Polar substituents in barrelene photochemistry: mechanistic aspects of the photochemistry of 2-cyanobenzobarrelene

1978 ◽  
Vol 56 (23) ◽  
pp. 3027-3037 ◽  
Author(s):  
Christopher Owen Bender ◽  
Dee W. Brooks ◽  
William Cheng ◽  
Douglas Dolman ◽  
Seamus F. O'Shea ◽  
...  
Keyword(s):  
Excited States ◽  
Interaction Energies ◽  
Direct Photolysis ◽  
Deuterium Labelling ◽  
Atom Interaction ◽  
Polar Substituents ◽  
Triplet Excited States ◽  
Ci Calculations

The direct photolysis of 2-cyanobenzobarrelene (4) yields 5- and 7-cyanobenzocyclooctatetraene [Formula: see text] and 1-cyanobenzosemibullvalene [Formula: see text], whereas the acetophenone sensitized irradiation of 4 yields only 8 [Formula: see text]. Deuterium labelling studies suggest that 7 derives from an initial 2Π + 2Π cycloaddition between the vinyl and vinylcyano bridges of 4, whereas 8, resulting from direct or sensitized irradiations of 4, derives from di-Π-methane rearrangement involving initial vinyl–vinylcyano bridging. The observed initial bonding preferences of the 2Π + 2Π cycloadditions and di-Π-methane rearrangement of 4 are in accord with predictions based upon CNDO-CI calculations of changes in atom–atom interaction energies between possible bridging sites in singlet and triplet excited states of 4.

Mechanistic and theoretical studies of the photochemistry of 5,6-dihydro-2-cyanobenzobarrelene

1979 ◽  
Vol 57 (21) ◽  
pp. 2804-2811 ◽  
Author(s):  
Christopher Owen Bender ◽  
Seamus F. O'Shea
Keyword(s):  
Excited States ◽  
Theoretical Studies ◽  
Interaction Energies ◽  
Deuterium Labelling ◽  
Atom Interaction ◽  
Ci Calculations

The direct (Φ6 = 0.04) or acetone sensitized (Φ6 = 0.51) photolysis of 2-cyano-1,4-dihydro-1,4-ethanonaphthalene (5) yields 1-cyanobenzotricyclo[3.3.0.02,8]octa-3-ene (6). Deuterium labelling studies suggest that 6 derives from a Zimmerman di-π-methane rearrangement and not from the McCullough 1-cyanocyclohexene rearrangement. The observed rearrangement and regioselectivity are in accord with predictions based upon CNDO-CI calculations of changes in atom–atom interaction energies on excitation to the S1 and T1 excited states of 5.

Substituent effects in arosemibullvalene photochemistry: the methylcyclopropane rearrangement of 1,8-dimethylbenzosemibullvalene

1982 ◽  
Vol 60 (15) ◽  
pp. 1942-1952 ◽  
Author(s):  
Christopher Owen Bender ◽  
Donald Laverne Bengtson ◽  
Douglas Dolman ◽  
Carolyn Elaine L. Herle ◽  
Seamus Francis O'Shea
Keyword(s):  
Gas Phase ◽  
Excited States ◽  
Substituent Effects ◽  
Interaction Energies ◽  
Direct Irradiation ◽  
Atom Interaction ◽  
Ci Calculations

1,6- and 1,8-Dimethylbenzotricyclo[3.3.0.02,8]octa-3,6-diene (16 and 14) are the major semibullvalene products formed from acetophenone sensitized irradiations of the barrelenes 2,6- and 2,3-dimethyl-1,4-dihydro-1,4-ethenonaphthalene (37 and 22), respectively (Φ37→16 = 0.65; Φ22→14=0.57). The direct (Φ14 = 0.017) or chlorobenzene sensitized (Φ14 = 0.12) irradiation of 14 yields 2,3-benzo-5-methyl-6-methylenebicyclo[3.3.0]octa-2,7-diene (17), a transformation typical of methylcyclopropanes. Gas phase thermolysis (420 °C/6 Torr) of 14 gives 6,7-dimethylbenzocyclooctatetraene (15). The direct irradiation (Φ39 = 0.003) or the gas phase thermolysis (395 °C/6 Torr) of 16 gives 6,9-dimethylbenzocyclooctatetraene (39). The rearrangement 14 → 17 is in accord with predictions based upon CNDO-CI calculations of changes in atom–atom interaction energies on excitation to the S1 or T1 excited states of 14.

SAC-CI and full-CI calculations for the singlet and triplet excited states of H2O

1991 ◽  
Vol 179 (5-6) ◽  
pp. 555-558 ◽  
Author(s):  
Hiroshi Nakatsuji ◽  
Kimihiko Hirao ◽  
Yoshihiro Mizukami
Keyword(s):  
Excited States ◽  
Full Ci ◽  
Triplet Excited States ◽  
Ci Calculations

Unconventional singlet fission materials

2021 ◽  
Author(s):  
Tobias Ullrich ◽  
Dominik Munz ◽  
Dirk M. Guldi
Keyword(s):  
Excited States ◽  
Singlet Fission ◽  
Triplet Excited States

Singlet fission (SF) is a photophysical downconversion pathway, in which a singlet excitation transforms into two triplet excited states.

Different Quenching Effect of Intramolecular Rotation on the Singlet and Triplet Excited States of Bodipy

2017 ◽  
Vol 122 (1) ◽  
pp. 185-193 ◽  
Author(s):  
Zhangrong Lou ◽  
Yuqi Hou ◽  
Kepeng Chen ◽  
Jianzhang Zhao ◽  
Shaomin Ji ◽  
...  
Keyword(s):  
Excited States ◽  
Quenching Effect ◽  
Triplet Excited States ◽  
Intramolecular Rotation

Study of the triplet excited states and DFT calculations of iridium(III) complexes with mixed ligands

2018 ◽  
Vol 1164 ◽  
pp. 164-171
Author(s):  
Naokazu Yoshikawa ◽  
Shoko Yamazaki ◽  
Natsumi Kato ◽  
Nobuko Kanehisa ◽  
Tsuyoshi Inoue ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Excited States ◽  
Mixed Ligands ◽  
Triplet Excited States
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