New selective gas sensor based on piezoelectric quartz crystal modified by electropolymerization of a molecular receptor functionalised with 2,2′-bithiophene

A new gas sensor suiting the quartz crystal microbalance (QCM) technology has been realized and studied. The sensor is obtained by electropolymerization, onto the surface of a gold-coated piezoelectric quartz crystal (PQC), of a molecular receptor properly functionalised with 2,2′-bithiophene. The obtained polymeric coating has shown to be able to selectively form hydrogen bonds with organic molecules containing electronegative atoms like chloroform, acetone, ethyl acetate, ethanol even in presence of hexane or toluene which do not interact with the receptor. The easy electrosynthetic preparation and the specificity of the response are the fundamental advantages of such a polymeric films. The effectiveness of the immobilized receptor has been tested in comparison with the responses obtained with PQCs coated with unfunctionalised poly(2,2′-bithiophene). The sensor also showed good reproducibility and fairly long lifetime.