Aromaticity effect on supramolecular aggregation. Aromatic vs. cyclic monohydroxy alcohols

N Soszka; B Hachuła; M Tarnacka; J Grelska; K Jurkiewicz; M Geppert-Rybczyńska; R Wrzalik; K Grzybowska; S Pawlus; M Paluch; K Kamiński

doi:10.1016/j.saa.2022.121235

Aromaticity effect on supramolecular aggregation. Aromatic vs. cyclic monohydroxy alcohols

Spectrochim Acta A Mol Biomol Spectrosc. 2022 Aug 5:276:121235. doi: 10.1016/j.saa.2022.121235. Epub 2022 Apr 6.

Authors

Affiliations

¹ Institute of Chemistry, Faculty of Science and Technology, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland; Institute of Physics, Faculty of Science and Technology, University of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland.
² Institute of Chemistry, Faculty of Science and Technology, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland. Electronic address: barbara.hachula@us.edu.pl.
³ Institute of Physics, Faculty of Science and Technology, University of Silesia in Katowice, 75 Pułku Piechoty 1, 41-500 Chorzów, Poland.
⁴ Institute of Chemistry, Faculty of Science and Technology, University of Silesia in Katowice, Szkolna 9, 40-006 Katowice, Poland.

PMID: 35429862
DOI: 10.1016/j.saa.2022.121235

Abstract

In this paper, the steric hindrance effect related to the presence of either a cyclic or aromatic ring on the self-association process in the series of monohydroxy alcohols (MAs), from cyclohexanemethanol to 4-cyclohexyl-1-butanol and from benzyl alcohol to 4-phenyl-1-butanol, was studied using X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared (FTIR) spectroscopy, Broadband Dielectric Spectroscopy (BDS) and the Pendant Drop (PD) methods. Based on FTIR results, it was shown that phenyl alcohol (PhA) and cyclohexyl alcohol (CA) derivatives reveal substantial differences in the association degree, the activation energy of dissociation, and the homogeneity of supramolecular nanoassociates suggesting that the phenyl ring exerts a stronger steric impact on the self-assembling of molecules than cyclohexyl one. Additionally, XRD data revealed that phenyl moiety introduces more heterogeneity in the organization of molecules compared to the cyclic one. The changes in the self-association process of alcohols were also reflected in differences in the molecular dynamics of the H-bonded aggregates, as well as in the Kirkwood factor, defining the long-range correlation between dipoles, which were slightly higher for CAs with respect to those determined for PhAs. Unexpectedly it was also found that the surface layers of PhAs were more organized than those formed by CAs. Thus, these findings provided insight into the impact of aromaticity on the self-assembly process, H-bonding pattern, supramolecular structure, and intermolecular dynamics of the studied alcohols.

Keywords: Aromaticity; Cyclohexyl alcohols; Phenyl alcohols; Self-association; Steric hindrance.