Alanine-derived hosts comprising a roof-shaped carbonimide framework. Synthesis, inclusion formation and X-ray crystal structures of racemic and optically resolved free hosts, and their crystalline complexes with 3-methylcyclohexanone

Abstract

A chiral crystalline host molecule derived from the amino acid alanine comprising a characteristic 9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximide framework as an inclusion-promoting group has been synthesized in optically resolved and racemic forms and studied with regard to their inclusion behaviour. Dependent on the optical resolution state, this host forms crystalline inclusion compounds with a great variety of uncharged organic molecules ranging from protic dipolar to rather apolar compounds (78 different inclusion species) with the racemic host being more efficient. X-Ray crystal structures of the optically resolved and racemic uncomplexed host species and of their 1:1 inclusion complexes with 3-methylcyclohexanone are reported. The host hydroxy groups are always involved in O–H ⋯ OC intramolecular hydrogen bonds. The crystal packings of both complexes are analogous, showing similar cell dimensions and space groups P2₁ and P2₁/a. Moreover, the two independent molecules in the resolved complex are almost related by a pseudo centre of symmetry.