Sensing of linear alkylammonium ions by a 5-pyrenoylamido-calix[5]arene solution and monolayer using luminescence measurements

Covalent chemisorption of a p-chloromethylphenyltrichlorosilane monolayer on silica substrates was achieved. A cone 5-pyrenoylamido-calix[5]arene bearing a 12-aminododecyl moiety at the lower rim was further covalently bonded, producing a 5-pyrenoylamido-calix[5]arene-based monolayer on silica. The surface chemical characterization of this hybrid material was carried out by X-ray photoelectron spectroscopy. The sensing properties of this pyrenoylamido-calix[5]arene system were probed by both NMR and luminescence measurements in solution. The optical recognition properties of the functional monolayer were similarly studied at room temperature by emission measurements. This system demonstrates to have significant recognition properties for the linear alkylammonium ions. As a result, n-dodecylammonium ions can be detected at ppm levels. The adopted synthetic procedure provided evidence to be useful in transferring molecular properties to a solid state device.