Anti-Kasha Behavior of 3-Hydroxyflavone and Its Derivatives

Autor: David Lee Phillips, Hoi Ling Luk, Ka Wa Fan
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: International Journal of Molecular Sciences
Volume 22
Issue 20
International Journal of Molecular Sciences, Vol 22, Iss 11103, p 11103 (2021)
ISSN: 1422-0067
DOI: 10.3390/ijms222011103
Popis: Excited state intramolecular proton transfer (ESIPT) in 3-hydroxyflavone (3HF) has been known for its dependence on excitation wavelength. Such a behavior violates Kasha’s rule, which states that the emission and photochemistry of a compound would only take place from its lowest excited state. The photochemistry of 3HF was studied using femtosecond transient absorption spectroscopy at a shorter wavelength excitation (266 nm), and these new experimental findings were interpreted with the aid of computational studies. These new results were compared with those from previous studies that were obtained with a longer wavelength excitation and show that there exists a pathway of proton transfer that bypasses the normal first excited state from the higher excited state to the tautomer from first excited state. The experimental data correlate with the electron density difference calculations such that the proton transfer process is faster on the longer excitation wavelength than compared to the shorter excitation wavelength.
Databáze: OpenAIRE