pH-dependent binding of guests in the cavity of a polyhedral coordination cage: reversible uptake and release of drug molecules† †Electronic supplementary information (ESI) available: Experimental information; further details on the NMR titrations used to measure binding constants at different pH values; crystallographic data in CIF format (CCDC 1013340). See DOI: 10.1039/c4sc02090a Click here for additional data file. Click here for additional data file.

For all host/guest binding experiments samples were prepared as follows. Host solution: the host cage (16 mg) was dissolved in 10 ml D2O to make a 0.2 mM stock solution. Guest solutions: the guests were individually dissolved in 5 ml of the host solution (to keep the host concentration constant during the titration); the mass used varied with the desired concentration. All binding experiments were performed three separate times; the values for binding constants quoted are the average of the three measurements with the error quoted being two standard deviations from the mean.