... Paper) RSC Adv., 2014, 4, 7959-7966. ... Fig. 3 1 H NMR spectra of the monomers. Fig. 4 shows the 13 C-NMR spectra of all the monomers. The characteristic carbon resonances of the oxazine ring are found at 49.5 and 79.1 ppm for Ar–CH 2 –N and N–CH 2 –O respectively. ...