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Spectroscopic investigations, characterization and chemical sensor application of composite Langmuir–Schäfer films of anthocyanins and oligophenylenevinylene derivatives

Year: 2012

Journal: Dyes and Pigments 94 (2012) 156e162, 20121205

Authors: S. Bettini, L. Valli, A. Santino, C. Martinelli, G. M. Farinola, A. Gardone, V. Sgobba, G. Giancane

Organizations: Dipartimento di Ingegneria dell’Innovazione, Università del Salento, Via Monteroni, 73100 Lecce, Italy; Institute of Sciences of Food Production C.N.R. Unit of Lecce, Via Monteroni, 73100 Lecce, Italy; Dipartimento di Chimica, Università di Bari, via Orabona 4, Bari I-70125, Italy; Istituto Chimica dei Composti OrganoMetallici, CNR-ICCOM, Dipartimento di Chimica, Università di Bari, via Orabona 4, Bari I-70125, Italy; Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials University Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany

Anthocyanins, extracted from grape skin (Vitis vinifera), were dissolved in ultrapure aqueous subphase and an oligophenylenevinylene derivative was spread on the subphase surface. Such oligomer was chosen as anionic counterpart of hydrosoluble anthocyanins in order to perform a Langmuir–Schäfer film of the dyad. Interface interactions between oligophenylenevinylene derivative and anthocyanins were studied by Brewster angle microscopy and reflection spectroscopy. Additionally, the oligomer exhibits a chemical structure able to ensure an enhancement of the stability under UV–visible irradiations of the film of the dyad without any variation of the natural pigment absorption in the visible range. The visible spectra of cast anthocyanins film and Langmuir–Schäfer oligomer/anthocyanins film after exposure to 254 nm irradiation showed a remarkable increase of the film stability, probably due to the screening effect of the oligomer. Preliminary test of a Langmuir–Schäfer film of oligophenylenevinylene derivative/anthocyanins as a herbicide sensor showed that sensing is completely reversible, stable and repeatable.