Van der Waals complexes of xanthione and benzopyranthione with rare gases. S2S0 fluorescence excitation spectroscopy and microscopic solvation effects

Ludwiczak, M.; Sinha, Hemant K.; Steer, Ronald P.

doi:10.1016/0009-2614(92)85534-h

Cited by 14 publications

(18 citation statements)

References 34 publications

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“…Thus dispersive interactions are likely to provide the most important contributions to the binding energy in this species: The large polarizability of ground state ClzCS (10.2 A~) (25) is consistent with this view. A similar conclusion was reached recently in the case of van der Waals complexes of aromatic thiones with rare gas atoms (49), and supports in a general way the approach that Morokuma (5,50) has taken in analyzing and describing intermolecular interactions. Theoretical calculations of the energies of van der Waals dimers of various possible geometries would be most useful for interpreting these experimental data.…”

Section: Lo-'supporting

confidence: 85%

Thiophosgene monomer–dimer equilibria in perfluoroalkane solutions: spectroscopic and photophysical implications of self-association in the ground state

Maciejewski¹,

Szymański²,

Steer³

1993

Can. J. Chem.

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The S2–S0 absorption, emission, and emission excitation spectra of thiophosgene in a perfluoroalkane solvent have been measured as a function of the analytical concentration, C, of the solute. Strong evidence of the formation of van der Waals dimers at 10−4 M < C < 10−1 M and of higher oligomers at C > 10−1 M has been found. Variations in the absorption spectra at C < 10−1 M have been analyzed successfully in terms of a single [Formula: see text] equilibrium, for which the value of K is (5.0 ± 0.4) × 102 M−1 at 295 K. The mole fractions of monomer and dimer have been calculated at each C, and have been used to construct the absorption spectrum of the dimer. Both the monomer and dimer have similar S0 → S1, and S0 → S2 absorption spectra, but the dimer has an oscillator strength that is about twice that of the monomer. The effects of self-aggregation on the S2–S0 emission and excitation spectra have been analyzed. Absorption by the dimer in the ultraviolet also leads to emission, but with a different quantum efficency compared with direct excitation of the monomer. The implications of these observations on the interpretation of the spectroscopy, photophysics, and photochemistry of thiophosgene in solution are assessed.

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Section: Lo-'supporting

confidence: 85%

Thiophosgene monomer–dimer equilibria in perfluoroalkane solutions: spectroscopic and photophysical implications of self-association in the ground state

Maciejewski¹,

Szymański²,

Steer³

1993

Can. J. Chem.

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“…detection, and data acquisition systems have been described in previous publications (13,17). Briefly, the vapor from a Ab initio force field calculations were performed at the STO-3G** and CEP-31G (effective core potential) levels heated sample of the thione is entrained in a stream of He and is admitted to a high-vacuum chamber through a pulsed using the Gaussian 92 suite of programs (18).…”

Section: Theoretical Methodsmentioning

confidence: 99%

“…1) with selected polar and nonpolar solvent mole-dent power spectrum using a pyroelectric detector. Wavecules (13)(14)(15). These initial studies were directed toward number calibration was effected with a home-built optogalunraveling the structures of the van der Waals complexes vanic detector which observed laser-excited Fe resonances and understanding the details of the intermolecular interac-in a commercial Fe-Ne hollow cathode lamp.…”

Section: Introductionmentioning

confidence: 99%

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S2–S0Spectra of Jet-Cooled Xanthione and Benzopyranthione: Microscopic Solvation by Rare Gases

Sinha

Steer

1997

Journal of Molecular Spectroscopy

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“…However, in MAz the origin band is extremely weak and the spectral shift was therefore measured relative to the stronger transition, which lies 355 cm -1 to the blue of the origin . By analogy with the spectra of the rare gas complexes of azulene 10 and many other systems, ,,, the additional weak bands lying immediately to the red of strong features found in the spectra of the bare molecule are assigned to the origin and progressions in one or more excited state van der Waals vibrations of the 1:1 complex. For each group of such red-shifted bands, the one of relatively high intensity furthest displaced from the corresponding feature in the bare molecule is taken as the origin of the 1:1 complex.…”

Section: Resultsmentioning

confidence: 99%

Van der Waals Complexes of 2-Chloro-, 2-Methyl-, and 1,3-Dimethylazulene with Rare Gases: Microscopic Solvent Shifts, Structures, and Binding Energies

1997

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The S2−S0(1La) fluorescence excitation and emission spectra of the van der Waals complexes of three azulene (Az) derivatives, 2-chloroazulene (ClAz), 2-methylazulene (MAz), and 1,3−dimethylazulene (DMAz), with the rare gases, Ar, Kr, and Xe, have been measured under jet-cooled conditions. The microscopic solvent shifts, δν̄, of the origin bands in the S0−S2 spectra associated with complexation of the chromophores with one and two rare gas atoms increase with increasing polarizability of the adatom(s), consistent with the dominance of dispersion in the binding. Although there are substantial variations in the relative values of δν̄ among the Az derivatives examined, all of the δν̄ values are relatively small and are similar to those of the 1Lb(S0−S1) transitions in the rare gas complexes of naphthalene and its methyl-substituted derivatives. The theory of microscopic solvent shifts of Jortner et al. has been used to analyze the solvent shift data. Comparisons of the sources of the oscillator strengths and van der Waals binding interactions in the azulene− and naphthalene−rare gas systems are revealing and suggest that the variations in δν̄ with substitution pattern are primarily electronic in their origin and arise from variations in excited state configuration interactions, the magnitude of which depend on the S2−S n energy spacings. These spacings can be varied by placing substituents either along the long axis (2-position) or parallel to the short axis( 1,3-positions) so that they selectively perturb, respectively, the long axis polarized and the short axis polarized transitions. The structures and binding energies of the complexes of these derivatives have also been modeled using Lennard-Jones type calculations and have been compared with those of Az itself. The observed progressions in the low-frequency intermolecular vibrations in each case are assigned to that excited state bending mode which is parallel to the long axis of the chromophore, in agreement with model calculations using one-dimensional Morse and Taylor's series potential functions.

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Van der Waals complexes of xanthione and benzopyranthione with rare gases. S2S0 fluorescence excitation spectroscopy and microscopic solvation effects

Cited by 14 publications

References 34 publications

Thiophosgene monomer–dimer equilibria in perfluoroalkane solutions: spectroscopic and photophysical implications of self-association in the ground state

Thiophosgene monomer–dimer equilibria in perfluoroalkane solutions: spectroscopic and photophysical implications of self-association in the ground state

S2–S0Spectra of Jet-Cooled Xanthione and Benzopyranthione: Microscopic Solvation by Rare Gases

Van der Waals Complexes of 2-Chloro-, 2-Methyl-, and 1,3-Dimethylazulene with Rare Gases: Microscopic Solvent Shifts, Structures, and Binding Energies

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