Homologous Series of 2,5‐Diheptyloxy‐p‐Phenylene Vinylene (DHepO‐PV) Oligomers with Vinyl or 1‐Butenyl End Groups: Synthesis,Isolation, and Microstructure

In this paper we report the synthesis, isolation, and microstructure characterization of 2,5‐diheptyloxy‐p‐phenylene vinylene (PV) oligomers. Two homologous series with their chain length dependent NMR and IR spectra are presented and discussed in detail. To obtain the products, first, oligomer mixtures were synthesized by acyclic diene metathesis (ADMET) polycondensation of 2,5‐diheptyloxy‐1,4‐divinylbenzene. The Schrock‐type alkylidene complex Mo(NPhMe₂)(CHCMe₂Ph) [OCMe(CF₃)₂]₂ served as a catalyst. The polycondensation mixture was used either for the isolation of the oligomers with vinyl end groups or as a feed component for a cross metathesis reaction with 3‐hexene yielding thermally stable derivatives (investigated up to 250 °C) with 1‐butenyl end groups. From the oligomer mixtures, single oligomers up to the octamer (n = 2 … 8) were isolated by means of column chromatography. The monodispersity was determined by means of MALDI‐TOF mass spectrometry. The colors within the homologous series span widely from colorless (monomer) to yellow (trimer) to red (hexamer and upwards). The chain‐length dependence of the NMR spectra is resolved in detail. The presented data could also be used for valuable reference compounds for analogue polymer systems.

Synthesis of diheptyloxy‐PV oligomers by olefin metathesis.