Naslov
Short vs Long-Range Excited State Intramolecular Proton Transfer (ESIPT) Between Phenol OH and Aromatic Rings

Autori
Basarić, Nikola ; Wan, Peter

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Reactive Intermediates in Photochemistry / Bohne, Cornelia ; Durst, Tony ; Johnston, Linda ; Leigh, Willie - Ottawa, 2005

Skup
Reactive Intermediates in Photochemistry

Mjesto i datum
Ottawa, Kanada, 24.08.2005. - 26.08.2005

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
photochemistry; proton transfer; anthracenes; phenols; pyridines; quinone methides

Sažetak
Excited-state intramolcular proton transfer (ESIPT) is a fundamental photochemical process that has been studied extensively. ESIPT arises from changes of proton donating and accepting ability of appropriate functional groups upon excitation. Recently, we demonstrated that the increased acidity of the phenolic group in the excited-state can lead to the intramolecular proton transfer from phenol OH to nearby aromatic rings (protonation at carbon).[1-3] Thus, upon excitation of the 2-phenylphenol (1), the OH-proton is transferred to the positions 2’ and 4’ of the adjacent phenyl ring, giving quinone-methide intermediates. For the long-range proton transfer to the position 4’ the presence of water is necessary.[1] We report our continuing studies aimed at increasing control of the efficiency of both the short and long range ESIPT processes. In one project, we have replaced the adjacent phenyl ring with a pyridine ring (4). In this system, proton transfer was observed to both 2’ and 4’ positions with enhanced transfer to the 4’ position on addition of water. LFP studies showed the formation of both quinone methides 5 and 6. Phenol-anthracene systems also undergo ESIPT.[3] In continuing studies here, we have found that a simple 10-methyl derivative (7) reacts via proton transfer to both 9 and 10-positions of the anthracene ring both requiring the presence of water, giving rise a quinone methide intermediate (8) and a zwitterion (9). Both are trapped by nucleophiles furnishing dihydro-anthracene products with nucleophile being added to the anthracene moiety. [1] M. Lukeman and P. Wan, J. Am. Chem. Soc., 2002, 124, 9458-9464. [2] M. Lukeman and P. Wan, J. Am. Chem. Soc., 2003, 125, 1164-1165. [3] M. Flegel, M. Lukeman, L. Huck and P. Wan, J. Am. Chem. Soc., 2004, 126, 7890-7897.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA