Dendrimers have attracted much attention due to their potential applications in electronics and optoelectronics such as organic light emitting diodes and photovolatics cells. We have synthesized and characterized the electrochemical properties of conjugated dendrimers bearing phenothiazine derivatives as the peripheral group and phenylenevinylene as a core and corresponding monomer systems. We have found that the electrochemical properties and band gaps strongly depend on substituent and generation. These results can be explained in terms of pi-conjugation length changes as a function of generation.