Abstract

We report in this paper the Cd2+ ion sensing by a fluorene appended piperidin-4-one which is encapsulated by beta-cyclodextrin-tethered gold nanoparticles. The thiolated cyclodexrin is synthesized and it forms a monolayer on gold nanoparticles through self-assembly. The structure of the thiolated cyclodextrin and the synthesized piperidin-4-one are characterized using spectroscopic techniques. 2-dimensional rotating frame Overhauser spectroscopy is employed to optimize the structure of the host-guest complex. The piperidin-4-one is encapsulated by the cyclodextrin molecule also when assembled on the gold nanoparticles. In the assembled monolayer form, the host-guest complex selectively binds Cd2+ ion in aqueous medium. The binding constant of 1: 2 complex is 5.61 (+/- 0.24) x 10(6)M(-2). The Cd2+ ion sensing is facile also in the cyclodextrin complex selfassembled on gold nanoparticles. The selectivity and sensitivity of the complex are explained. Gold nanoparticle-cyclodextrin assembly act as a scaffold for the chemosensor molecule.