Thiacalixarene self-assembled monolayers on roughened gold surfaces and their potential as SERS-based chemical sensors

We report the development of a chemical sensor dependent on self-assembled monolayers of a thiacalixarene on rough quartz-silica-gold surfaces. The calixarene assemblies were shown to display surface-enhanced Raman spectroscopic (SERS) signals from 'adsorbed' (host-guest intercalates) analyte molecules from dilute aqueous solutions (down to 10(-3) M). The response was used to demonstrate the sensing potential of both uncovered and functionalized surfaces for benzene, toluene, alkylbenzenes and benzonitrile. Sensitivity was limited by saturation effects in the millimolar region and the signal-to-noise ratios achievable at lower concentrations. Selectivity was demonstrated for benzene vs toluene and benzene vs benzonitrile mixtures. Although detailed elucidation of the analyte surface interactions was not attempted, both reversibility and selectivity appear to be better on the functionalized (rather than on the bare) surfaces, Copyright (C) 2001 John Wiley & Sons, Ltd.