Direct and sensitized photoisomerization of 1,4-diphenylbutadienes

Journal Article · Tue Mar 29 23:00:00 EST 1988 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00215a027· OSTI ID:6974438

Yee, W A; Hug, S J; Kliger, D S

Photoisomerization of the three stereoisomers of 1,4-diphenylbutadiene (DPB) in room-temperature cyclohexane solution was studied by direct excitation and by triplet sensitization. The photostationary mixtures in both singlet and triplet experiments contain only tran,trans and cis,trans isomers; no cis,cis isomer or any photoproducts were observed. The two cis isomers exhibit no measurable fluorescence or triplet formation. Results are interpreted in terms of allylmethylene-like intermediates. Efficient internal conversion of singlet DPBs is inferred from low isomerization quantum yields by direct excitation. Triplet-sensitized isomerizations show a marked DPB concentration dependence of photostationary composition and quantum yields. Analysis of these data reveals a quantum chain process involving excited triplet DPB as the chain-carrying species. Transient absorption measurements show that sensitized excitation of any DPB isomer leads directly to a fast equilibrium between triplet all-trans and trans-twisted forms.

• Research Organization: Santa Clara Univ., CA (USA)
• OSTI ID: 6974438
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 110:7; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ABSORPTION SPECTROSCOPY
ALKANES
AROMATICS
BUTADIENE
CHEMICAL REACTIONS
CHEMISTRY
CYCLOALKANES
CYCLOHEXANE
DATA
DIENES
EFFICIENCY
ENERGY LEVELS
EXCITED STATES
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
ISOMERIZATION
ISOMERS
MEDIUM TEMPERATURE
MULTIPLETS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
POLYENES
QUANTUM EFFICIENCY
SPECTROSCOPY
TRIPLETS