Mechanisms of formation of molecular complexes in protonacceptor and proton-donor solutions of butyric acide

In this work, interactions in biologically active active “butanoid (butyric) acid (BA)-acetonitrile/DMSO/pyridine/water” complexes and their spectral manifestations were studiedusing ab-ibitio calculations. When complex formation energies are calculated, this energyincreases as the number of molecules increases, but the average hydrogen bond energy correspondingto each bond does not change. Mulliken charge distributions were also analyzedthrough the optimal geometry of the molecules. Calculations showed that during the formationof complexes, the acid is formed through the atoms of the O-H and C=O, and the charge distributionin the atoms of this grouphas changed, and C=O…H, O-H…O (N) and C-H…O formationof complexes was occurred through hydrogen bonds. Also, for acids in complexesformed by DMSO/pyridine/water, the vibration bands (OH and C=O stretching vibrations) areshifted to lower frequencies, and this shift is greater for the OH vibration band than for theC=O stretching vibrations group.