Aggregation-enhanced two-photon absorption and up-converted fluorescence of quadrupolar 1,4-bis(cyanostyryl)benzene derivatives showing solvatochromic fluorescence

Su Bum Noh, Ran Hee Kim, Won Jin Kim, Sehoon Kim, Kwang Sup Lee, Nam Sung Cho, Hong Ku Shim, Haridas E. Pudavar, Paras N. Prasad

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Abstract

This paper reports synthesis and semiempirical modeling of 1,4-bis(cyanostyryl)benzene (CSB)-based quadrupolar isomeric molecules (α- and β-CSB-TPs), designed to produce enhancement in fluorescence quantum yield and two-photon absorption cross-sections for the nanoaggregate form. Fluorescence yield together with high two-photon optical properties of the isomers have been fine-tuned by moving the cyano group from α to β position, which results in longer absorption-fluorescence wavelengths, and higher one- and two-photon absorptivities for the β-CSB-TP. In nonpolar toluene solution, both isomers exhibit strong one- and two-photon induced fluorescence. Both isomers followed a trend of strong solvatochromisms which was gradually on increasing solvent polarity. Aqueous dispersions of nanoparticles with diameters of ca. 150 nm have been prepared by aggregation of each isomer. The quenched fluorescence in polar media was greatly intensified followed by a 21 fold increase in TPA cross-sections. This helped achieve intense up-converted fluorescence by two-photon absorption of excited β-CSB-TP organic nanoparticles. Coaggregation-enhanced tunable fluorescence has also been demonstrated as a possible application of the isomeric α- and β-CSB-TP mixture.

Original languageEnglish
Pages (from-to)7422-7429
Number of pages8
JournalJournal of Materials Chemistry
Volume20
Issue number35
DOIs
Publication statusPublished - 2010 Sep 21
Externally publishedYes

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ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Chemistry

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