Title

Synthesis of two-photon absorbing unsymmetrical fluorenyl-based chromophores

Authors

Authors

A. R. Morales; K. D. Belfield; J. M. Hales; E. W. Van Stryland;D. J. Hagan

Comments

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Abbreviated Journal Title

Chem. Mat.

Keywords

QUANTUM YIELD; ABSORPTION; DERIVATIVES; SPECTROSCOPY; ENHANCEMENT; MOLECULES; POLYMERS; DESIGN; DYES; Chemistry, Physical; Materials Science, Multidisciplinary

Abstract

Unsymmetrical fluorenyl-based chromophores, flanked on either side by electron-acceptor (A) and/or electron-donating (D) groups, separated by conjugated (pi) moieties, were synthesized. Heck coupling and Wittig reactions were utilized to prepare target fluorene derivatives that possess very high solubility in organic solvents, high thermal stability ( up to 395 degrees C), and generally high fluorescence quantum yields (0.6-0.9). The systematic alteration of the structural design allowed for investigation of numerous factors that affect the optical nonlinearity, as well as probing effects of molecular symmetry, solvent polarity, strengths of electron donating and/or withdrawing end groups, and pi-conjugation length. A detailed spectroscopic study of these molecules, including absorption, fluorescence emission, excitation, and excitation anisotropy, was conducted. Two-photon absorption (2PA) cross sections (delta) were determined by a nonlinear transmission method employing a femtosecond white-light continuum (WLC) pump-probe method, with all compounds exhibiting high two-photon absorption under femtosecond excitation. Compound 3 had a peak 2PA cross section, delta, of 1093 x 10(-50) cm(4) s photon(-1) molecule(-1) at 828 nm. In addition, excitation anisotropy studies permitted the determination of the spectral position of the S-0 -> S-1 and S-0 -> S-2 electronic transitions.

Journal Title

Chemistry of Materials

Volume

18

Issue/Number

20

Publication Date

1-1-2006

Document Type

Article

Language

English

First Page

4972

Last Page

4980

WOS Identifier

WOS:000240754100038

ISSN

0897-4756

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