Present Status of the Photoisomerization About Ethylenic Bonds

Donor-Acceptor Conjugated Linear Polyenes: A Study of Excited State Intramolecular Charge Transfer, Photoisomerization and Fluorescence Probe Properties

“…The Fig. 4 Chemical structure of donor-acceptor ethenylindoles (11)(12)(13)(14)(15). Compounds 12-13 fluoresce from CRICT state.…”

“…[6][7][8][9][10]. In order to understand the exact nature of the electronically excited state properties of linear polyenes, donor-acceptor molecules based on α,ω-diphenylpolyene [Ar(CH = CH) n Ar] framework, like 1,2-diphenylethene [Ar(CH = CH)Ar, DPE, stilbene], 1,4-diphenylbutadiene [Ar(CH = CH) 2 Ar, DPB], 1,6-diphenylhexatriene [Ar(CH = CH) 3 Ar, DPH] and other longer homologues have been extensively studied as models of photobiologically significant linear polyenes like retinal, carotenoids and their lower homologues [11][12][13][14][15][16][17][18][19][20]. In contrast to the non-fluorescent retinyl polyenes, the fluorescent nature of model α,ω-diphenylpolyenes facilitates study of the electronically excited state properties of linear polyenes.…”

Photochemistry Meets Natural‐Product Synthesis

“…In the transition to 1 0 [ethylene], reversion to the planar atomic arrangement takes place. Discussion about the 'Present Status of the Photoisomerization about Ethylenic Bonds' [18], still incessant even today, is a good example of how an increasing number of individual cases makes it all the more difficult to propose a comprehensive mechanistic picture. Discussion about the 'Present Status of the Photoisomerization about Ethylenic Bonds' [18], still incessant even today, is a good example of how an increasing number of individual cases makes it all the more difficult to propose a comprehensive mechanistic picture.…”

“…The chemical yield of 5 after MPLC at 0°was 66%. A second possible cause of wavelength dependency in the composition of a photoproduct (P 1 + P 2 ) is selective light absorption of two coexisting conformers E 1 and E 2 in the photo-educt (Scheme 7) 18 ). The case study of the preparation of vitamin D (7) with the aid of electrocyclic ring cleavage of provitamin D (1) to previtamin D (5) (Scheme 3) makes it clear that a change in the wavelength of excitatory light may be able to influence the composition of the many-component photoproduct.…”

UV/VIS spectral properties of novel natural products from Turkish lichens

“…The second possibility seems less probable: fast rotation around double bond is usually linked with ethylenelike cis-trans photoisomerisation [26], but, according to experimental results for compound 3, no spectral changes were noticed after a long-time irradiation with the use of UV/VIS lamp (the light source of Jasco spectrophotometer).…”