Analytic energy derivative methods for excited singlet states of the same symmetry as the electronic ground state

1985 ◽  
Vol 83 (3) ◽  
pp. 1162-1167 ◽  
Author(s):  
George Fitzgerald ◽  
Henry F. Schaefer
Keyword(s):  
Ground State ◽  
Electronic Ground State ◽  
Excited Singlet ◽  
Singlet States ◽  
Excited Singlet States ◽  
Electronic Ground

The photochemistry of indenyl alcohols and esters: Substituent effects on the competition between ion- and radical-derived products

2003 ◽  
Vol 81 (10) ◽  
pp. 1083-1095 ◽  
Author(s):  
J A Pincock ◽  
I S Young
Keyword(s):  
Excited State ◽  
Ground State ◽  
Fluorescence Emission ◽  
Substituent Effects ◽  
Sharp Contrast ◽  
Carboxylate Anion ◽  
Excited Singlet ◽  
Heterolytic Cleavage ◽  
Singlet States ◽  
Excited Singlet States

The photochemistry of the indenyl acetates 1 and pivalates 2, substituted with X = H, 5-CH3O, and 6-CH3O, have been examined in both methanol and cyclohexane. The precursor alcohols 3 were also found to be photoreactive. Although only radical-derived products were obtained in cyclohexane, both ion- and radical-derived products were formed in methanol. The absence of significant fluorescence emission from any of the substrates 1, 2, and 3 indicates that the excited singlet states are highly reactive. A mechanism is proposed for the ion-derived products that proceeds through direct heterolytic cleavage to give an indenyl cation – carboxylate anion pair. The indenyl cations generated are anti-aromatic in the ground state and their efficient generation by this photochemical solvolysis is in sharp contrast to the very low reactivity of related ground-state substrates. For the pivalate esters 2, an excited-state migratory decarboxylation is proposed for the formation of tert-butyl derived products.Key words: ester photochemistry, indenyl cations, indenyl radicals.

scholarly journals Elektronendelokalisierung im Grundzustand und in angeregten Zustanden / Electron Derealization in the Ground State and in Excited States

1977 ◽  
Vol 32 (2) ◽  
pp. 178-181 ◽  
Author(s):  
F. Fratev ◽  
W. Monev ◽  
O. E. Polansky ◽  
S. Stojanov ◽  
N. Tyutyulkov
Keyword(s):  
Excited States ◽  
Ground State ◽  
Excited Singlet ◽  
Singlet States ◽  
Excited Singlet States

The dependence of the fluorescence ability on the derealization of electrons in excited singlet states is discussed. It is shown that mainly those states fluoresce in which the electrons are most delocalized. The derealization can be described by Julg's Parameter A

scholarly journals The Ugi four-component reaction as a concise modular synthetic tool for photo-induced electron transfer donor-anthraquinone dyads

2014 ◽  
Vol 10 ◽  
pp. 1006-1016 ◽  
Author(s):  
Sarah Bay ◽  
Gamall Makhloufi ◽  
Christoph Janiak ◽  
Thomas J J Müller
Keyword(s):  
Electron Transfer ◽  
Excited Singlet ◽  
Gibbs Energies ◽  
Singlet States ◽  
Vis Spectroscopy ◽  
Donor Acceptor ◽  
Photo Induced Electron Transfer ◽  
Excited Singlet States ◽  
A Charge ◽  
Electronic Ground

Phenothiazinyl and carbazolyl-donor moieties can be covalently coupled to an anthraquinone acceptor unit through an Ugi four-component reaction in a rapid, highly convergent fashion and with moderate to good yields. These novel donor–acceptor dyads are electronically decoupled in the electronic ground state according to UV–vis spectroscopy and cyclic voltammetry. However, in the excited state the inherent donor luminescence is efficiently quenched. Previously performed femtosecond spectroscopic measurements account for a rapid exergonic depopulation of the excited singlet states into a charge-separated state. Calculations of the Gibbs energy of photo-induced electron transfer from readily available UV–vis spectroscopic and cyclovoltammetric data applying the Weller approximation enables a quick evaluation of these novel donor–acceptor dyads. In addition, the X-ray structure of a phenothiazinyl–anthraquinone dyad supports short donor–acceptor distances by an intramolecular π-stacking conformation, an important assumption also implied in the calculations of the Gibbs energies according to the Weller approximation.

Haloalkane-Aromatic Complexes in the Ground and Excited States Molecular Orbital Calculation

1980 ◽  
Vol 35 (4) ◽  
pp. 418-422 ◽  
Author(s):  
I. M. Brinn
Keyword(s):  
Molecular Orbital ◽  
Excited States ◽  
Ground State ◽  
Substituent Effect ◽  
Molecular Orbital Calculation ◽  
Complex Stability ◽  
Excited Singlet ◽  
Singlet States ◽  
Aromatic Complexes ◽  
Excited Singlet States

Abstract CNDO/2 calculations have been carried out on a series of haloalkane-aromatic 1: 1 complexes in the ground and first excited singlet states and one 2 : 1 complex in the ground state. Calculated stabilities agree very well with reported experimental results for the ground state. Our calculations indicate that the substituent effect on complex stability in excited states will be the opposite of that found for the ground state.

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