Hybrid macrocyclic receptors based on lower rim functionalised thiacalix[4]arene and amino acids: Synthesis, structure and binding properties towards metal ions

Abstract

Peptidothiacalixarene derivatives 4a-d and 7a-d have been synthesized in excellent yields by the reaction of methyl esters of glycine, L-alanine and D- and L-phenyl alanine with lower rim substituted 1, 3-diacid chloride and tetraacid chloride derivatives of thiacalixarene. The conformational and hydrogen bonding properties of these conjugates have been investigated by means of (1)H NMR in the solution state and by X-ray crystallography in the solid state. Complexation studies performed by UV-Vis and (1)H NMR spectroscopy in acetonitrile solution show that the 1,3-disubstituted hybrids selectively bind Hg(2+) ions and the orientation of the substituent on the chiral carbon is found to have a significant effect on the binding.