Observation of an incoherent thermally activated proton hopping process in calix-[4]-arene by means of anelastic spectroscopy

TL;DR

This study uses anelastic spectroscopy to observe thermally activated proton hopping in calix[4]-arene, revealing insights into atomic motion within molecules at a mesoscopic scale.

Contribution

It demonstrates the effectiveness of anelastic spectroscopy in detecting and analyzing proton hopping processes in calix[4]-arene.

Findings

Detected three thermally activated peaks in the spectrum.

The lowest temperature peak is linked to proton hopping of OH groups.

Anelastic spectroscopy proves useful for studying atomic motions in molecules.

Abstract

The anelastic spectrum of calix[4]arene was measured at two different vibrational frequencies. Three thermally activated peaks were detected. The lowest temperature peak can be described considering a continous distribution function of activation energies for the relaxation. This anelastic peak can be ascribed to a thermally activated hopping process of H atoms of the OH groups, corresponding to a flip-flop of the OH bond. From the results of the present study, it seems that anelastic spectroscopy is a good experimental technique to study atomic motion inside molecules at a mesoscopic (few molecules) level.