SPECTRAL AND BASIC PROPERTIES OF FLAVONES IN THE GROUND AND EXCITED STATES
UDC 547.814.5 + 54.04
Keywords:
flavones, electronic spectroscopy, acid-base properties, protolytic equilibriaAbstract
Dependence between structures of R-oxyflavones and their spectral and basic properties has been investigated. It was found that pKa of flavones, depending on positions of hydroxy and methoxy groups, increase by 6-8 orders of magnitude upon excitation and reaches 3.7-6.6 units. Due to high pKa* value carbonyl group can serve as a proton acceptor in the excited-state intramolecular proton transfer as well as in the formation of phototautomers of 7- and 4'-hydroxyflavones in protic solvents.
References
1. Sengupta P.K. Excited state proton-transfer spectroscopy of
3-hydroxyflavone and quercetin / P.K. Sengupta, M. Kasha // Chem. Phys. Lett. – 1979. – V. 68. – P. 382–385.
2. Roshal A.D. Tuning the mechanism of proton-transfer in a hydroxyflavone derivative / A.D. Roshal, J.A. Organero, A. Douhal // Chem. Phys. Lett. – 2003. – V. 379. – P. 53–59.
3. McMorrow D. Intramolecular Excited-State Proton Transfer in
3-hydroxyflavone. Hydrogen-bonding solvent perturbations / D. McMorrow, M. Kasha // J. Phys. Chem. – 1984. – V. 88, № 11. – P. 2235–2243.
4. Parthenopoulos D.A. Ground state anion formation and picosecond excitation dynamics of 3-hydroxyflavone in formamide / D.A. Parthenopoulos, M. Kasha // Chem. Phys. Lett. – 1990. – V. 173, № 4. – P. 303–309.
5. Pogodaeva N.N. Ultraviolet absorption of flavonoids IV. Protonation constants of some monohydroxy flavones / N.N. Pogodaeva, N.A. Tyukavkina // Khim. Prirod. Soed. – 1972. – № 1. – P. 22–24.
6. Pogodaeva N.N. Ultraviolet absorption of flavonoids VI. Protonation constants of some dihydroxyflavones / N.N. Pogodaeva, N.A. Tyukavkina // Khim. Prirod. Soed. – 1975. – № 5. – P. 587–590.
7. Roshal A.D. Spectral and acid-base features of 3,7-dihydroxy-2,8-diphenyl-4h,6h-pyrano[3,2-g]chromene-4,6-dione (diflavonol) – a potential probe for monitoring the properties of liquid phases / A.D. Roshal, V. I. Moroz, V. G. Pivova¬renko, et al. // J. Org. Chem. – 2003. - V. 68, № 15. – P. 5860–5869.
8. Svechkarev D.A. Nature of dual fluorescence in 2-(quinolin-2-yl)-3-hydroxychromone: Tuning between concurrent H-bond directions and ESIPT pathways / D.A. Svechkarev, A.O. Doroshenko, V.N. Baumer, et al. // J. Lumin. – 2011. – V. 131, № 2. – P. 253–261.
9. Roshal A.D. Flavonols as metal-ion chelators: Complex formation with Mg2+ and Ba2+ cations in the excited state / A.D. Roshal, A.V. Grigorovich, A.O. Do¬rochenko, et al. // J. Photochem. Photobiol. A. – 1999. – V. 127, № 1-3. – P. 89–100.
10. Shan M. De novo asymmetric syntheses of SL0101 and its analogues via a palladium-catalyzed glycosylation / M. Shan, G.A. O'Doherty // Org. Lett. – 2006. – V. 8, № 22. – P. 5149–5152.
Downloads
Published
Issue
Section
License
Copyright (c) 2014 A. Varenikov, mgr, I. Serdiuk, PhD student, A. Roshal, Dr. hab.
This work is licensed under a Creative Commons Attribution 4.0 International License.
