NMR studies on dental adhesive monomer complete assignment of 13C-NMR spectrum and geometrical study of 5-methacryloylaminosalicylic acid.

The 13C-NMR spectrum of 5-methacryloylaminosalicylic acid (MASA), including six quarternary carbon signals, was assigned through a combination of analyses of DEPT and 2D NMR spectra such as CH-cosy and the HMBC spectrum. A computer-generated empirical prediction of the 13C-NMR chemical shifts of MASA agreed with observed values except at C1 and 2'-CH3. The geometry of the methacryloylamino portion in polar and nonpolar media seemed to differ based on analyses of the combination of two-dimensional NOE experiments and a computer simulation using molecular orbital calculations.