Highly Selective Chemical Vapor Sensing by Molecular Recognition: Specific Detection of C_1-C_4 Alcohols with a Fluorescent Phosphonate Cavitand

摘要

In the last few years there has been a huge demand to monitor different chemical species in the vapor phase, such as environmental pollutants, hazardous chemicals, food aromas, explosives, and volatiles in breath for disease diagnosis. Chemical vapor sensors are among the most promising devices to be exploited for these applications, because they have the great advantage of allowing an online measure suitable for remote control. In this context, the need to develop sensors specific for different classes of analytes is well-recognized and confirmed by the considerable research efforts spent for the preparation of more and more efficient devices. The crucial parameter to define the success of a given sensor is therefore selectivity, and for this reason the strategy to prepare the sensing material following the principle of supramolecular chemistry has quickly gained increasing importance. However, the realization of selective chemical vapor sensors requires particular attention since they operate at the gas-solid interface. Any given analyte, upon moving from the vapor to the solid phase, experiences a dramatic increase in non-specific dispersion interactions, which tend to override any specific complexation event responsible for the selective responses. As a result, the sensor selectivity drops and false positive responses soar. A possible solution to this general problem relies on transduction modes activated exclusively by the molecular recognition event.