Data processing and analysis Data were processed using the TOPSPIN ® software. A zero filling to 32k points of the 13 C free induction signals (16k points) was applied before FFT, and spectra were baseline corrected. Resonance signals were fitted by Lorentzian functions using a homemade routine in Scilab, as in previous work. Peak integration was performed on these Lorentzian lines. Kinetic curves were fitted through the Differential Evolution algorithm, 20 also implemented in Scilab.