Naslov
Ultrafast Adiabatic Photodehydration of o-hydroxymethylphenol and Formation of Quinone Methide

Autori
Škalamera, Đani ; Antol, Ivana ; Mlinarić-Majerski, Kata ; Vančik, Hrvoj ; Phillips, David Lee ; Ma, Jiani ; Basarić, Nikola

Izvornik
Chemistry : a European journal (0947-6539) 2018 (2018), 24; 9426-9435

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
cryochemistry ; density functional calculations ; photochemistry ; quinone methides ; transient spectroscopy

Sažetak
Photochemical reactivity of 2-hydroxymethylphenol (1) has been investigated experimentally by photochemistry at cryogenic conditions and the detection of reactive intermediates by IR, and the nanosecond and femtosecond transient absorption spectroscopic methods in solutions at room temperature. In addition, theoretical studies were performed to facilitate the interpretation of the experimental results and also to simulate the reaction pathway for a better understanding of the reaction mechanism. The main finding of this work is that photodehydration of 1 takes place in an ultrafast adiabatic photochemical reaction without any obvious intermediate, delivering quinone methide (QM) in the excited state. Upon photoexcitation to a higher vibrational level of the singlet excited state, 1 undergoes vibrational relaxation leading to two photochemical pathways with one being the synchronous elimination of H2O to give a QM (2) in its S1 state and the other being a homolytic cleavage of the phenolic O-H bond to produce a phenoxyl radical (S0). Both are ultrafast processes that occur within a ps. The excited state of QM 2 (S1) probably deactivates to S0 via a conical intersection giving QM 2 (S0) and subsequently delivers benzoxete 4. Elucidation of the reaction mechanisms for the photodehydration of phenols where QMs are formed is important for the tuning the reactivity of QMs with DNA and proteins for potential applications of QMs in medicine as therapeutic agents.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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