersion processes, respectively, while the terms C 3 β and C 4 α give the contribution of the specific interactions to the total spectral shift.…”

New QSAR and Solvatochromic Estimation of Molecular Parameters of Chlortetracycline

“…The statistical analysis of the solvatochromic data can also be used in order to determine the excited state dipole moment pe and the angle φ between the dipole moments pg and pe in the two electronic states participating to the π-π‫٭‬ transition, by a variational method [27,28].…”

“…From the multitude of the obtained results, one chooses the value at which the electric polarizability becomes equal (or approximate equal) with the ground state electric polarizability [27,28]. At φ=71.50 0 the polarizability from the excited state equalizes the ground state polarizability of CTC.…”