Síntese e caracterização de um novo derivado calix[4]areno funcionalizado com o grupamento oxamato: potenciais aplicações como agente complexante

Abstract

The calix[4]arene is the smallest compound of the calixarene class, structurally composed of four phenolic units linked at the ortho position by methylene bridges. In summary, calixarenes are excellent construction platforms, as they have simple, stable structures, are easily functionalized, and are derived from low-cost precursors. Given the emerging demand for new technological materials aimed at industrial and medicinal applications, this work proposes the synthesis and study of the properties of calix[4]arene functionalized with the oxamate group. Oxamate-based compounds have gained prominence in the field of Coordination Chemistry, particularly in the exploration of complexes with magnetic and luminescent properties. Oxamate is a versatile complexing agent that, through its structure composed of amide and carboxylic acid functional groups, enables the coordination of various metals in a bidentate manner and the formation of polynuclear complexes. In this context, we developed a new calix[4]arene containing four oxamic acid units on the upper rim of its structure, achieved through a six-step synthesis route starting from p-tert-butylphenol. Additionally, 2-((4-butoxyphenyl)amino)-2-oxoacetic acid was synthesized via a four-step synthesis route starting from p-nitrophenol. This compound was developed as a reference to assess, in the future, the influence of the cyclic tetramer on metal coordination compared to its respective monomer. Based on the results obtained in the synthetic stage and characterization by infrared spectroscopy, nuclear magnetic resonance, and high-resolution mass spectrometry, p-oxamic-butoxycalix[4]arene was successfully obtained with an overall yield of 12%.