Alkyl chain length tunes the reversion temperature of mechanofluorochromic phenylene-ethynylenes that show reversible force-induced change of fluorescence from green to orange.

Understanding and manipulating crystal polymorphism can provide novel strategies for materials discovery in organic optoelectronics.

Synthesis of sheet-coil-helix and coil-sheet-helix triblock copolymers by combining ROMP with palladiummediated isocyanide polymerization. Polym. Chem. 2018, 9, 5655−5659. 2 The termination of ROMPgenerated diblock copolymers with a palladium-f unctionalized vinyl ether allowed for chain extension with isocyanides.

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.

This contribution describes the synthesis of an unsymmetrical substituted tetraalkoxy[2.2]paracyclophane-1,9-diene comprised of an ortho-substituted and a para-substituted dioctyloxybenzene. (S p )-4,5,12,15-tetraoctyloxy-[2.2]paracyclophane-1,9diene ((S p )-pCpd) and (R p )-4,5,13,16-tetraoctyloxy-[2.2]paracyclophane-1,9-diene ((R p )-pCpd) are formed as planar chiral enantiomers. Unlike other tetraalkoxy-substituted pCpds that form as diastereomers, both the (S p )-pCpd and the (R p )-pCpd can be polymerized via ring-opening metathesis polymerization (ROMP) using Grubbs' third generation initiator (G3) as it is achiral. Living ROMP afford copolymers featuring alternating cis,trans-poly(p-phenylenevinylene)s (PPV)s. The polymers' unique, blueshifted optical properties are due to the alkoxy-substitution in the polymer's backbone and the resulting materials could be photoisomerized to the all-trans polymer. This strategy affords tetraalkoxy-pCpd monomers in high yields for the polymerization of soluble PPVs with low or narrow dispersities.