Acetylenic cyclophanes: emerging carbon-rich compounds for molecular construction and practical applications

The preparation of simple acetylenic 2.2]parcyclophane ‘building blocks’ is described. These compounds are readily available from the commercially available 2.2]paracyclophane employing functionalization of the parent system and conversion of the resulting functional groups into triple bonds. For the incorporation of these structures into cyclophanes with ‘extended’ π-systems, coupling reactions such as the Sonogashira or the Glaser coupling are particularly valuable. Besides addition reactions the ethynyl cyclophanes can be employed to prepare novel iron, platinum, and cobalt metal complexes. By polycondensation reactions the monomeric cyclophanes can be converted into novel polymers displaying lateral π-conjugation. The application of alkynylcyclophanes in material science and nanochemistry is discussed.