ABSTRACT
Recent rapid development of methodologies for constructing dendritic architectures has enabled the synthesis of a number of nanometer-sized molecular particles with well-defined composition [1-3]. Among modern trends to integrate various functionalities into nano-sized molecules, those for potential light-harvesting devices have attracted interest [4]. Since artifi cial light-harvest would require absorption of incident visible light by peri pheral multi-antenna components and efficient channeling of the excitation energy to a common focal component, an important factor to be considered, particularly for the basic research, appears to be the rigidity of the system [5,6]. When the geometry of the dendrimer is strictly defined, the photo physical results obtained can be more easily compared with theoretical predictions than those of systems with flexible arms and undefined struc tures. Further, it is desirable for the number of antenna units at periphery to be large in order to achieve high capture efficiency of photons. Good examples which satisfy these requirements are metallodendrimers synthe sized by Balzani’s group [7] and others [8,9], which consist of M(2,3-dpp) (M = Ru(II) and Os(II), dpp = bis(2-pyridyl)pyrazine) or similar networks with estimated particle size of 5 nm. As in these cases, Ru(II)-polypyridine type complexes are excellent candidates for chromophor components because of their outstanding excited states characteristics in the visible region.
