Sensing Ability of Zn-Tetraphenylporphyrin Langmuir-Schaefer Films

Abstract

The floating layers formation conditions of Zn(II)-5,10,15,20tetraphenylporphyrin (ZnTPP) at the air/water interface and Langmuir-Schaefer films (LS-films) obtained on glass and silicon substrates have been studied. The floating layers were modeled and the geometric characteristics of molecular packings on water surface were calculated. It was shown that the area per molecule in the dense face-on packing of a monolayer is 1.69 nm 2 , and in the edge-on packing -0.90 nm 2 . Analysis of the floating layer compression isotherm revealed that ZnTPP molecules are arranged face-on to the interface plane. Electron absorption spectroscopy showed that LS-films contain aggregates of J-type. The surface morphology of LS-films studied by AFM revealed that the average roughness of LS-films increases by 1.4 times with an increase in the number of transfers from one to five. The sensing properties of the LS-films (with 15 transfers) with respect to hydroxypyridine and pyridine in aqueous and gaseous media, correspondingly, have been studied. It was established that the LS-film is sensitive to pyridine vapors. The results obtained can be used to create selective sensors for environmental pollution monitoring.