Cooperative Hydrogen Bonding, Molecular Electrostatic Potentials, and Spectral Characteristics of Partial Thia-Substituted Calix[4]arene Macrocycles.

Abstract

Structure and spectral characteristics of the 2,14-dithiacalix[4]arene and its homooxa derivatives are obtained employing the dispersion-corrected ωB97X-D-based density functional theory. The conformational behavior of these receptors is governed by the nature and number of substituents at the bridging positions. The partial thia-substituted calix[4]arene scaffolds reveal the electron-rich regions reside near heteroatoms which emerge with deeper minima in molecular electrostatic potential topography. Underlying cooperativity of intramolecular hydrogen bonding manifests in characteristic OH vibrations of their infrared spectra. Moreover, the (1)H NMR reveals that hydrogen-bonded protons are deshielded, unlike those from tertiary butyl substituents. These inferences are in agreement with the experimental data.