Data were analysed with MestreNova version 5.3.3-5204 (MestreNova Research SL), running on the Ubuntu Linux distributions. The reference peak was assigned the chemical shift of 0.00 parts per million (ppm). Integral values represent the area of the aromatic region (6.9 to 7.8 ppm) relative to the TMSP reference peak; usually these integrals were linearly corrected automatically.