A Silsesquioxane Organically Modified with 4-Amino-5-(4-pyridyl)-4H-1,2,4-triazole-3-thiol: Thermal Behavior and Its Electrochemical Detection of Sulfhydryl Compounds

D R Do Carmo,N L Dias Filho,D R Silvestrini,U O Bicalho,H S Barud,L A Soares

doi:10.1155/2014/695954

Abstract

The octakis(3-chloropropyl)silsesquioxane (SS) was organofunctionalized with 4-amino-5-4(pyridyl)-4H-1,2,4-triazole-3-thiol. The product formed (SA) was undergo another reactions in two steps, first with copper and so hexacyanoferrate (III) to form CuHSA. The organofunctionalized silsesquioxane was characterized by the following techniques: scanning electron microscopy (SEM), Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) in solid state, and thermogravimetric analysis in air and nitrogen atmosphere. The composite CuHSA was incorporated into a graphite paste electrode and the electrochemical behavior studies were conducted with cyclic voltammetry. The cyclic voltammogram of the modified graphite paste electrode with CuHSA showed one redox couple with formal potentialEθ′=0.75 V versus Ag/AgCl(sat)(KCl 1.0 mol L−1;v= 20 mV s−1) attributed to the redox process Fe(II)(CN)6/Fe(III)(CN)6of the binuclear complex formed. The redox couple presents an electrocatalytic response of sulfhydryl compounds such as n-acetylcysteine and l-cysteine. For determination of n-acetylcysteine and l-cysteine the modified graphite paste electrode showed a linear region in the concentration range of 2 to 20 mmol L−1. The modified electrode was chemically and electrochemically stable and showed good reproducibility.

Highlights

In recent years, the development of hybrid materials has been the subject of considerable attention of the scientific community due to their organic and inorganic moieties working together to give the hybrid different properties from those displayed in their precursors [1]
In this paper we present the preparation, characterization, and voltammetric study of copper hexacyanoferrate (CuHCF) obtained by the interaction with the functionalized cubic polyhedral oligosilsesquioxane (SS) and 4-amino-5(4-pyridyl)-4H-1,2,4-triazole-3-thiol (APTT) (SA) in two stages
The thermogravimetric analysis studies showed that this new material (SA) showed relative thermal stability up to temperatures of around 250∘C, a common behavior in analogous compounds reported in the literature [50]

Summary

Introduction

The development of hybrid materials has been the subject of considerable attention of the scientific community due to their organic and inorganic moieties working together to give the hybrid different properties from those displayed in their precursors [1]. There is great interest in the formation of hybrid materials by incorporating organic groups into structures of silsesquioxanes [2]. Hybrid organic/inorganic composites from silsesquioxanes, nanostructured compounds with an empirical formula (RSiO1.5)n, where R is a hydrogen atom or an organic group [3] and n = 4, 6, 8, 10 (n ≥ 4) [4], have wide applications, for instance, as catalysts [5, 6], liquid crystals [7, 8], nanofillers [9], sensors and biosensors [10, 11], silica interface [12, 13], medicine [14, 15], and dendrimer precursors [14, 16].

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