Ethanolamine: conformational diversity

Abstract

Nonempirical stationary calculations in combination with Born–Oppenheimer molecular dynamics simulations, both carried out at the MP2/6-31++G(d,p) level, shed light on the relative probability of either stationary or temperature-dependent dynamic formation of different isomers of monoethanolamine molecule. Thermal excitation of certain intramolecular vibrations substantially affects the origination and lifetimes of isomers, which cannot be predicted on the basis of time-independent calculations solely. Trans and gauche orientations of amino and hydroxyl groups are interdependent to a certain degree, and with an increase in temperature and duration of evolution, the formation of N–H…O hydrogen bond becomes progressively more likely, despite the energetic preferability of O–H…N bond.