Communication: Polymers,vith polytriacetylene (PTA) backbone (see the Figure), and also expanded radialenes (a new class of macrocycles with large conjugated all-carbon cores), are of interest because of their intrinsic two-dimensional pi-electron conjugated pathways. The synthesis, electrochemical characteristics, and linear and nonlinear optical properties of donor-functionalized polytriacetylene and donor endcapped expanded radialenes are reported and discussed.