75102-19-1Relevant academic research and scientific papers
NMR Spectra and Configuration of Bichromophoric Compounds with Norbornylogue Spacer
Touillaux, R.,Jiwan, J.-L. Habib,Soumillion, J.-Ph.
, p. 184 - 185 (1994)
The determination of the structure and configuration of bichromophoric compounds with a norbornylogue spacer is presented on the basis of the 1H and 13C chemical shifts and vicinal H-H coupling constants. - Keywords: 1H NMR 13C NMR Bichromophoric compounds Norbornylogue spacer
Photoinduced Charge Separation in Rigid Bichromophoric Compounds and Charge Transfer State Electron Transfer Reactivity
Jiwan, J. L. Habib,Soumillion, J. Ph.
, p. 14223 - 14230 (2007/10/02)
Bichromophoric compounds giving, after photoexcitation, a locally excited state (LE) rapidly followed by an intramolecular charge transfer (CT) state were designed using a Paddon-Row type synthesis.The electron-accepting end of the CT state is chosen in order to play the role of an electron relay versus external acceptors.In this way, electron transfer photosensitization is made available by using the CT state of bichromophores.The photophysics of the synthesized bichromophores is discussed, and the reductive dechlorination of polychlorinated benzenes is used as a test reaction.The bichromophoric sensitizer is unexpectedly found to be totally regenerated: the reaction is shown to be initiated by an electron transfer from the CT state to the chlorinated quencher.A rapidly breaking radical anion leads to the dechlorination, while the recombination of the sensitizer radical cation with the released chloride anion opens the way to the sensitizer recovery.
Electronic Control of Stereoselectivity. 6. Directionality of Singlet Oxygen Addition to 1,4-Dimethoxynaphthalenes Laterally Fused to Bridged Bicyclic Systems
Paquette, Leo A.,Bellamy, Francois,Boehm, Michael C.,Gleiter, Rolf
, p. 4913 - 4921 (2007/10/02)
The photooxygenation in methanol solution of 1,4-dimethoxynaphthalene derivatives having bridged bicyclic systems fused at C2, C3 with rose bengal as sensitizer leads to formation of stereoisomeric epoxynaphthoquinone monoketals.These products, which are readily hydrolyzed in acid solution to the epoxynaphthoquinones, possess an epoxide oxygen which serves as a stereochemical marker for the directionality of singlet oxygen addition.For the norbornyl and norbornenyl cases, endo bonding by 1O2 is preferred; the reverse is true for the pair of bicyclooctenyl derivatives studied.This contrasting stereoselection was compared to the stereochemical consequences of alkaline hydroperoxidation of the corresponding naphthoquinones.In each instance, the reaction course was opposite to that observed with singlet oxygenation.Both processes are analyzed from the theoretical viewpoint, use being made of the photoelectron spectra of the substrate molecules, detailed evaluation of frontier orbital effects, and prevailing ?/? interactions.While the alkaline hydroperoxidation results can be interpreted in terms of standard kinetic and steric control, an understanding of the directionality of 1O2 capture appears dependent on our appreciation of the contributions made by the ? electrons of the bicyclic moieties upon the aromatic ? orbitals.The tilting caused by such interactions is thought to be source of the experimentally observed exo/endo ratios.
