SYNTHESIS AND CHARACTERIZATION OF -(2-(4-NITROPHENYL)ETHENYL)-1,4-PHENYLENEVINYLENE) AND A SERIES OF COPOLYMERS CONTAINING 1,4-PHENYLENEVINYLENE UNITS

-(2-(4-nitrophenyl)ethenyl)-1,4-phenylenevinylene) (PMNEPV) and a seri es of copolymers (poly(MNEPV-co-PV)) containing varying amounts of 1,4 -phenylenevinylene (PV) units have been synthesized via soluble precur sor polyelectrolytes. These polymers possess a unique structural featu re in which the electron-donating methoxy groups are located on the ph enylene rings along the main chain whereas the electron-attracting nit ro groups are attached to the side chain styryl substituents. The u.v. -vis. spectra of PMNEPV and the poly(MNEPV-co-PV)s revealed two major absorptions arising from pi-pi() transitions of the two pi-electron s ystems: the first peak is due to the pi-system in the 4-methoxy-4'-nit rostilbene moiety and the second due to the K-system in the backbone. The maximum electrical conductivity of FeCl3- or I-2-doped copolymers increased rapidly initially with the level of MNEPV unit followed by a gradual decrease when the content of MNEPV unit was > 7 mol%. The dep endence of the electrical conductivity of the present series of copoly mers, when doped either with I-2 or FeCl3, is almost the same as that observed earlier by us for methoxy-5-(2-phenylethenyl)-1,4-phenylenevi nylene) and its copolymers containing the PV unit.