title: Excited state intramolecular proton transfer and photophysics of a new fluorenyl two-photon fluorescent probe.
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 approximately 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.
authors.affiliation: Department of Chemistry, University of Central Florida, P.O. Box 162366, Orlando, FL 32816-2366, USA.
authors.forename: Alma R
authors.initials: AR
authors.lastname: Morales
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Schafer-Hales
authors.forename: Ciceron O
authors.initials: CO
authors.lastname: Yanez
authors.forename: Mykhailo V
authors.initials: MV
authors.lastname: Bondar
authors.forename: Olga V
authors.initials: OV
authors.lastname: Przhonska
authors.forename: Adam I
authors.initials: AI
authors.lastname: Marcus
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Belfield
mesh_terms: D000042:Absorption; D000818:Animals; D052160:Benzothiazoles / Q000138:chemical synthesis / Q000737:chemistry*; D001692:Biological Transport; D019556:COS Cells; D002522:Chlorocebus aethiops; D005456:Fluorescent Dyes / Q000737:chemistry*; D011522:Protons; D013050:Spectrometry, Fluorescence
chemical_list: D052160:Benzothiazoles; D005456:Fluorescent Dyes; D011522:Protons; C005465:benzothiazole