Synthesis and Chiroptical Properties of Hydroxyphenylglycine-Based Poly(m-phenyleneethynylene-p-phenyleneethynylene)s

The polymerization of 3',5'-diiodo-4'-hydroxy-N-alpha-tert-butoxycarbonyl-D-phenylglycine ethyl-, hexyl-, and laurylamides 1-3 with p-diethynylbenzene was carried out to obtain optically active poly(m-phenyleneethynylene-p-phenyleneethynylene)s [poly(1)-poly(3)] with M-n's in the range from 6100 to 7300 in 79-82% yields. The specific rotation, CD, and UV-vis spectroscopic data revealed that poly(1)-poly(3) formed helices with predominantly one-handed screw sense. The presence of intramolecular hydrogen bonding formed between amide side groups was confirmed by solution-state IR spectroscopy. The helical structures were stable to heat and alkali metal hydroxides, while responsive to H2O and alkali metal alkoxides.