The LAM of the Rings: Large Amplitude Motions in Aromatic Molecules Studied by Microwave Spectroscopy |
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Authors: | Ha Vinh Lam Nguyen Walther Caminati Jens-Uwe Grabow |
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Affiliation: | 1.Univ Paris Est Creteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France;2.Institut Universitaire de France (IUF), F-75231 Paris, France;3.Departimento di Chimica ‘G. Ciamican’, Universita degli Studi di Bologna, Via Selmi 2, 40126 Bologna, Italy;4.Institut für Physikalische Chemie und Elektrochemie, Gottfried-Wilhelm-Leibniz-Universität Hannover, Callinstraße 3A, 30167 Hannover, Germany |
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Abstract: | Large amplitude motions (LAMs) form a fundamental phenomenon that demands the development of specific theoretical and Hamiltonian models. In recent years, along with the strong progress in instrumental techniques on high-resolution microwave spectroscopy and computational capacity in quantum chemistry, studies on LAMs have become very diverse. Larger and more complex molecular systems have been taken under investigation, ranging from series of heteroaromatic molecules from five- and six-membered rings to polycyclic-aromatic-hydrocarbon derivatives. Such systems are ideally suited to create families of molecules in which the positions and the number of LAMs can be varied, while the heteroatoms often provide a sufficient dipole moment to the systems to warrant the observation of their rotational spectra. This review will summarize three types of LAMs: internal rotation, inversion tunneling, and ring puckering, which are frequently observed in aromatic five-membered rings such as furan, thiophene, pyrrole, thiazole, and oxazole derivatives, in aromatic six-membered rings such as benzene, pyridine, and pyrimidine derivatives, and larger combined rings such as naphthalene, indole, and indan derivatives. For each molecular class, we will present the representatives and summarize the recent insights on the molecular structure and internal dynamics and how they help to advance the field of quantum mechanics. |
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Keywords: | rotational spectroscopy aromatic rings internal rotation inversion tunneling coupled large amplitude motions |
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