Spectroscopic investigations, characterization and chemical sensor application of composite LangmuireSchäfer films

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 LangmuireSchäfer
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 UVevisible 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 LangmuireSchäfer 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 LangmuireSchäfer film of oligophenylenevinylene
derivative/anthocyanins as a herbicide sensor showed that sensing is completely reversible, stable and
repeatable.