Controlled Aggregation and Enhanced Two-Photon Absorption of a Water-Soluble Squaraine Dye with a Poly(acrylic acid) Template

    Authors

    Y. W. Zhang; B. Kim; S. Yao; M. V. Bondar;K. D. Belfield

    Comments

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    Abbreviated Journal Title

    Langmuir

    Keywords

    LANGMUIR-BLODGETT-FILMS; ANIONIC POLYELECTROLYTES; SURFACTANT; SQUARAINES; MOLECULAR-STRUCTURE; SQUARIC ACID; CA2+ IONS; DYNAMICS; FLUORESCENCE; BEHAVIOR; BINDING; Chemistry, Multidisciplinary; Chemistry, Physical; Materials Science, ; Multidisciplinary

    Abstract

    Controlling the aggregation behavior of organic dyes is important for understanding and exploring supramolecular assembly utilizing the specific characteristics of aggregation. Regulating J-aggregation by electrostatic interactions between anionic polyelectrolytes and cationic dyes has gained growing interest. Here, we report the formation of J-aggregates of a water-soluble cationic squaraine dye, 4(pyridinium-1-yl)butylbenzothiazolium squaraine (SQ), using poly(acrylic acid) sodium salt (PAA-Na) as a template. Electrostatic interactions between the PAA-Na polyelectrolyte and the cationic SQ dye enhanced J-aggregation; the absorbance. of the resulting J-band with the polyelectrolyte template was much sharper than the absorbance of the J-aggregate formed using a high concentration of NaCl. Significantly, removal of the polyelectrolyte PPA-Na template by the introduction of calcium ions, which can form stronger ionic binding with carboxylate groups, dissociated J-aggregates, freeing the SQ molecules back to unaggregated or lower aggregate forms. To demonstrate the reversibility of the J-aggregate formation cycle, an in situ experiment was conducted that showed 60% reversibility of the second cycle. In addition, an enhancement by ca. 23 times per repeat unit of the two-photon absorption (2PA) cross section was observed at 920 nm for the polyelectrolyte template-SQ J-aggregate compared to unaggregated or lower aggregate SQ These results suggest a prominent role of polyelectrolyte templated SQ J, aggregation in the enhancement of 2PA efficiency and provide a means of modulating supramolecular assembly.

    Journal Title

    Langmuir

    Volume

    29

    Issue/Number

    35

    Publication Date

    1-1-2013

    Document Type

    Article

    Language

    English

    First Page

    11005

    Last Page

    11012

    WOS Identifier

    WOS:000326128900005

    ISSN

    0743-7463

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