Molecular structure and spectroscopic properties of the complex of N-methylmorpholine betaine with 3,4-dinitrophenol

The molecular structure of the complex of N-methylmorpholine betaine with 3,4-dinitrophenol has been determined by X-ray diffraction. The crystals are monoclinic, space group P21/c. The intermolecular OHO hydrogen bond is short, with the O⋯O distance of 2.471(2) Å. The morpholine ring adopts a chair conformation with the CH3 group in the equatorial position and the CH2COO− substituent in the axial one. The optimized geometry of the complex investigated at the B3LYP/6-31G(d,p) approach is consistent with that in the crystal. The FTIR spectrum confirms the presence of a short asymmetric hydrogen bond. The UV, 1H and 13C NMR spectra have been analyzed to elucidate the complex structure in solution.