Dissection of the Factors Affecting Formation of a CH∙∙∙O H-Bond. A Case Study

Quantum calculations are used to examine how various constituent components of a large molecule contribute to the formation of an internal CH···O H-bond. Such a bond is present in the interaction between two amide units, connected together by a series of functional groups. Each group is removed one at a time, so as to monitor the effect of each upon the H-bond, and thereby learn the bare essentials that are necessary for its formation, as well as how its presence affects the overall molecular structure. Also studied is the perturbation caused by change in the length of the aliphatic chain connecting the two amide groups. The energy of the CH···O H-bond is calculated directly, as is the rigidity of the entire molecular framework.