Redes metalorgânicas com nanopartículas de Au como substratos SERS para detecção do pesticida tebuconazol em água

Abstract

Pesticides are chemical or biological substances used to prevent, control, or eliminate agricultural pests. One of the major problems with pesticides is their enormous capacity to contaminate environmental matrices, including aquatic ones. An example of a pesticide harmful to aquatic environments is tebuconazole, a triazole pesticide used to eliminate fungi. Monitoring pesticides in water is of great importance due to the potential environmental impacts and risks to human health. In this context, surface-enhanced Raman spectroscopy (SERS) has emerged as a promising analytical technique, as it allows for the reduction of the concentration of monitored substances by enhancing the Raman intensity of molecules adsorbed on nanostructured plasmonic surfaces. In parallel, metal-organic frameworks (MOFs) exhibit properties such as high surface area, high porosity, and structural versatility, making them attractive materials for modification with metallic nanoparticles and the formation of promising hybrid materials for use as SERS substrates in the detection of pesticides in water. This thesis presents the modification of the MOFs UiO-66, MIL-53- BDC, MIL-53-TDC, and HKUST-1 with gold nanoparticles using different strategies. The materials were characterized using various techniques, such as Raman, infrared, and UVVis-NIR spectroscopies, polycrystalline X-ray diffraction, dynamic light scattering, scanning electron microscopy, and thermal analysis. The hybrid materials based on HKUST1 showed structural instability in the presence of water, and it was found that modification using AuNPs dispersed in N,N-dimethylformamide preserves the MOF structure. Hybrid materials formed from UiO-66, MIL-53-BDC, and MIL-53-TDC MOFs modified with AuNPs demonstrated sufficient stability for use in detecting the pesticide tebuconazole in water using the SERS technique, with concentrations as low as 4.52 × 10⁻⁷ mol L⁻¹. This also enabled the study of drinking water. These results demonstrate the high potential of these materials for the study of tebuconazole in different matrices.