Ab Initio MR-CISD Study of Gas-Phase Basicity of Formamide in the First Excited Singlet State

2004 ◽  
Vol 108 (46) ◽  
pp. 10317-10325 ◽  
Author(s):  
Ivana Antol ◽  
Mirjana Eckert-Maksic ◽  
Hans Lischka
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Singlet State ◽  
Excited Singlet State ◽  
Excited Singlet

The Excited Singlet State of Chloropentafluoroacetone; Quenching by Unsaturated Hydrocarbons

1971 ◽  
Vol 49 (12) ◽  
pp. 2053-2058 ◽  
Author(s):  
H. S. Samant ◽  
A. J. Yarwood
Keyword(s):  
Gas Phase ◽  
Singlet State ◽  
Excited Singlet State ◽  
Energy Relation ◽  
Excited Singlet ◽  
Quenching Rate ◽  
Unsaturated Hydrocarbons ◽  
Linear Free Energy ◽  
Free Energy Relation ◽  
A Charge

The fluorescence of chloropentafluoroacetone in the gas phase at 23 °C is quenched by the addition of certain olefins. The quenching rate constants of 17 unsaturated hydrocarbons for the first excited singlet state of chloropentafluoroacetone are reported. The molecules are divided into two classes on the basis of their quenching abilities, (a) olefins with only electron-withdrawing substituents and (b) olefins with electron-donating substituents. It is shown that the quenching by molecules in the latter group can be quantitatively correlated with the ionization potential (i.p.) of the quenching molecule. The relation is log k = 18.0 − 0.79 (i.p.), i.e. a type of linear free energy relation is obeyed. This implies that the quenching by molecules containing only electron-donating substituents involves a charge-transfer complex.

Quenching of Fluorescence of Chloropentafluoroacetone by Saturated Hydrocarbons

1972 ◽  
Vol 50 (9) ◽  
pp. 1429-1432 ◽  
Author(s):  
A. J. Yarwood
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Singlet State ◽  
Fluorescence Yield ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Quenching Rate ◽  
Saturated Hydrocarbons ◽  
Phase Measurements ◽  
Electronically Excited

Saturated hydrocarbons can quench the electronically excited singlet state of a simple ketone in the gas phase. Measurements on the quenching of the fluorescence yield of chloropentafluoroacetone at 23 °C show that different saturated hydrocarbons can deactivate the excited singlet state with varying efficiencies. The quenching rate constants are reported and possible relationships considered.

Ab initio insights into the mechanism of excited-state intramolecular proton transfer triggered by the second excited singlet state of a fluorescent dye: an anti-Kasha behavior

2019 ◽  
Vol 3 (6) ◽  
pp. 1225-1230 ◽  
Author(s):  
Huijuan Yuan ◽  
Xugeng Guo ◽  
Jinglai Zhang
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Ab Initio ◽  
Singlet State ◽  
Intramolecular Proton Transfer ◽  
Fluorescent Dye ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Ultrafast Process

An excited-state intramolecular proton transfer (ESIPT) reaction triggered by the second excited singlet S2 state is found by ab initio calculations to be an ultrafast process for a novel fluorophore.

Theoretical and Experimental Dipole Moments of Purines

2002 ◽  
Vol 67 (8) ◽  
pp. 1109-1124 ◽  
Author(s):  
Cyril Párkányi ◽  
Christian Boniface ◽  
Jean-Jacques Aaron ◽  
Mihaela Bulaceanu-MacNair ◽  
Marwan Dakkouri
Keyword(s):  
Ab Initio ◽  
Ground State ◽  
Singlet State ◽  
Dipole Moments ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Solvatochromic Shift ◽  
Experimental Values ◽  
Vector Sum ◽  
Ground State Dipole Moments

As a follow-up on our previous study of a series of purines (purine, 6-chloropurine, purine-6-thiol, hypoxanthine, theobromine, theophylline, caffeine, and uric acid), we have investigated six additional biologically important purines (adenine, guanine, isoguanine, thioguanine, xanthine, and kinetin). Their ground-state dipole moments were measured in dioxane at 293 K. The first excited singlet-state dipole moments were obtained using the solvatochromic shift equations (McRae, Suppan, Bakhshiev, and Kawski-Chamma-Viallet). The theoretical dipole moments were calculated as a combination of the π-moment (PPP method) and the σ-moment (vector sum of the σ-bond and σ-group moments). The same approach was used to obtain their first excited singlet-state dipole moments (excited state π-moment; σ-moment assumed to be the same as in the ground state). Ab initio HF 6-31G** calculations were also used to obtain ground-state dipole moments for all the fourteen purines under study. In addition, a DFT/B3PW91/6311++(2df,2p) calculation has been carried out for purine for comparison. The different sets of theoretical dipole moments were compared with the respective experimental values. There is an approximately equally good agreement among the experimental dipole moments and the PPP + σ dipole moments (±6.9%) and the ab initio dipole moments (±7.4%). The effect of structure on the dipole moments is discussed.

The Gold Porphyrin First Excited Singlet State¶

2002 ◽  
Vol 76 (1) ◽  
pp. 47 ◽  
Author(s):  
Joakim Andréasson ◽  
Gerdenis Kodis ◽  
Su Lin ◽  
Ana L. Moore ◽  
Thomas A. Moore ◽  
...  
Keyword(s):  
Singlet State ◽  
Excited Singlet State ◽  
Excited Singlet
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