The existence of the O−H∙∙∙O hydrogen bond present at dimer of water increases the stability of O−H∙∙∙O and C−H∙∙∙O hydrogen bonds in the ternary complexes compared to relevant binary complexes. By vibrational and NBO analyses, it is found that the magnitude of stretching frequency red shift of O−H bonds in the O−H∙∙∙O hydrogen bonds is enhanced, whereas the extent of stretching frequency blue shift of C−H bonds in the C−H∙∙∙O hydrogen bonds is weakened when the cooperativity of hydrogen bonds happens in the ternary complexes. | Vietnam Journal of Chemistry, International Edition, 55(5): 578-584, 2017 DOI: A thoroughly theoretical investigation into complexes formed by interaction of dimethyl sulfoxide with two water molecules Pham Ngoc Khanh, Nguyen Thi Viet Nga, Nguyen Tien Trung* Laboratory of Computational Chemistry and Modelling, Department of Chemistry, Quy Nhon University Received 14 April 2017; Accepted for publication 20 October 2017 Abstract A computational study of the stability and the cooperative effect of hydrogen bonds in the complexes of dimethyl sulfoxide and two water molecules was undertaken at the MP2/6-311++G(2d,2p) level of theory. The cooperative energies of obtained complexes are significantly negative, indicating that there is a large cooperativity between types of hydrogen bonds. The existence of the O−H∙∙∙O hydrogen bond present at dimer of water increases the stability of O−H∙∙∙O and C−H∙∙∙O hydrogen bonds in the ternary complexes compared to relevant binary complexes. By vibrational and NBO analyses, it is found that the magnitude of stretching frequency red shift of O−H bonds in the O−H∙∙∙O hydrogen bonds is enhanced, whereas the extent of stretching frequency blue shift of C−H bonds in the C−H∙∙∙O hydrogen bonds is weakened when the cooperativity of hydrogen bonds happens in the ternary complexes. Obtained results of AIM analysis and stabilization energies indicate the larger contribution of the O−H∙∙∙O relative to the C−H∙∙∙O hydrogen bond to cooperativity. Keywords. Dimethyl sulfoxide, hydrogen bond, cooperativity. 1. INTRODUCTION Noncovalent bonding interactions play an important role in crystal packing, molecular recognition, biological processes, and reaction selectivity [1, 2]. Understanding these interactions is thus essential for unraveling the mysteries of cellular function in health and disease as well as developing new drugs and materials that serve human life [3]. Among them, the subject of hydrogen bond A−H∙∙∙B can
