The relative lipophilicities (or distribution coefficient, D, at pH = 7.4) of the complexes were determined using a modified “shake flask” method as described in previous work.65 (link) A saturated solution of 1-octanol with water was prepared by mixing 16 mL of 1-octanol (99.9%) with 4 mL of 10 mM PBS. A saturated solution of PBS with 1-octanol was prepared by mixing 16 mL of PBS with 4 mL of 1-octanol. The saturated solutions were shaken for 24 h at ambient temperature (≈22 °C) using a New Brunswick Classic C25KC Incubator Shaker set at 230 rpm before further use. Starting with 500 μL of 50 μM complex (chloride salt) prepared in saturated 1-octanol, an equal volume of saturated water was added to give a total volume of 1 mL. The mixtures were shaken 200 times, centrifuged at 11 000 rpm (≈10 000 × g) for 2 minutes using a BioRad Model 16K Microcentrifuge; the two resultant layers were then separated with a syringe. The concentrations of the complexes in both octanol and water layers were calculated from absorption measurements using a microplate reader (SpectraMax M2e) and standard curves in each solvent.