Spectroelectrochemical Investigation of Double-Walled Tubular J-Aggregates of Amphiphilic Cyanine Dyes

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• 作者：Jennifer L. Lyon ; Dö ; rthe M. Eisele ; Stefan Kirstein ; J&uuml ; rgen P. Rabe ; David A. Vanden Bout ; Keith J. Stevenson
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：January 31, 2008
• 年：2008
• 卷：112
• 期：4
• 页码：1260 - 1268
• 全文大小：433K
• 年卷期：v.112,no.4(January 31, 2008)
• ISSN：1932-7455

文摘

The amphiphilic cyanine dye 3,3'-bis(2-sulfopropyl)-5,5',6,6'-tetrachloro-1,1'-dioctylbenzimidacarbocyanine(C8S3) self-assembles in aqueous solution to form double-walled, tubular J-aggregates with ~13 nm diametersand lengths up to several hundred nanometers. The redox and light absorption properties of immobilizedJ-aggregates on transparent, conductive indium tin oxide (ITO) electrodes have been studied directly usingcyclic voltammetry (CV) in conjunction with UV-vis spectroscopy to elucidate unique mechanistic featuresof J-aggregate oxidation. Morphological properties were examined using in situ atomic force microscopy(AFM). Irreversible J-aggregate oxidation appears to occur primarily along the outer wall of the tubular structureas evidenced by the potential-induced irreversible bleaching of J-band absorption. Voltammetric studies as afunction of scan rate and pH indicate that J-aggregate oxidation involves both electrochemical and chemicalsteps in which dimerization and subsequent dehydrogenation of the J-aggregate leads to the formation of anew dehydrogenated dimer oxidation product. This dehydrogenated dimer exhibits an absorbance band near560 nm along with a reversible reduction peak characteristic of a surface-confined, redox-active species.Excellent correlation of J-aggregate redox potentials with spectroelectrochemical data is obtained that allowsus to understand energetic thresholds for electron transfer in C8S3 tubular J-aggregates.