Synthesis and nonlinear optical properties of 1,3- and 1,4-disubstituted type of poly(phenyleneethynylene)s containing electron-donor and acceptor group

The third-order nonlinear optical properties of 1,3-and 1,4-disituted poly (phenyleneethynylene)s containing electron-donor and accpetor groups were investigated in terms of the local polirization effect. The electron-donor and acceptor groups being set apart in the benzene ring adjacent to the triple bond in 1,4-disusbstituted poly (phenyleneethynylene)s was found to increase the X (3) value, together with the shift of the maximum absorption to longer wavelengths, while no significant effect was observed in the X (3) value for 1,3-disubstituted poly (phenyleneethynylene)s having both electron-donor and acceptor groups present in a benzene ring, in accordance with the fact that the maximum absorption remains at shorter wavelength.