Excited State Intramolecular Proton Transfer and Photophysics of a New Fluorenyl Two‐Photon Fluorescent Probe |
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| Authors: | Alma R. Morales Dr. Katherine J. Schafer‐Hales Dr. Ciceron O. Yanez Mykhailo V. Bondar Dr. Olga V. Przhonska Dr. Adam I. Marcus Prof. Kevin D. Belfield Prof. |
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| Affiliation: | 1. Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, FL 32816‐2366 (USA), Fax: (+1)?407‐823‐2252;2. Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA 30322 (USA);3. Institute of Physics, Prospect Nauki, 46, Kiev‐28, 03028 (Ukraine);4. CREOL, The College of Optics and Photonics, University of Central Florida, P.O. Box 162366, Orlando, FL 32816‐2366 (USA) |
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| Abstract: | The steady‐state photophysical, NMR, and two‐photon absorption (2PA) properties of a new fluorene derivative ( 1 ) containing the 2‐(2′‐hydroxyphenyl)benzothiazole (HBT) terminal construct is investigated for use as a fluorescence probe in bioimaging. A comprehensive analysis of the linear spectral properties reveals inter‐ and intramolecular hydrogen bonding and excited state intramolecular proton transfer (ESIPT) processes in the HBT substituent. A specific electronic model with a double minimum potential energy surface is consistent with the observed spectral properties. The 2PA spectra are obtained using a standard two‐photon induced fluorescence method with a femtosecond kHz laser system, affording a maximum 2PA cross section of ～600 GM, a sufficiently high value for two‐photon fluorescence imaging. No dependence of two‐photon absorption efficiency on solvent properties and hydrogen bonding in the HBT substituent is observed. The potential use of this fluorenyl probe in bioimaging is demonstrated via one‐ and two‐photon fluorescence imaging of COS‐7 cells. |
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| Keywords: | bioimaging agents fluorescent probes hydrogen bonding photophysics two‐photon induced fluorescence |
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