Appendix A.1.1. Donor Salt IPA-3DPPA

**1H-NMR** (373.2 K, DMSO-d6, 500.13 MHz, δ in ppm): 7.29–7.09 (m, 10H, Ar H), 4.47 (t, *J* = 7.7 Hz,1H, CH), 3.07 (m, *J* = 6.4 Hz, 1H, CH), 2.86 (d, *J* = 7.7 Hz, 2H, CH2), 1.05 (d, *J* = 6.4 Hz, 6H, CH3), NH3 <sup>+</sup> not given

**13C-NMR** (373.1 K, DMSO-d6, 125.76 MHz, δ in ppm): 172.8 (CO2), 144.7 (Ar), 127.7 (Ar), 127.2 (Ar), 125.4 (Ar), 46.9 (CH), 41.9 (CH2), 41.6 (CH), 23.2 (CH3)
