Preparation of Head-to-Tail Regioregular 6-(1-Alkenyl)-Functionalized Poly(pyridine-2,5-diyl) and its Post-Functionalization via Hydroboration

摘要

In this work, the preparation of head-to-tail regioregular poly(6-(1-tridecenyl)-pyridine-2,5-diyl) (PPy) and its post-functionalization via hydroboration is described. PPy has been prepared via Kumada-coupling polycondensation with different catalytic systems. Number-average molecular weights of up to M-n = 14.7 kDa (PDI = 2.0, DPn = 60) can be obtained, as determined by gel permeation chromatography relative to polystyrene standards. PPy has been characterized by MALDI-TOF MS, optical spectroscopy, and cyclic voltammetry. The regioregularity of the material is confirmed by comparison with a head-to-head-tail-to-tail regioregular polybipyridine (PBPy, M-n = 14.0 kDa, PDI = 1.5, DPn = 29). The 1-alkenyl-substituents in PPy have been introduced to provide functional groups for post-functionalization. Herein, it is also demonstrated that these internal double-bonds are sufficiently reactive to allow for hydroboration with 9H-borabicyclo3.3.1nonane (9H-BBN), to furnish an intermediate borylated polymer (PPyHB). Treatment of PPyHB with strong acids, and characterization of the deborylated polymer PPyH2 proves quantitative conversion of the precursor polymer.