Charge transfer and cis-trans photoisomerization

Journal Article · Thu Jul 13 04:00:00 EDT 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100351a027· OSTI ID:6972073

Ebbesen, T W; Tokumaru, K ^[1]; Sumitani, M; Yoshihara, K ^[2]

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1. Univ. of Tsukuba, Ibaraki (Japan)
2. Institute for Molecular Science, Okazaki (Japan)

The photophysical and photochemical properties of cis- and trans-1,2-bis(1-methyl-4-pyridinio)ethylene dication in acetonitrile are examined. These properties are significantly altered by the charge-transfer complexation in the ground state. The free olefins undergo cis-trans photoisomerization with a quantum yield of ca. 0.3. The cis isomer does not fluoresce unlike the trans isomer ({phi}{sub F} = 0.01, {tau}{sub F} = 5 {times} 10{sup {minus}11} s). The fluorescence of the trans isomer is quenched by complexation with iodide ions in the ground state. In addition, static quenching occurs within a 16-{angstrom} radius. The constants of the CT complexation with the iodide ion (in the ground state) are 1.6 M{sup {minus}1} for cis and 4.6 M{sup {minus}1} for trans. Upon excitation in the charge-transfer absorption band, the trans iodide complex gives the trans radical with a quantum yield of 0.06. The cis iodide complex leads not only to the formation of the cis radical isomer with a quantum yield of 0.02 but also to the trans isomer dication (quantum yield 0.05). The latter reaction can be interpreted either as a germinate pair catalyzed event or as isomerization in the excited charge-transfer state from the results of the nanosecond and picosecond laser flash photolysis experiments.

• OSTI ID: 6972073
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:14; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400000* -- Chemistry
400500 -- Photochemistry
ALKENES
CHARGE TRANSPORT
CHEMICAL REACTIONS
CHEMISTRY
DATA
DATA ANALYSIS
ENERGY LEVELS
ETHYLENE
EXCITED STATES
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
ISOMERIZATION
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHOTOCHEMISTRY