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1
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Photoinduced Charge-Transfer Reactions of Tricyanoethylene with Aromatic Hydrocarbon Electron Donors. II. Semiempirical Studies of Naphthalene-Tricyanoethylene Exciplex

100%
Deperasińska I., Prochorow J.
Acta Physica Polonica A
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2002
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vol. 102
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issue 6
811-826
EN
In this work we present the results of semiempirical AM1 calculations of the energy of electron-donor-acceptor system of naphthalene-tricyanoethylene complex in the ground and excited state with full optimization of the complex geometry. It was found that a ground state of the complex under consideration is stabilized almost exclusively by the electrostatic and Van der Waals interactions (presumably without charge-transfer resonance interaction). Its optimized equilibrium configuration has almost perpendicular head-to-face orientation of component molecules while in an excited state it is practically a charge-transfer electronic configuration with almost sandwich-like arrangement of both molecules. The energies of vertical electronic transitions between relevant ground and excited states and other spectroscopic parameters for these transitions were calculated with the use of ZINDO/S method and were compared with results of recent experimental observations of naphthalene-tricyanoethylene exciplex. This comparison led to a satisfactory explanation of the spectral properties and to a deeper insight into the kinetic parameters of the electron-donor-acceptor system under study.
2
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Excited States of Intermolecular Electron-Donor-Acceptor Systems and Internal Geometry of Complex' Components

100%
Deperasińska I., Sobieraj A.
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vol. 95
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issue 3
309-319
EN
In this work we present the results of semiempirical AM1 calculations of the energy of electron-donor-acceptor system in the ground and excited states with full optimization of the complex geometry (in terms of both: intermolecular and intramolecular coordinates). A comparison of these results with those obtained for separated acceptor and donor molecules enables the estimation of the energetic effects of changes in internal structure of donor and acceptor which accompany the process of formation and stabilization of excited charge-transfer state. It is shown that energies corresponding to those changes are comparable with the energy of intermolecular interactions between donor and acceptor molecules.
3
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Spectroscopy and Photophysics of Monoazaphenanthrenes II. Ab initio Analysis of Molecular Parameters and Electronic Spectra

100%
Deperasińska I., Prochorow J.
Acta Physica Polonica A
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2003
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vol. 104
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issue 6
601-613
EN
The ground state structures of phenanthrene and its monoaza-deriv atives, phenanthridine and 7,8-benzoquinoline were optimized using the ab initio methods. Both methods of optimization are leading to the results, which are in good agreement with available experimental data. Calculated ground-state electric dipole moments in phenanthridine and 7,8-benzoquinoline were found to have antiparallel orientations, due to the different electronic charge distributions in these molecules. The energies of vertical electronic transitions from the ground to excited singlet states (S_0 → S_n transitions) and the corresponding oscillator strengths were calculated within the framework of configuration interaction-singles and time-dependent density functional theory. The last method was found to be more accurate in reproduction of experimental absorption spectra. Very interesting result of these computations is the change of relative orientation of the transition dipole moments for the two lowest ππ* electronic transition in monoazaphenanthrenes - from perpendicular in phenanthrene molecule to nearly parallel orientation in both monoazaphenanthrenes. The observed changes of molecular parameters and spectra can be related to the inductive effects of the substitution of nitrogen atom into the aromatic skeleton of phenanthrene.
4
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Normal Mode Analysis of Vibrations of Jet-Cooled Acridine Dimer

100%
Deperasińska I., Prochorow J.
Acta Physica Polonica A
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2000
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vol. 97
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issue 2
285-294
EN
The analysis of normal modes of vibrations was performed for acridine dimer, which has been recently observed and identified by laser-induced emission spectroscopy under conditions of jet-cooling in a supersonic helium expansion. The frequencies and the forms of normal vibrations, computed with the use of the semi-empirical PM3 method are classifying all vibrations of acridine dimer into two distinct categories of inter- and intramolecular vibrations. There are six low-frequency intermolecular normal vibrations which are characterizing relative movements of two acridine moieties in the dimer and at least two of them have vibrational frequencies which are close to the frequencies of vibronic bands observed in the fluorescence excitation spectrum of the dimer. The intramolecular normal vibrations of the dimer very strictly correspond to the normal vibrations of acridine molecule (with a minor modification of the vibrational frequencies due to the splitting in the dimer). Furthermore, the intramolecular vibrations of acridine dimer, as well as the vibrations of acridine molecule are in good agreement with available experimental data (either IR and Raman spectra of acridine or fluorescence excitation spectrum of acridine dimer in supersonic jet). The results of the present analysis are very clearly supporting the previous conclusions concerning the ground-state equilibrium structure of acridine dimer formed under jet-cooling conditions.
5
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Analysis of the Origin Band of Acridine Dimer Fluorescence Excitation Spectrum - Conformations of Jet-Cooled Acridine Dimer

100%
Deperasińska I., Prochorow J.
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EN
The analysis of rotational band contour for the origin transition of fluorescence excitation spectrum of acridine dimer, earlier observed under conditions of jet-cooling in supersonic helium expansion, has been performed. An optimized ground-state equilibrium structure of acridine dimer fits the approximation of asymmetric top rigid rotor. In this approximation rotational constants were determined and an A-type rotational band was computed. It has turned out that the computed rotational band contour is much narrower than the experimental one. In search for the reasons of this discrepancy between calculations and experiment, an analysis of relative rotational motion of acridine moieties of the dimer was carried out. It was found that minima of potential energy curves for rotational motion, although very flat, under conditions of supersonic expansion can acquire (in their shallow local minima) non-vanishing population of slightly different conformations of the dimer. It was shown that in terms of non-statistical distribution of such populations, the origin bands of individual conformations may contribute to the experimental band contour.
6
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Fluorescence Spectra of 7,8-Benzoquinoline Isolated in the Supersonic Jet Expansion - An Ab Initio Analysis

