fulltext.study @t Gmail

Photophysical properties of halo-derivatives of angelicins

Paper ID Volume ID Publish Year Pages File Format Full-Text
28662 44084 2008 8 PDF Available
Title
Photophysical properties of halo-derivatives of angelicins
Abstract

The properties of the lowest excited singlet and triplet state of four halo-angelicins (HA) have been investigated by steady-state and time-resolved spectrometric techniques. The study has been performed in solvents with different polarity and proticity: cyclohexane, dioxane, acetonitrile, ethanol and 2,2,2-trifluoroethanol. Absorption and emission spectra showed that the nature of lowest singlet state is mainly π,π* and the transitions are allowed or partially allowed. Absorption coefficients, fluorescence quantum efficiency and lifetimes are also presented. Flash photolysis investigations have indicated the presence of a unique transient assignable to the lowest triplet state T1. The triplet state has been characterized in terms of absorption spectra, decay kinetics, molar absorption coefficients and formation quantum yields. The racing of both intersystem crossing and fluorescence quantum yields going from a non-polar to a highly polar-protic solvent indicates the presence of a S2 state, n,π* in nature, close lying to the π,π* one. The quantum yields of the singlet decay pathways (fluorescence, intersystem crossing and internal conversion) depends markedly on the energy gap between S1 and S2 states in agreement with the manifestation of the “proximity effect”. In fact in cyclohexane HA decay mainly through S1 → S0 internal conversion, while in trifluoroethanol their fluorescence and intersystem crossing increase significantly.Singlet-oxygen quantum yields have been also determined in order to understand the possible application of the investigated drugs in photodynamic therapy. The absence of photochemical pathways allowed the indirect evaluation of the internal conversion decay bringing to the achievement of a complete decay pathways picture.

Keywords
Angelicins; Fluorescence; Proximity effect; Singlet oxygen; Triplet state; Photodynamic therapy
First Page Preview
Photophysical properties of halo-derivatives of angelicins
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 198, Issue 1, 5 July 2008, Pages 98–105
Authors
, , , , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us