Incorporação de porfirinas em matrizes Sol-Gel: Preparação e caracterização espectroscópica

Abstract

In recent years, porphyrins and their derivatives have been highlighted in scientific studies due to their catalytic and luminescent properties. A wide variety of photosensitizing agents were produced and they have been extensively studied because of their photophysical and photochemical properties. Immobilization of porphyrins in sol-gel matrices is of great interest because their applications in chemical and biochemical sensors, increasing their photostability, and catalysts. The acquisition of inorganic matrices through the sol-gel process is a promising way to reach supporters of high purity and homogeneity, and much lower processing temperature compared those formed by traditional methods of obtaining coatings. Thus, we studied in this work the incorporation of porphyrins, Tetrakis (N-methyl-4-pyridyl) porphyrin (TMPyP) in the free base and complexed with Fe 3 +, Fe (III) Tetrakis (N-methyl-4-pyridyl) porphyrin (FeTMPyP) in sol-gel matrices. Was synthesized and compared two methods of preparing the gels, Pechini method, the polymeric precursors method, and sol-gel method using TEOS (tetraethylorthosilicate), a method that consists in the hydrolysis of tetraethylorthosilicate, in the form of thin films. The deposition of the gels was done on glass slides for microscopy through techniques Dip and Spin - Coanting and then compared. The films were characterized by the steps of: Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Atomic Force Microscopy (AFM). The film obtained by the Pechini method was more qualified for the incorporation of porphyrins, as it showed more homogeneous structures. The porphyrins were incorporated into films by Dip and Spin-Coating techniques. The films were characterized again to confirm the presence of porphyrins in films through the techniques Fourier Transform Infrared Spectroscopy (FTIR) and Ultraviolet-Visible Spectroscopy (UV/Vis). The results showed that the porphyrins were incorporated into the films made by the Pechini technique by Dip- Coating.