81%
Deperasińska I., Prochorow J., Stepanenko Y.
Acta Physica Polonica A
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2004
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vol. 106
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issue 4
535-545
EN
The optimized equilibrium geometry of 7,8-benzoquinoline molecule in its first excited, S_1, singlet state was computed with the use of ab initio RCIS/6-31G(d) method. It was found that the electronic transition to the first excited state in 7,8-benzoquinoline is not confined to the neighborhood of nitrogen atom, but is delocalized over entire aromatic rings system, much alike in the molecule of phenanthrene. With the optimized geometry of the ground and excited state of the molecule, the frequencies of the vibrational fundamental modes were computed, together with their displacement parameters (geometry changes of vibrations between the excited and the ground state). These frequencies are in good agreement with vibrational frequencies present in the fluorescence spectrum of 7,8-benzoquinoline observed recently under jet-cooling conditions in supersonic beam expansion. In comparison to the fluorescence spectrum of phenanthrene, the calculated, as well as experimental fluorescence spectra of 7,8-benzoquinoline contain much more vibrational features, and this increased vibronic activity is related to the symmetry break caused by the introduction of N-heteroatom into the aromatic ring system of phenanthrene.
7
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Immunosuppressive influence of Anguillid herpesvirus-1 (AngHV-1) infection on cellular defense mechanisms in European eel (Anguilla anguilla)

81%
Schulz P., Deperasińska I., Kaczorek-Łukowska E., Siwicki A. K.
Polish Journal of Veterinary Sciences
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2019
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issue 4
8
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Theoretical Analysis of the Electronic Ground and Excited Franck-Condon State of 2-Alkylamino-(3, 5, or 6)-Methyl-4-Nitropyridine N-oxides

81%
Deperasińska I., Makarewicz A., Szemik-Hojniak A.
Acta Physica Polonica A
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2007
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vol. 112
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issue S
S-71-S-84
EN
We theoretically characterised properties of the electronic ground and excited Franck-Condon state of 2-alkylamino-(3, 5, or 6)-methyl-4- -nitropyridine N-oxides. The obtained results of time-dependent density functional theory calculations are consistent with the experimental absorption spectra. The nature of the lowest excited states of the considered N-oxides molecules is discussed. Two excited singlet states (in the midst of four lowest states) have the charge-transfer character. These states have different charge-transfer contribution of the two electron donor groups to the same electron acceptor. In consequence, different conditions for the promotion of intramolecular proton transfer in excited state are created in each case.
9
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Fluorescence Spectra of Phenanthridine Isolated in the Supersonic Jet Expansion - An Ab Initio Analysis

81%
Deperasińska I., Prochorow J., Stepanenko Y.
Acta Physica Polonica A
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2005
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vol. 108
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issue 6
1005-1019
EN
Following the analysis of laser induced fluorescence spectrum of 7,8-benzoquinoline molecule, observed under conditions of isolation in the supersonic jet expansion, the ab initio analysis of laser induced fluorescence spectrum of phenanthridine, observed under the same experimental conditions, was performed. This analysis included: optimization of equilibrium geometry of phenanthridine in its first excited S_1 singlet state and computations of the frequencies of vibrational fundamental modes together with their geometry changes between the excited and the ground state. Comparison of the results of calculations with experimental data revealed their good agreement and an increase in the vibrational activity in the fluorescence spectrum in comparison to fluorescence spectrum of phenanthrene molecule (which is a parent aromatic hydrocarbon of phenanthridine and of 7,8-benzoquinoline). Such an increase in vibrational activity in the fluorescence spectrum was earlier observed also for 7,8-benzoquinoline molecule. Present analysis shows that this effect is due to molecular symmetry reduction caused by the substitution of nitrogen atom into the aromatic rings system of phenanthrene, as well as to the changes of equilibrium structure between the ground and excited states.
10
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Photoinduced Charge-Transfer Reactions of Tricyanoethlene with Aromatic Hydrocarbon Electron Donors. I. Emission Studies of Naphthalene-Tricyanoethylene Exciplex

62%
Dresner J., Kwapisz K., Deperasińska I., Prochorow J., Bruni P., Giardina A., Tosi G.
Acta Physica Polonica A
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2002
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vol. 102
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issue 3
443-468
EN
The fluorescence quenching of a series of aromatic hydrocarbon electron donors by an electron acceptor tricyanoethylene has been observed. The quenching mechanism is consistent with the charge-transfer (or electron-transfer) mechanism, as indicated by the appearance of a new, broad, and structureless exciplex emission band. Detailed, steady-state, and time-resolved emission studies of the kinetics and thermodynamics of exciplex formation and relaxation have been performed for naphthalene-tricyanoethylene system. It was found that the kinetics of monomer-exciplex equilibrium for this system, in a non-polar solvent (n-hexane), can be described in terms of a simple two-state photokinetic scheme. Within such a scheme, under conditions of the present experiment, napthalene-tricyanoethylene system approaches the limits under which exciplex formation is very effective - it becomes exclusively diffusion-controlled and at the same time a competitive process of thermal dissociation of exciplex ceases to operate. This leads to a very rarely observed reversal of physical meaning of the decay parameters which are describing the rise and the decay of exciplex fluorescence.
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