Supramolecular p-sulfonated calix[4,6,8]arene for tryptophan detection

Numerous techniques have focused on the ability of p-sulfonated calix[n]arene to form complexes with tryptophan. Scanning electron microscopy and Fourier transform infrared spectroscopy were utilized to study the organization and molecular structure of different layers of the electrode surface. Scanning electron microscopy results showed that SC4A displayed a cubic structure whereas SC6A and SC8A displayed dendrite structures. The electrochemical properties and potential complex formation between SCnA and tryptophan were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry experiments showed that the gold electrode was successfully functionalized by self-assembled cysteamine and SC4A. Electrochemical impedance spectroscopy results showed the observation of the tryptophan-SCnA interaction and indicated that SC4A had the highest sensitivity to tryptophan and allowed 2.04 µg [L.sup.-1] tryptophan to be detected. Electrochemical impedance spectroscopy analysis and molecular modeling calculation confirmed that SC4A has higher tryptophan sensitivity than SC6A and SC8A. Key words: Fourier transform infrared spectroscopy, molecular modeling calculation, cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy. De nombreuses techniques ont ete axees sur la capacite des calix[n]arenes p-sulfones a former des complexes avec le tryptophane. La microscopie electronique a balayage et la spectroscopie infrarouge a transformee de Fourier ont ete utilisees pour etudier l'organisation et la structure moleculaire de differentes couches de la surface de l'electrode. Les resultats de la microscopie electronique a balayage ont montre que SC4A presentait une structure cubique alors que SC6A et SC8A possedaient des structures dendritiques. Les proprietes electrochimiques et la formation possible d'un complexe entre SCnA et le tryptophane ont ete caracterisees par voltammetrie cyclique et spectroscopie d'impedance electrochimique. Les experiences de voltammetrie cyclique ont montre que l'electrode en or etait fonctionnalisee avec succes par autoassemblage de cysteamine et de SC4A. Les resultats de la spectroscopie d'impedance electrochimique ont permis d'observer l'interaction tryptophane-SCnA et ont revele que SC4A avait une sensibilite elevee au tryptophane et qu'une concentration en tryptophane de 2,04 µg [L.sup.-1] pouvait etre detectee de cette technique d'analyse. Les calculs de modelisation moleculaire et les resultats de la spectroscopie d'impedance electrochimique ont confirme que SC4A presentait une plus grande sensibilite au tryptophane que SC6A et SC8A. [Traduit par la Redaction] Mots-cles : spectroscopie infrarouge a transformee de Fourier, calculs de modelisation moleculaire, voltammetrie cyclique, spectroscopie d'impedance electrochimique, microscopie electronique a balayage.
Introduction As the third major class of host molecules, calixarenes, (1) which are synthesized by the condensation between p-alkylphenol and formaldehyde under basic conditions, have attracted much attention due to [...]