Structural characterization and some coordinational aspects of tetrathiacalix[4]arenes functionalized by hydrazide groups

The structural peculiarities of tetrathiacalix[4]arenes with acetylhydrazide substitutes in cone and 1,3-alternate conformations have been determined by means of X-ray analysis, IR and NMR spectroscopy. The structural and molecular modeling data were used in the interpretation of binding properties of calix[4]arene tetrahydrazides. The quantum-chemical calculations at the DFT level using the PBE exchange-correlation functional were performed for the complexation of 1,3-alternate conformer of tetrathiacalix[4]arene with Ag+ ion. It was shown that the removal of tert-butyl groups from tert-butyltetrathiacalix[4]arene platform facilitates a bis-ligand coordination of the metal ion and leads to a remarkable increase of Ag+ extraction efficiency.