Geometrically pure, all-cis poly (phenylene vinylenes)(PPVs) are synthesized by Suzuki- Miyaura-type polycondensation of 2, 5-dioctyloxy-1, 4-benzenediboronic acid with (Z, Z)-bis (2-bromoethenyl) benzenes, which are prepared by ruthenium-catalyzed (Z)-selective double hydrosilylation of diethynylbenzenes, followed by bromodesilylation of the resulting (Z, Z)-bis (2-silylethenyl) benzenes with N-bromosuccinimide. The all-cis PPVs thus ...