A disubstituted acetylene with both polar and conjugate groups

phenylpropiolic acid (PhPA)

was directly polymerized into poly(phenylpropiolic acid) oligomer through metathesis polymerization with Pd(PPh3)2Cl2 as catalyst and toluene as solvent

while the monomer PhPA was synthesized by the addition reaction of cinnamic acid with bromine and the followed elimination of hydrogen bromide.The polymerizations of PhPA showed a moderate yield of oligomer at 75℃ and in toluene solvent.The structures of both PhPA and oligomer were confirmed by IR and 1H-NMR.For example

the absorption band at 1620 cm-1 associating with CC stretching appears in the spectrum of oligomer

instead of 2210 cm-1 associating with CC stretching in the spectrum of PhPA.The oligomer is soluble in common polar solvents and has high thermal stability.Comparison of the absorption spectra of the oligomer with its monomer reveals that the absorption of the oligomer in the spectral region beyond 310 nm is associated with the electronic transitions of oligomer skeleton.On the fluorescence investigation of the oligomer

THF solutions of oligomer emit blue light and show the peak emissions at 420 nm at different concentrations when excited at 342 nm.At the concentration of 004 mmol/L of oligomer

its emission indicates the biggest intensity.