Synthesis, chiroptical properties, and photoresponsiveness of optically active poly(m -phenyleneethynylene)s containing azobenzene moieties

摘要

The Sonogashira-Hagihara coupling polymerization of 3′,5′- diiodo-4′-hydroxy-N-α-tert-butoxycarbonyl-d-phenylglycine ethyl-, hexyl-, and laurylamides 1a-c with p-nonsubstituted, cyano, hexyl, and methoxy 3,5-diethynylazobenzenes 2a-d was carried out to obtain optically active novel poly(m-phenyleneethynylene) with Mw values in the range from 6900 to 15-400 in 62-84% yields. CD and UV-vis spectroscopic data indicated that the polymers adopted thermally stable helical conformations in CH2Cl 2 and N,N-dimethylformamide. Poly(1b-2a) further formed a chirally aggregated structure. The azobenzene moieties of the polymers underwent reversible photoisomerization upon UV- and visible-light irradiation, accompanying the changes of the higher-order structures.