Design and synthesis of TCNQ and DCNQI type electron acceptor molecules as precursors for ‘organic metals’

The main types of cyano-containing electron acceptor molecules, particularly those derived from TCNQ and DCNQI acceptors, have been reviewed. Ring substitution, the presence of heteroatoms and extendedπ-conjugation have been used as the principal structural modifications on the acceptor framework. Recent examples of C 60 based electron acceptors bearing an acceptor organic addend and other single-component donor–acceptor systems exhibiting semiconducting behaviour are also discussed.