Influence of pH on the speciation of copper(II) in reactions with the green tea polyphenols, epigallocatechin gallate and gallic acid

► Cu(II) speciation with two polyphenols (EGCG and GA) at different pH. ► EPR study at two frequencies (X- and S-band). ► Polymerisation dominates at slightly acidic and neutral pH. ► Complexation dominates above neutral pH.