Enaminone Substituted Resorcin[4]arene-Sealing of an Upper-Rim with a Directional System of Hydrogen-Bonds

Anna Szafraniec; Marcin Grajda; Hanna Jędrzejewska; Agnieszka Szumna; Waldemar Iwanek

doi:10.3390/ijms21207494

Enaminone Substituted Resorcin[4]arene-Sealing of an Upper-Rim with a Directional System of Hydrogen-Bonds

Int J Mol Sci. 2020 Oct 11;21(20):7494. doi: 10.3390/ijms21207494.

Authors

Anna Szafraniec¹, Marcin Grajda², Hanna Jędrzejewska², Agnieszka Szumna², Waldemar Iwanek³

Affiliations

¹ Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, 60-614 Poznań, Poland.
² Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
³ Faculty of Chemical Technology and Engineering, UTP University of Science and Technology, Seminaryjna 3, 85-326 Bydgoszcz, Poland.

Abstract

The paper presents the synthesis of an enaminone resorcin[⁴]arene via a thermally activated o-quinomethide. The crystal structure indicates that in the solid state all enaminone units participate in a unidirectional seam of 12 intramolecular hydrogen bonds that are formed around the cavity. The molecule exhibits C₂ symmetry, with two opposite-laying enaminone units directed inside the cavity ("in"), and the other two units outside the cavity ("out"). In the solution the enaminone resorcin[⁴]arene exists as a mixture of conformers with distribution controlled by temperature and solvent. The experimental data are compared with the results of theoretical calculations using DFT B3LYP/6-31G(d,p) and fast semi-empirical DFTB/GFN2-xTB method in various solvents.

Keywords: DFT calculation; conformation; crystallographic structure; energy; resorcin[4]arene.

MeSH terms

Density Functional Theory
Hydrogen Bonding
Models, Molecular*
Molecular Conformation
Molecular Structure
Resorcinols / chemistry*
Spectrum Analysis

Substances

Resorcinols
resorcinol