Dextran was functionalized with 6-(2,2':6',2 ''-terpyridin-4'-yloxy)-hexanoic acid using two different ratios of terpyridine to dextran, leading to terpyridine-functionalized dextran esters possessing different degrees of substitution (DS = 0.23-0.41). The intra- and intermolecular complexation behavior of both functionalized biopolymers was studied using Fe-II metal ions as well as activated Rum complexes. The complexation behavior in the first case was studied by UV visible and viscosity titration experiments. In the latter case, a water soluble comb-polymer could be obtained when using a PEG-functionalized terpyridine Ru-II moiety for complexation. Moreover, nanoprecipitation was applied to self-assemble the functionalized dextrans into nanoparticles.