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Front. Chem. | doi: 10.3389/fchem.2018.00025

Rotational Spectrum and Conformational Analysis of N-methyl-2-aminoethanol: Insights into the Shape of Adrenergic Neurotransmitters

 Sonia Melandri1*,  Assimo Maris1, Camilla Calabrese1, 2,  Luca Evangelisti1, Anna Piras1 and Valentina Parravicini1
  • 1Dipartimento di Chimica "G. Ciamician", Università di Bologna, Italy
  • 2Dpto. Química Física, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV/EHU), Spain

Abstract
We describe an experimental and quantum chemical study for the accurate determination of the conformational space of small molecular systems governed by intramolecular non-covalent interactions. The model systems investigated belong to the biological relevant aminoalcohol’s family, and include 2-aminophenylethanol, 2-methylaminophenylethanol, noradrenaline, adrenaline 2-aminoethanol and N-methyl-2-aminoethanol. For the latter molecule, the rotational spectrum in the 6-18 and 59.6-74.4 GHz ranges was recorded in the isolated conditions of a free jet expansion. Based on the analysis of the rotational spectra, two different conformational species and 11 isotopologues were observed and their spectroscopic constants, including 14N-nuclear hyperfine coupling constants and methyl internal rotation barriers, were determined. From the experimental data a structural determination was obtained, which was also used to benchmark accurate quantum chemical calculations on the whole conformational space. Atom in molecules and non-covalent interactions theories allowed the characterization of the position of the intramolecular non-covalent interactions and the energies involved, highlighting the subtle balance responsible of the stabilization of all the molecular systems.

Keywords: Rotational spectroscopy, quantum chemical calculations, atom in molecules theory, molecular structure, hydrogen bond, N-methyl-2-aminoethanol, 1, 2-Aminoalcohols, adrenergic neurotransmitters.

Received: 19 Dec 2017; Accepted: 31 Jan 2018.

Edited by:

Kevin K. Lehmann, University of Virginia, United States

Reviewed by:

Jesus Perez Rios, Purdue University, United States
Mark D. Marshall, Amherst College, United States
George C. Shields, Furman University, United States  

Copyright: © 2018 Melandri, Maris, Calabrese, Evangelisti, Piras and Parravicini. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Sonia Melandri, Università di Bologna, Dipartimento di Chimica "G. Ciamician", via Selmi, 2, Bologna, I-40126, Italy, sonia.melandri@unibo.it