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Syntheses are described for optically active oligomers 9 and 27. The steps required have three essential features. (1) A bromine directs a photocyclization, blocking both the position it occupies and the one adjacent. (2) An acid scavenger (propylene oxide) prevents benzylic ethers from being eliminated during photocyclization. (3) The stereogenicity of one carbon controls the direction in which the helix winds. The oligomers are the first to be prepared in which metallocenes are joined by conjugated systems of double bonds. Their optical activity is very high. The cyclic voltammogram of 9 shows two cathodic waves whose closeness implies that the interaction between adjacent units is weak. When 9 is reduced electrochemically on Pt, a film of neutral oligomers is produced. This film is conductive, and it catalyzes charge transfer. Its weight, measured using a quartz crystal microbalance after the amount of reduction was analyzed coulometrically, measured the molecular weight of 9.

The title composition, isoPEK, was prepared from 4-fluoro-3‘-hydroxybenzophenone in N-methylcaprolactam at 225 °C. Cyclomer formation interfered with polymerization at lower temperatures in alternative solvents and dominated in dilute solutions. The 50/50 to 70/30 copolymers of PEK and isoPEK were prepared using 4-fluoro-4‘-hydroxybenzophenone. An analogous composition, poly(oxy-1,3-phenylenecarbonyl-1,4-phenyleneoxy-1,4-phenylenecarbonyl-1,4-phenylene) or isoPEKEK, was prepared from 4,4‘-difluorobenzophenone and 3,4‘-dihydroxybenzophenone using similar conditions. Thermal crystallization of the copolymers was successful, but isoPEK and isoPEKEK were only capable of solvent-induced crystallization. The semicrystalline materials were studied by thermal analysis and X-ray diffraction. The copolymers melted at 264−307 °C and possessed random microstructures with isomorphic crystallization of the PEK and isoPEK repeat units. IsoPEK and isoPEKEK melted, respectively, at the low temperatures of 180 and 193 °C. IsoPEK crystallized with both Form 1 and Form 2 unit cells, while isoPEKEK and the copolymers crystallized with the Form 1 unit cell. IsoPEK was also prepared by ring-opening polymerization of its cyclomers in the melt using cesium fluoride as catalyst. The 3,4‘ catenation of the isoPEK repeat unit and the related monomers was used to rationalize the unique chemistry and properties of these polymers.

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