Pb2+ and Cd2+ selective chemically modified field effect transistors based on thioamide functionalized 1,3-alternate calix[4]arenes

Novel calix[4]arenes fixed in the 1,3-alternate conformation and functionalized with thioamide groups have been synthesized and their selectivities for Pb2+ and Cd2+ ions in chemically modified field effect transistors (CHEMFETs) have been evaluated. The 25,27-bis(dimethylaminothiocarbonylmethoxy)-26,28-dipropoxycalix[4]arene 3 in the 1,3-alternate conformation is more selective for Pb2+ than the analogous cone conformer. The 1,3-alternate calix[4]arene 8 having, in the 25- and 27-positions, two pairs of vicinal thioamide moieties at the same face of the molecule, has the highest selectivities for Cd2+ reported so far.