Stabilization of Cu(i) for binding and calorimetric measurements in aqueous solutionElectronic supplementary information (ESI) available. See DOI: 10.1039/c5dt02689j

Conditions have been developed for the comproportionation reaction of Cu 2+ and copper metal to prepare aqueous solutions of Cu + that are stabilized from disproportionation by MeCN and other Cu + -stabilizing ligands. These solutions were then used in ITC measurements to quantify the thermodynamics of formation of a set of Cu + complexes (Cu I (MeCN) 3 + , Cu I Me 6 Trien + , Cu I (BCA) 2 3− , Cu I (BCS) 2 3− ), which have stabilities ranging over 15 orders of magnitude, for their use in binding and calorimetric measurements of Cu + interaction with proteins and other biological macromolecules. These complexes were then used to determine the stability and thermodynamics of formation of a 1 : 1 complex of Cu + with the biologically important tri-peptide glutathione, GSH. These results identify Me 6 Trien as an attractive Cu + -stabilizing ligand for calorimetric experiments, and suggest that caution should be used with MeCN to stabilize Cu + due to its potential for participating in unquantifiable ternary interactions. A robust method for the preparation, stabilization and delivery of Cu + for aqueous titrations, in particular ITC measurements, is described.