Fluorescent film sensor for copper ion based on an assembled monolayer of pyrene moieties

We previously reported the construction of a family of fluorescent film sensors for organic copper salts by covalently coupling polycyclic aromatic hydrocarbons on epoxy-terminated self-assembled monolayers on glass plate surfaces. Here we investigate the sensing properties and mechanism of covalently coupling pyrene on a glass plate surface via a long flexible “Y” type spacer. X-ray photoelectron spectroscopy (XPS) and fluorescence spectra measurements demonstrate the covalent attachment of pyrene in our adlayer. Compared with those results obtained in the previous studies, this new film sensor did not show highly selectivity for organic copper salts, which can be attributed to the introduction of sulfonyl groups connecting the pyrene moieties and the spacers. The presence of sulfonyl units made the microenvironments of pyrene relatively hydrophilic and thus showed less screening effect for inorganic ions. The specificity and reversibility of the film sensor toward Cu (II) made it attractive for sensing applications.

Fluorescence lifetime data revealed that the quenching mechanism of the copper (II) ions to the emission of this new “Y” type spacer film is a combination of static and dynamic quenching, which consistent with less screening effect of spacer layer due to the introduction of the sulfonyl groups connecting the spacers and pyrene moieties.Figure optionsDownload as PowerPoint slideHighlights
► Pyrene derivative was tethered on epoxy-terminated SAM via “Y” type spacer.
► The fabricated film senor was sensitive to copper (II) ions in aqueous solution.
► The microenvironments effect imparts this new film sensor different performance.
► The response of the film sensor to copper (II) ions is specific and reversible.