Synthesis, chiroptical properties of a helical polyacetylene derivative carrying urea moieties

A novel phenylacetylene derivative containing urea groups was synthesized and polymerized with a Rh catalyst to give the corresponding polymer, poly( 1 ) with moderate number-average molecular weights. The poly( 1 ) was soluble in toluene, CHCl 3 , CH 2 Cl 2 , THF, DMF, and DMSO, but insoluble in hexane, diethyl ether and MeOH. The specific rotation and circular dichroism (CD) spectroscopic studies revealed that poly( 1 ) took predominantly one-handed helical structures. The presence of intramolecular hydrogen bonding was confirmed by liquid-state IR spectroscopy. The helicity of poly( 1 ) could be tuned by temperature and anion. The helical conformation of the polymer was stable against Br- but susceptible to F − .