Spatial Structure of Tetrasubstituted Thiacalix[4]arenes Containing L-Tryptophan Fragments in Solution

Abstract

The steric structure of the cone and 1,3-alternate stereoisomers of p-tert-butylthiacalix[4]arenes bearing in the lower rim four substituents containing amide and ammonium groups as well as L-tryptophan residues was studied by ¹Н, ¹³С, ¹Н–¹Н NOESY, and ¹Н–¹³С HSQC NMR spectroscopy. The mutual repulsion of the charged ammonium groups and the presence of intramolecular hydrogen bonds in the synthesized compounds can make the peptide bond with the tryptophan residue sterically accessible for enzymes.