Steady-State and Femtosecond Transient Absorption Spectroscopy of New Two-Photon Absorbing Fluorene-Containing Quinolizinium Cation Membrane Probes

    Authors

    X. L. Yue; Z. Armijo; K. King; M. V. Bondar; A. R. Morales; A. Frazer; I. A. Mikhailov; O. V. Przhonska;K. D. Belfield

    Comments

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    Abbreviated Journal Title

    ACS Appl. Mater. Interfaces

    Keywords

    quinolizinium derivatives; fluorescence probes; two photon absorption; femtosecond transient absorption spectroscopy; fluorescence bioimaging; HUMAN SERUM-ALBUMIN; LIGHT-UP PROBES; ORGANIC-MOLECULES; ENERGY-TRANSFER; LIVING CELLS; PUMP-PROBE; DERIVATIVES; DNA; CHROMOPHORES; BINDING; Nanoscience & Nanotechnology; Materials Science, Multidisciplinary

    Abstract

    The synthesis, linear photophysical characterization, and nonlinear optical properties of two new symmetrical fluorene-containing quinolizinium derivatives, 2,8-bis((E)-2-(7-(diphenylamino)-9,9-dihexyl-9H-fluoren-2-yl)vinyl)quinolizinium hexafluorophosphate (1) and 2,8-bis((E)-2-(7-((7-(diphenylamino)-9,9-dihexyl-9H-fluoren-2-yl)ethynyl)-9,9-dihexyl-9H-fluoren-2yl)vinyl)quinolizinium hexafluorophosphate (2), are reported. The nature of the dual-band steady-state fluorescence emission of 1 and 2 was determined, and violation of Kashas rule along with a strong dependence on solvent polarity were shown. A relatively complex structure of two-photon absorption (2PA) spectra of 1 and 2, with maximum cross sections of similar to 400600 GM, was determined using the open aperture Z-scan method. Different types of fast relaxation processes with characteristic times of 0.30.5 ps and 1.52 ps were observed in the excited states of the new compounds via femtosecond transient absorption pumpprobe spectroscopy. To better understand the photophysical behavior of 1 and 2, a quantum-mechanical study was undertaken using TD-DFT and ZINDO/S methods. Simulated linear absorption spectra were found to be in good agreement with experimental data, while 2PA cross sections were overestimated. Although the new dyes were highly fluorescent in nonpolar solvents, they were essentially nonfluorescent in polar media. Significantly, the quinolizinium dyes exhibited fluorescence turn-on behavior upon binding to bovine serum album (BSA) protein, exhibiting over 4-fold fluorescence enhancement, which was a finding that was leveraged to demonstrate cell membrane fluorescence imaging of HeLa cells.

    Journal Title

    Acs Applied Materials & Interfaces

    Volume

    7

    Issue/Number

    4

    Publication Date

    1-1-2015

    Document Type

    Article

    Language

    English

    First Page

    2833

    Last Page

    2846

    WOS Identifier

    WOS:000349137300083

    ISSN

    1944-8244

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