Work

Structural Diversity of Tetra- O -ethyl- p - tert- butylcalix[4]arene and a Desolvation-Induced Symmetry-Breaking Single-Crystal to Single-Crystal Transformation with Z′ Doubling

Year: 2026

Type: article

Abstract: The crystal structures of three distinct conformers of tetra- O -ethyl- p - tert- butylcalix[4]arene have been revealed, namely cone ( 1 ), partial cone ( 2a and 2b ), and 1,2-alternate ( 3a, 3b, 3c ). The polymorphs 2a and 2b differ in whether tert -butyl or ethoxy groups engage in the intermolecular C–H···π contacts that dominate the packing. Two solvates of the 1,2-alternate conformer, 3a and 3c, were obtained from acetonitrile and chloroform, respectively. The acetonitrile molecules were removed in a single-crystal to single-crystal fashion from 3a, resulting in the solvent-free phase 3b . This irreversible transition causes the loss of the inversion center present in the solvated phase (monoclinic, P 2 1 / c ), connected with a doubling of Z′, and generates a noncentrosymmetric lattice (orthorhombic, P 2 1 2 1 2 1 ). Moreover, desolvation of the chloroform solvate ( 3c ), crystallizing in a triclinic system, leads to the same desolvated 3b phase, indicating the stability of the latter. The studies on the polymorphs as well as the desolvation-induced transformations were supported by investigations on bulk material, applying PXRD and TGA/DTA. Furthermore, a crystal structure containing two conformers, the partial cone and 1,2-alternate conformation, was also revealed ( 4 ).

Source: Crystal Growth & Design

DOI: 10.1021/acs.cgd.5c01682

Authors: Renny Maria Losus, Marek P. Krzemiński, Liliana Dobrzańska

Institution: Nicolaus Copernicus University

Language: English

Topic: Supramolecular Chemistry and Complexes

Subfield: Organic Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funder: Narodowe Centrum Nauki