Synthesis of Well-Defined Oligo(2,5-dialkoxy-1,4-phenylene vinylene)s by Combined Olefin Metathesis and Wittig-type Coupling: Effect of Conjugation Repeat Units and End Groups Toward Optical Properties

摘要

Defect-free, highly trans oligo(2,5-dialkoxy-1,4-phenylene vinylene)s [alkoxy = O(CH_2)_2 OSi~i Pr_3] with both repeat units (ex. 9, 15, and 31 repeat units) and end groups (aldehyde, C_6 F_5, terthiophene, ferrocene) well-defined are prepared by a stepwise combined olefin metathesis using Mo(CHCMe_2 Ph)(N-2,6-Me_2C_6H_3)[OCCH_3 (CF_3)_2]_2 with subsequent Wittig-type coupling. End-functionalized oligomers with uniform distributions are also prepared by acyclic diene metathesis (ADMET) condensation using a ruthenium-carbene catalyst, followed by the above combined olefin metathesis and Wittig coupling. The effects of the repeat units and the end functional groups on the optical properties are explored; the photoluminescence quantum yields in the end-functionalized oligomers (e.g., 9 mers) are affected by the end groups.