A green chemistry approach to the synthesis of a crystalline organic inclusion compound

A large channel supramolecular structure composed entirely of organic molecules has been synthesised using a green chemistry approach, combining mechanochemistry and solid-state photodimerisation. Co-crystals of 1,2-bis(4-pyridyl)ethylene (bpe) and benzene-1,2,4,5-tetracarboxylic acid (bta) (stoichiometry bta·2bpe) have been obtained by solid-state grinding of a starting physical mixture. Within the resulting co-crystals, bpe molecules are crystallographically arranged such that, after UV irradiation, photodimerisation of bpe readily occurs to give a product consisting of bta and the photodimer tpcb. A large channel structure is then obtained by grinding this mixture of bta·tpcb in the presence of dimethylsulfoxide.