Photophysical properties of 2-Phenylindole in poly (vinyl alcohol) film at room temperature. Enhanced phosphorescence anisotropy with direct triplet state excitation.

Autor: Gryczynski Z; Department of Microbiology, Immunology and Genetics, Center for Fluorescence Technologies and Nanomedicine, University of North Texas Health Science Center, Fort Worth, TX 76107, United States of America. Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX 76129, United States of America., Kimball J, Fudala R, Chavez J, Ceresa L, Szabelski M, Borejdo J, Gryczynski I
Jazyk: angličtina
Zdroj: Methods and applications in fluorescence [Methods Appl Fluoresc] 2020 Feb 03; Vol. 8 (1), pp. 014008. Date of Electronic Publication: 2020 Feb 03.
DOI: 10.1088/2050-6120/ab6366
Abstrakt: We report the spectral properties of 2-Phenylindole (2PI) embedded in rigid poly (vinyl alcohol) (PVA) film. The 2PI in PVA film shows relatively strong and structured fluorescence with a maximum at 370 nm and surprisingly strong room temperature phosphorescence with an emission maximum of about 500 nm. The dye is highly immobilized in the polymer matrix, thus presenting high fluorescence anisotropy in an isotropic film of about 0.3 at room temperature. The 2-Phenylindole phosphorescence excited in the usual way through the electronic singlet state excitation (S 0  → S 1 absorption) results in a very low, near zero anisotropy. We now report that we can directly excite the dye to the triplet state T 1 and observe high phosphorescence anisotropy similar to the fluorescence anisotropy. The extinction coefficient for S 0  → T 1 absorption in the PVA matrix is unusually high- only about 3 orders of magnitude lower than S 0  → S 1 absorption. We consider this direct excitation to indole's triplet state a very significant finding that may lead to many practical applications. The unusually long-wavelength of excitation around 400 nm, much above typical UV absorption, results in a high phosphorescence anisotropy. This provides a new way to study rotational motion of larger biological objects in the microsecond time scale not accessible through typical fluorescence studies.
Databáze: MEDLINE
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