Piezoelectric crystal membrane chemical sensors based on fullerene C60

Various reusable and sensitive piezoelectric (PZ) quartz crystal membrane s ensors with home-made computer interfaces for signal acquisition and data p rocessing were developed to detect organic/inorganic vapors and organic/ino rganic species in solutions, respectively. Fullerene C60 and synthesized fu llerene derivatives, e.g. C60-cryptand22 and C60-dibenzo-16-crown-5 were ap plied as coating materials on quartz crystals of the PZ crystal sensors. Th e oscillating frequency of the quartz crystal decreased due to the adsorpti on of organic or inorganic species onto coating material molecules on the c rystal surface. The C60-coated PZ crystal sensor was firstly prepared to st udy the adsorption and the interaction between fullerene C60 and organic mo lecules. Only amines, dithios, alkynes and 1,3-dienes seem to perform chemi sorption onto fullerene while physical adsorption is found in all other cas es like alcohols, aldehydes and carboxylic acids. The reactivities of fulle rene C60 and other conjugated olefins to various organic molecules seem to be in the order p-carotene > C60 > pyrene. The fullerene C60-coated PZ crys tal sensor also can be employed to sensitively detect some organic molecule s, e.g. aldehydes, carboxylic acids, amines and olefins. A C60-cryptand22-c oated PZ gas sensor for both polar/nonpolar organic vapors was also prepare d. The cryptand22-coated PZ gas sensor can be employed as a GC detector for organic molecules. The C60-cryptand22-coated crystal GC-PZ detector compar ed well with the commercial thermal conductivity detector (TCD). Various li quid PZ crystal sensor based on C60-cryptand22 and dibenzo-16-crown-5-C60 w ere also prepared as liquid chromatographic (LC) detectors for metal ions, anions and polar/ nonpolar organic molecules in solutions. The frequency re sponses of the C60-cryptand22-coated LC-PZ detectors for various organic mo lecules and metal ions were compared well with the responses of a commercia l UV-VIS detector and a conductivity detector which are generally used in L C systems. (C) 2001 Elsevier Science B.V. All rights reserved.