Cyclophanediene and Cyclophanetriene-Based Conjugated Polymers

Poly(p-phenylene vinylene)s (PPVs) and poly(arylene vinylene)s are key materials for a variety of applications ranging from organic light emitting diodes to fluorescent optical probes. Their syntheses, however, have been hampered by non-living or step-growth polymerization techniques. The development of functional-group tolerant olefin metathesis catalysts has enabled the use of living ring-opening metathesis polymerization (ROMP) of cyclophane monomers yielding PPVs and poly(p-phenylene-co-arylene vinylene)s in a living manner. Low dispersity and soluble PPVs are afforded with control over the number of repeat units with easy incorporation of different end-groups at their heads or tails. In this review, a comprehensive overview of tetrasubstituted and disubstituted alkyl and alkoxy containing [2.2]paracyclophane-1,9-diene, [2.2]metaparacyclophane-1,9-diene, [2.2.2]paracyclophane-1,9,17-triene, and benzothiadiazole-[2.2]paracyclophane-1,9-diene is provided. The high ring strain of these monomers enables efficient polymerizations with ruthenium initiators. A particular emphasis is on [2.2]paracyclophane-1,9-dienes as it is the most investigated class of polymerized cyclophanediene since initially reported 30 years ago. Additionally, applications for soft materials synthesized by ROMP are examined, highlighting easily accessed PPV copolymers and PPV block copolymers that can be phototriggered, as well as PPVs featuring supramolecular recognition units installed at their termini to afford orthogonally self-assembled architectures.