Fabrication and characterization of calix[4]arene Langmuir–Blodgett thin film for gas sensing applications

In this work, the Langmuir–Blodgett (LB) technique was applied onto the different substrates such as quartz, quartz crystals and gold coated glass for fabricating LB thin films with 25,27-(Dipropylmorpholinoacetamido)-26,28-dihydroxycalix[4]arene. The characteristics of the calix[4]arene LB films were evaluated by UV–Vis, atomic force microscopy (AFM), quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) measurements. The mass deposited on the quartz crystal per bilayer was predicted as 2028.80 ng (7.65 ng mm−2) for the calix[4]arene LB film. The sensing abilities of this LB film towards the development of room temperature organic vapor sensing devices were also examined. QCM and SPR systems were fixed to investigate vapor sensing performance of macrocyclic LB films during exposure to volatile organic compounds (VOCs). The macrocyclic LB thin films were more sensitive to dichloromethane than other vapors. The sensitivity and detection limit values of the calix[4]arene QCM sensor to dichloromethane vapor were calculated as 2.023 Hz ppm−1 and 1.482 ppm, respectively. The sensitivities of the calix[4]arene LB films against organic vapors can be explained with the host–guest interaction between the cavity of molecule and the organic vapor molecules. It is determined that the calix[4]arene LB film is more sensitive to dichloromethane than other vapors at room temperature and the calix[4]arene is a promising material serving as a vapor sensing device.