Study of IR spectra of thiacalix[4]arene with carboxyl and adamantyl groups

Victor Furer,Ludmila Potapova,Ivan Vatsouro,Elvira Shokova,Vladimir Kovalev,E Vdovin

doi:10.1051/e3sconf/202127404002

Abstract

The IR spectra of p-(3-carboxy-1-adamantyl)thiacalix[4]arene (1) were studied. IR spectra of compound 1 do not contain bands of free hydroxyl groups. The νOH value at 3377 cm-1 signifies the formation of an intramolecular H-bond along the lower edge of compound 1. It was found that all the studied calixarene derivatives containing adamantylcarboxylic acid fragments on the upper edge form H-bonds between adjacent carboxyl groups. At the top edge of thiacalixarene, carboxyl groups form dimers or cyclic tetramers through intramolecular H-bonds. The conformation of the cone is preserved, but there is a mutual influence of Hbonds along the lower and upper edges of the thiacalixarene molecules. A structure with dimeric H-bonds between carboxyl groups is 1.5 kJ/mol less preferable than the conformation with tetrameric cyclic H-bonds of compound 1. Comparison of the νOH absorption frequency of alcohol hydroxyl groups in IR spectra of thiacalixarenes shows that the presence of the second H-bond system weakens the H-bonds of alcohol hydroxyl groups slightly.

Highlights

Calixarenes are excellent building materials for the design of new guest molecules for supramolecular chemistry [1,2,3,4,5]
Adamantyl thiacalixarenes are readily soluble in organic solvents [2]
It has been shown that carboxylated calixarenes are receptors for amines, metal ions, and aromatic hydrocarbons [8]

Summary

Introduction

Calixarenes are excellent building materials for the design of new guest molecules for supramolecular chemistry [1,2,3,4,5]. Adamantyl thiacalixarenes are readily soluble in organic solvents [2]. They have several positions for the attachment of substituents, which help to regulate the ability of molecules to form complexes. It has been shown that carboxylated calixarenes are receptors for amines, metal ions, and aromatic hydrocarbons [8]. We showed that thiacalix[4]arenes with large adamantyl substituents are in the cone conformation [9, 10]. It is known that carboxylic acids form dimers via H-bonds [11]

Methods

Discussion

Conclusion