64980-69-4Relevant academic research and scientific papers
Photophysics, Photochemistry, and Kinetics of Photochromic Fulgides
Lenoble, Christian,Becker, Ralph S.
, p. 2651 - 2654 (1986)
Nine different substituted bismethylene succinic anhydrides (fulgides) have been examined by microsecond and nanosecond laser flash techniques.In addition, fluorescence lifetimes have been determined for some fulgides.No triplet transients have been observed and oxygen (vs. nitrogen) has no effect on the spectra, or the kinetics of formation (400 μs) of the colored photoproduct.The relative quantum yield of photocoloration of one fulgide is observed to significantly increase with shorter wavelength excitation (266 nm) vs. longer wavelength (355 nm).This is discussed and considered in terms of earlier observations of a decrease in the quantum yield of fluorescence with increasing energy of excitation.All data strongly suggest that an excited singlet state of ?,?* character is the originating state for photochorism/photochemistry.
Direct and Sensitized Photoisomerization of α, δ- Phenylfulgides
Ilge, H.-D.,Paetzold, R.
, p. 705 - 720 (2007/10/02)
The photoreactions starting from the E- and E-E-isomers of mono-, di-, tri- and tetra-(substituted-)phenylfulgides are investigated.The phenylfulgides show strong steric interactions in the molecular framework.For that reason internal conversion is the main deactivation process which increases in the series of mono-, tri- and tetraphenylfulgides.The α, δ-di-(substituted-)-phenylfulgides show the highest photoreactivity.At room temperature in no case luminescence is observed from any E(E-E)-, Z(E-Z, Z-E)- or Z-Z-phenylfulgid isomer of the substances under study.Intersystem crossing cannot compete neither with thermal deactivation nor can it be observed by applying both the internal and external heavy atom effect.The phenylfulgides show typical ??*-photoreactivity: in the singlet state E-Z-isomerization about one double bond competes with electrocyclic ring closure; in the triplet state only simultaneous E-Z-isomerization about the two double bonds is observed.The steric and electronic substituent influences on the photoreactivity are interpreted.A first qualitative model of the isomerization reactions of the fulgides in the excited states is established.
