Delivering potential theranostic metal complexes into preferential cellular targets is becoming of increasing interest. Here we report that nuclear uptake of a cell-impermeable DNA "light-switching" Ru(II)-polypyridyl complex can be significantly facilitated by chlorophenolate counter-anions, which was found, unexpectedly, to be correlated positively with the binding stability but inversely with the lipophilicity of the formed ion pairs.