Cellular uptake of protic ruthenium complexes is influenced by pH dependent passive diffusion and energy dependent efflux.

The lipophilic vs. hydrophilic properties of three protic ruthenium compounds were studied as a function of pH. Specifically, we measured Log(D) values for [(N,N)Ru(6,6'-dhbp)] complexes (where N,N = 2,2'-bipyridine (1), 1,10-phenanthroline (2), 2,3-dihydro-[1,4]dioxino[2,3-f][1,10]phenanthroline (3) and 6,6'-dhbp is the diprotic 6,6'-dihydroxy-2,2'-bipyridine ligand) from pH 4.