Calix[4]arene-functionalized poly-yclopenta[2,1-b;3,4-b']bithiophenes with good recognition ability and selectivity for small organic molecules for application in QCM-based sensors

Some C2v symmetric cyclopenta[2,1-b;3,4-b’]bithiophenes differently substituted at the 4 position with acalix[4]arene group were synthesized and electrochemically polymerized by anodic coupling. The polymerswere characterized by cyclic voltammetry, UV-vis and FTIR spectroscopy. Quartz crystal microbalanceanalysis showed strong affinity and selectivity of the polymers for toluene and acetone from the gas phase. Theabsorption process associated with the calix unit was satisfactorily described through a Langmuir isotherm,while a very small linear contribution was given by the polythiophene backbone. The absorption capacityof these materials was found to be higher by a magnitude of three orders than those displayed bycyclopentabithiophene-based polymers devoid of the calix unit, thus supplying strong, though indirect, proof ofthe role played by the calix units in the absorption process.