Regioselective trans-cis photoisomerization of m-styrylstilbenes

Journal Article · Wed Jan 06 04:00:00 EST 1988 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00209a031· OSTI ID:7004335

Ito, Y; Uozy, Y; Dote, T; Ueda, M; Matsuura, T

Trans-cis photoisomerization of m-styrylstilbenes, i.e., 2,4,6-triisopropyl-3'-styrylstilbene (TISS), 2,4,6-trimethyl-3'-styrylstilbene (TMSS), and 3-styrylstilbene (SS), and of stilbenes, i.e., 2,4,6-triisopropylstilbene (TIS), 2,4,6-trimethylstilbene (TMS), and stilbene (S), are studied under direct of benzophenone-sensitized irradiation in hexane. Measurements of quantum yields of isomerization have revealed that although the styrylstilbene molecule bears two styryl groups, the reaction is highly regioselective, depending upon the excitation conditions and reactant structures. For example, isomerization of trans, trans-TISS and trans,cis-TISS occurred either at the 2,4,6-trisubstituted styryl side upon direct excitation or at the unstubstituted styryl side upon sensitized excitation. When the starting material carries an unsubstituted cis-styryl group, the major isomerization always occurred at this moiety by either direct or sensitized excitation, e.g., cis,trans-TISS ..-->.. trans,trans-TISS, cis,cis-TISS ..-->.. trans,cis-TISS, and cis,trans-SS ..-->.. trans,trans-SS. Furthermore, the photoisomerization of cis,cis-SS was found to be one-way. These results are interpreted in terms of the usual energy sink concept: the excited-state energies (E/sub S/ and E/sub T/) of the stilbene chromophores depend on molecular distortion in a subtle manner.

• Research Organization: Kyoto Univ. (Japan)
• OSTI ID: 7004335
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 110:1; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ABSORPTION SPECTROSCOPY
AROMATICS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DE-EXCITATION
EFFICIENCY
ENERGY LEVELS
ENERGY TRANSFER
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
ISOMERIZATION
MAGNETIC RESONANCE
MULTIPLETS
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOCHEMISTRY
QUANTUM EFFICIENCY
RADIATIONLESS DECAY
RESONANCE
SPECTRA
SPECTROSCOPY
STILBENE
TRIPLETS