Crystal structure, vibrational and optic properties of 2-N-methylamino-3-methylpyridine N-oxide - Its X-ray and spectroscopic studies as well as DFT quantum chemical calculations

I Bryndal; J Lorenc; L Macalik; J Michalski; W Sąsiadek; T Lis; J Hanuza

doi:10.1016/j.molstruc.2019.05.064

Crystal structure, vibrational and optic properties of 2-N-methylamino-3-methylpyridine N-oxide - Its X-ray and spectroscopic studies as well as DFT quantum chemical calculations

J Mol Struct. 2019 Nov 5:1195:208-219. doi: 10.1016/j.molstruc.2019.05.064. Epub 2019 May 24.

Authors

I Bryndal¹, J Lorenc², L Macalik³, J Michalski², W Sąsiadek², T Lis⁴, J Hanuza³

Affiliations

¹ Department of Drugs Technology, Faculty of Pharmacy with Division of Laboratory Diagnostics, Wroclaw Medical University, Borowska 211A, 50-556, Wrocław, Poland.
² Department of Bioorganic Chemistry, Institute of Chemistry and Food Technology, Faculty of Engineering and Economics, Wrocław University of Economics, Komandorska 118/120, 53-345, Wrocław, Poland.
³ Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422, Wrocław, Poland.
⁴ Faculty of Chemistry, University of Wroclaw, Joliot-Curie Street 14, 50-383, Wrocław, Poland.

Abstract

The crystal and molecular structure and physicochemical properties of 2-N-methylamino-3-methylpyridine N-oxide (MA3MPO) have been studied. MA3MPO was synthesized from 2-amino-3-methylpyridine by several steps to form colorless crystals suitable for crystallographic analysis. The data reveal that MA3MPO crystallizes in the monoclinic space group P2₁/n. The studied compound contains a nearly flat triply substituted pyridine skeleton whose structure is stabilized by an intramolecular N-H⋅⋅⋅O hydrogen bond. The N-oxide molecules are connected together by weak C-H⋯O hydrogen bonds, an acceptor of which is the oxygen atom from the N-oxide group. This leads to creation of two-dimensional network of hydrogen bonds. Its IR, Raman, UV-Vis and luminescence spectra have been measured and analyzed on the basis of DFT and NBO quantum chemical calculations in which the B3LYP/6-311++G(d,p) approach was applied. The distribution of the electron levels in the studied compound has been analyzed in terms of the possibility of its participation in the ligand-to-lanthanide ion energy transfer.

Keywords: 2-N-Methylamino-3-methylpyridine N-oxide; Crystal structure; IR; NBO and DFT calculations; Raman; Synthesis; UV–Vis and luminescence spectra.