Banca de DEFESA: JOSE DANIEL DA SILVA FONSECA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JOSE DANIEL DA SILVA FONSECA
DATE: 21/03/2022
TIME: 08:30
LOCAL: Auditório Virtual Benício de Barros Neto
TITLE:

SYNTHESIS AND CHARACTERIZATION OF THE PLATFORM BASED ON NH2-UiO-66 METALORGANIC FRAMEWORK AND CALIX[4]ARENE DERIVATIVE FOR FLOURESCENT DETECTION OF Fe3+

KEY WORDS:

fluorescent sensor, Fe³⁺ detection, calixarenes, metal-organic frameworks.

PAGES: 88
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

Calixarenes are cyclic macromolecules formed by the condensation of phenolic units in an alkaline medium. The molecule's cavity enables the formation of host-guest complexes and the potential application as fluorescent sensors. Metal-organic frameworks are a class of materials with high surface area, adjustable pore size, and structural diversity. Such characteristics make these materials interesting for the application in sensing, catalysis, drug delivery, gas storage, among others. Through proper functionalization, other materials can be incorporated into the metal-organic framework, conferring additional properties. The objective of this work is the synthesis of a platform based on p-tert-butylcalix[4]arene-tetra-acid (CALIX) and MOF UiO-66-NH₂ and its potential application as a fluorescent sensor. The p-tert-butylcalix[4]arene-tetra-acid was synthesized by esterification followed by basic hydrolysis of p-tert-butylcalix[4]arene in 90% yield. The MOF UiO-66-NH₂ was synthesized via solvothermal method from the ligand 2-aminoterephthalic acid and zirconium chloride. The CALIX@UiO-66-NH₂ platform was synthesized by linking the amino groups of the MOF with the CALIX carboxylic groups. The materials were characterized by NMR ¹H, FTIR, XRD, TGA, and fluorescence. The NMR ¹H analysis showed the characteristic signals for CALIX, suggesting the successful synthesis and the desirable cone conformation. The X-ray diffraction pattern of the MOF showed similarity to the pattern calculated for (C₄₈ H₂₈ O₃₂ Zr₆)_n. The diffraction pattern indicated that the platform has a different structure from its precursors. CALIX@UiO-66-NH₂ showed irregular morphology with MOF particles on the calixarene surface. The CALIX@UiO-66-NH₂ platform showed higher fluorescence than the precursor components, making its use as a fluorescent sensor promising. The platform was used for the detection of several cations (Na⁺, Ca²⁺, Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺, Zn²⁺), with Fe³⁺ being the most suppressed fluorescence of the platform. The FTIR spectrum of the platform in the presence of Fe³⁺ suggested structural stability. Based on the calibration curve, the detection limit was found to be 6.74x10^-6 mol. L^-1 and the constant for the Stern-Volmer equation was K_SV=23 mol. L^-1. The presence of other cations in the detection of Fe³⁺ did not significantly interfere the platform response.

BANKING MEMBERS:
Interno - 1754300 - BRAULIO SILVA BARROS
Presidente - 2163324 - JOANNA ELZBIETA KULESZA
Externo à Instituição - LEONIS LOURENÇO DA LUZ - UFPE