Conformational Equilibria Landscapes: Rotational Spectroscopy and Modeling of Isolated Molecular Systems

To design drugs, molecular designers need exhaustive information on the energetic and structural factors that drive the conformational preferences at both free and bound states. These information can be inferred from structural analysis of molecule or model molecular systems. Rotational spectroscopy analysis combined to theoretical methods provide synergic approachs to investigate, in detail, the structure and internal dynamics of both isolated molecules and weakly bound complexes. In free-jet rotational spectroscopy, the experimental measurements are done by microwave spectrometers operating in the unperturbed environment of a jet plume. While the interpretation of the experimental data is performed by theoretical methods that use semi rigid and coupled Hamiltonians, ab initio and DFT calculations and flexible models. The rotational spectra are highly sensitive to the atomic masses distribution, so conformational equilibria and isotopologues species can be investigated. Regarding internal dynamics, useful information, are obtained, when hyperfine structures, are observed in the spectra. Owed to these information, it is possible to model the potential energy surface governing these motions. Furthermore, millimeter wave spectroscopy contributes significantly to the astrochemistry research area. A lot of information on circumstellar and interstellar medium results from the study of the electromagnetic radiation that reaches us. High resolution and sensitive radio-astronomy tools such as the telescopes Atacama Large Millimeter/submillimeter Array (ALMA), Herschel Space Observatory for the Far-Infrared, have been built to pick up these radiations. Laboratory rotational spectroscopy provides the basic physical parameters necessary for interpreting the astronomical spectra. During my PhD, several molecules and weakly bound complexes have been characterized using the rotational spectroscopy technique and theoretical calculations. The most of my work has been performed in the laboratory of rotational spectroscopy at UNIBO, while some objectives have been analyzed in the course of my visit at laboratory of prof. Sanz in King’s College Department in London.