Conformation of the azo bond and its influence on the molecular andcrystal structures, IR and Raman spectra, and electron properties of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine – Quantum chemical DFT calculations

Jacek Michalski , Iwona Bryndal , Jadwiga Lorenc , Krzysztof Hermanowicz , Jan Janczak , Jerzy Hanuza


The crystal and molecular structures of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine have been determined by X-ray diffraction and quantum chemical DFT calculations. The crystal is monoclinic, space group Cc (No. 9) with Z = 4 with the unit cell parameters: a = 12.083(7), b = 12.881(6), c = 8.134(3) Å and β = 97.09(5)°. The azo-bridge appears in the trans conformation in which C2-N2-N2′-C1′ torsion angle takes a value − 178.6(3)°, whereas the dihedral angle between the planes of the phenyl and pyridine rings is 3.5(2)°. The IR and Raman spectra measured in the temperature range 80–350 K and quantum chemical calculations with the use of B3LYP/6-311G(2d,2p) approach confirmed the trans configuration of the azo-bridge as the most stable energetically and allowed determination of the energy other virtual structures. The observed effects were used in the discussion of vibrational dynamics of the studied compound. The energy gap between cis and trans conformers equals to 1.054 eV (0.03873 Hartree). The electron absorption and emission spectra have been measured and analyzed on the basis of DFT calculations. The life time of the excited state is 12 μs and the Stokes shift is close to 5470 cm− 1.
Author Jacek Michalski (EaE / IChaFT / DBCh)
Jacek Michalski,,
- Department of Bioorganic Chemistry
, Iwona Bryndal (EaE / IChaFT / DBCh)
Iwona Bryndal,,
- Department of Bioorganic Chemistry
, Jadwiga Lorenc (EaE / IChaFT / DBCh)
Jadwiga Lorenc,,
- Department of Bioorganic Chemistry
, Krzysztof Hermanowicz - Institute of Low Temperatures and Structure Research Polish Academy of Sciences (INTiBS PAN) [Polish Academy of Sciences (PAN)]
Krzysztof Hermanowicz,,
, Jan Janczak - Institute of Low Temperatures and Structure Research Polish Academy of Sciences (INTiBS PAN) [Polish Academy of Sciences (PAN)]
Jan Janczak,,
, Jerzy Hanuza (EaE / IChaFT / DBCh) - [inna]
Jerzy Hanuza,,
- Department of Bioorganic Chemistry
- inna
Journal seriesSpectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, [Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy], ISSN 1386-1425, (A 30 pkt)
Issue year2018
Publication size in sheets0.5
Keywords in English6-Methyl-3,5-dinitro-2-(phenyldiazenyl)pyridine, Azo-bond conformation,Temperature dependence of IR and Raman spectra, Characteristic normal modes of the azo-bond, DFT quantum chemical calculations, Theoretical and experimental energy levels of the studied complex
ASJC Classification1602 Analytical Chemistry; 1607 Spectroscopy; 3105 Instrumentation; 3107 Atomic and Molecular Physics, and Optics
Languageen angielski
Michalski_Bryndal_Lorenc_Hermanowicz_Janczak_Hanuza_Contfirmation_Of_The_Azo_Bond.pdf 1,62 MB
Score (nominal)30
Score sourcejournalList
Publication indicators WoS Citations = 1; Scopus SNIP (Source Normalised Impact per Paper): 2017 = 1.104; WoS Impact Factor: 2018 = 2.931 (2) - 2018=2.665 (5)
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