NMR spectra were recorded on a Bruker Avance III 300 MHz NMR spectrometer ( 1 H NMR 300 MHz) or a Bruker Avance III 400 MHz NMR spectrometer ( 1 H NMR 400 MHz) using deuterated dimethyl sulfoxide (DMSO-d6) as the solvent. Chemical shifts of protons are reported as δ in parts per million (ppm) and are relative to DMSO-d6 at δ = 2.54 ppm. Data were evaluated with the MestReNova software suite (v 12.0).