Linear Photophysics And Femtosecond Nonlinear Spectroscopy Of A Star-Shaped Squaraine Derivative With Efficient Two-Photon Absorption

Abstract

The synthesis, comprehensive linear photophysical and photochemical study, two-photon absorption (2PA) spectrum, ultrafast relaxation kinetics in the excited states, and efficient superluminescence properties of a new symmetrical three-armed star-shaped squaraine derivative (1) are presented. The steady-state spectral parameters of 1 in a number of organic solvents, including fluorescence excitation anisotropy spectra, revealed a weak interaction between the squaraine branches and the effect of symmetry breaking in the ground electronic state. The degenerate 2PA spectrum of 1 was obtained over a broad spectral range with a maximum cross section of ∼8000 GM using the open aperture Z-scan technique. The nature of the fast dynamic processes in the excited electronic states of 1 was investigated by the femtosecond transient absorption pump-probe method, revealing characteristic relaxation times of ∼3-4 ps. The efficient superluminescence emission of 1 was observed in relatively low concentration solution (2.3·10-4 M) under femtosecond transverse pumping. A quantum-chemical study of 1 was performed using ZINDO/S//DFTB theory levels. Simulated 1PA and 2PA absorption spectra were found to be in a good agreement with experimental data. The figure of merit for 1 is ∼1011 GM,1 one of the highest values ever reported for two-photon fluorescence molecular probes, suggesting strong potential for its application in two-photon fluorescence microscopy and bioimaging.

Publication Date

5-26-2016

Publication Title

Journal of Physical Chemistry C

Volume

120

Issue

20

Number of Pages

11099-11110

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1021/acs.jpcc.6b02446

Socpus ID

84973110330 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84973110330

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