Six new crystalline clathrates of cyclotricatechylene (CTC) including two donor-acceptor complexes

Dark blue [CTC](2)center dot(TCNE)center dot 6THF and dark green [CTC](2)center dot(TCNQ)center dot 4THF are both exclusion complexes, with the cyanoalkene acceptor being sandwiched between the catechol rings of two cyclotricatechylene (CTC) host molecules. There is also extensive hydrogen bonding between the CTC and tetracyanoethene (TCNE) or tetracyanoquinodimethane (TCNQ) molecules, which is unusual for crystals containing these cyanoalkenes. Crystallographic, IR and UV-vis data show that these are typical donor-acceptor complexes, with strong charge-transfer interactions between the CTC and cyanoalkene acceptors. These are the first donor-acceptor complexes of a cyclotriveratrylene (CTV)-derived host, and the first crystallographically characterised adducts between TCNE or TCNQ and an organic cavitand. The solvate CTC center dot 3.5THF center dot 0.5H(2)O adopts a novel nanoporous crystal lattice, composed of undulating hydrogen-bonded sheets of CTC molecules. In contrast, the clathrates CTC center dot 2EtOH, CTC center dot 3DMA and CTC center dot 5DMSO all adopt structures that are related to previously reported clathrates of CTC, containing hydrogen-bonded bilayers or bis-monolayers of CTC molecules. The CTC molecules in all six structures contain included guest solvent. This contrasts with CTV clathrate crystals, which rarely contain included solvent.