25864-38-4Relevant academic research and scientific papers
Conformation of the azo bond and its influence on the molecular and crystal structures, IR and Raman spectra, and electron properties of 6-methyl-3,5-dinitro-2-[(E)-phenyldiazenyl]pyridine – Quantum chemical DFT calculations
Michalski,Bryndal,Lorenc,Hermanowicz,Janczak,Hanuza
, p. 521 - 531 (2018)
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) ? 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.
Theoretical and experimental NMR data of 3,5-dinitro-2-(2-phenylhydrazinyl) pyridine and of its 4- and 6-methyl derivatives
Wandas,Talik
, p. 15 - 27 (2013/07/05)
3,5-Dinitro-2-(2-phenylhydrazinyl)pyridine and its methyl derivatives: 4-methyl-3,5-dinitro-2-(2-phenylhydrazinyl)pyridine and 6-methyl-3,5-dinitro-2- (2-phenylhydrazinyl)pyridine were synthesized and characterized by 1H NMR and 13C NMR. Calculations were also performed where the above molecules were optimized using the methods of density functional theory (DFT) with 6-31G(d,p) and 6-311G(d,p) basis sets. For all molecules studied, the lowest energy was obtained using the 6-311G(d,p) basis set. The GIAO/DFT (Gauge Invariant Atomic Orbitals/Density Functional Theory) calculations on the 6-311G and 6-311++G and 6-311G* basis sets were carried out to determine proton and carbon chemical shifts and to find they were close to the experimental values. It has been also found that intramolecular hydrogen bonding exists between hydrogen atom (in 2-NH group) and oxygen atom (pyridine-3-NO2). Moreover, resonances between pyridine ring and electron withdrawing 3-nitro group as well between that ring and the lone electron pair of NH group favor a co-planarity of the structure; this means a chelate ring created by above-mentioned intramolecular hydrogen bond is almost co-planar with pyridine ring.
