Electrostatic layer-by-layer deposition of photoactive dendrimers with triviologen-like cores on their surfaces. Synthesis and electrochemical and photocurrent generation measurements

The stepwise assembly of Frechet-type dendrimers with naphthalene peripheral groups and positively charged viologen-like cores on quartz and ITO surfaces utilizing the layer-by-layer approach was investigated. We were able to deposit only the (+6) charged dendrimers series on ITO. The number of assembled dendrimers was found to increase as we go to higher-generation dendrimers. This dendrimer generation effect was evident from the UV-vis and electrochemical measurements of the assembled dendrimers. The half-wave potentials (E-1/2) of the dendrimers shift to less negative values as the dendrimer generation increases in acetonitrile and to more negative values when assembled on ITO. Anodic photocurrent generation was seen upon light irradiation of the second- and third-generation dendrimers, NB1V3(+6) and NB2V3(+6), assembled on ITO but not for the zero-generation one, NV3(+6). This observation was attributed to a fast charge recombination process in NV3(+6) when compared to that of NB1V3(+6) and NB2V3(+6) dendrimers.