Synthesis of N,N′-bis(9-phenylxanthen-9-yl)ethylenediamine and an investigation of its host–guest inclusion potential

Abstract

The novel amine, N,N′-bis(9-phenylxanthen-9-yl)ethylenediamine 1, was synthesized by treating 9-phenylxanthen-9-ylium perchlorate with ethylenediamine. Its host potential was assessed by allowing it to crystallise from a range of organic solvents (single and binary mixtures), of which several were found to be included. The stoichiometries of these host–guest complexes were determined through 1H-NMR analysis and their stabilities assessed through thermal analysis. Single crystal X-ray crystallography was used to elucidate the crystal structure of the 1∶1 1·THF inclusion complex. It was found that only one of the two amine moieties of the host functions as a donor, forming a nearly linear hydrogen bond to the oxygen atom of the guest molecule. Each THF molecule is effectively surrounded by host molecules so that the THF molecules are found to occupy discrete “cavities” within the host lattice. The activation energy associated with desolvation of the 1·THF complex was determined through thermal analysis and was found to decrease as desolvation progressed.