A vibrational molecular force field of model compounds with biological interest. VII. Harmonic dynamics of N-acetyl-α-d-muramic acid and N-acetyl-β-d-neuraminic acid in the crystalline state

Abstract

Abstract Combining a modified Urey—Bradley—Shimanouchi intramolecular potential energy function with an appropriate intermolecular energy function, normal coordinate calculations have been performed for N -acetyl-α- d -muramic acid and for N -acetyl-β- d -neuraminic acid in the crystalline state. IR and Raman spectra were recorded. Overall agreement between the observed and the calculated frequencies leads to an average error of 4 cm −1 . The computed potential energy distribution was found to be compatible with previous assignments for N -acetyl-α- d -glucoasamine for the pyranose ring and the acetamido group, and for pivalic acid for the carboxylic group. The sets of force constants used for the two monosaccharides were taken from previous works on monosaccharides.