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.
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•The 2-N-methylamino-3-methylpyridine N-oxide (MA3MPO) was synthesized and characterized.•The studied compound structure is stabilized by an intramolecular N–H⋯O hydrogen bond.•The molecules are connected together by weak C–H⋯O hydrogen bonds.•The amino group plays the role of effective hydrogen-bond donor but the N-oxide group is a hydrogen-bond acceptor.•X-ray, IR, Raman and DFT methods recognized the existence of the intramolecular N–H⋯O hydrogen bond in the studied compound.
•Basing on the DFT QCC the structures of these compounds have been proposed.•The IR and RS wavenumbers were calculated for monomers and dimers.•IR, RS and DFT methods confirm the existence of an ...intra- and an inter-molecular HBs.•The vibrational characteristics of the hydrazo-bond have been reported.•The influence of substitution position of the methyl group on the vibrational data.
Syntheses of 5-nitro-2-(2-phenylhydrazinyl)pyridine (5-nitro-2-phenylhydrazopyridine), 3-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (3-methyl-5-nitro-2-phenylhydrazopyridine), 4-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (4-methyl-5-nitro-2-phenylhydrazopyridine) and 6-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (6-methyl-5-nitro-2-phenylhydrazopyridine) have been described. Their IR and Raman spectra have been measured and analyzed in terms of DFT quantum chemical calculations. The 6-311G(2d,2p) basis set with the B3LYP functional has been used to discuss the optimized structure and vibrational spectra. The vibrational characteristics of the hydrazo-bond have been reported with their relation to the inter- and intra-molecular hydrogen bonds formed in the studied systems. The role and influence of substitution position of the methyl chromophore on the structure and vibrational data have been discussed.
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► The crystal structure of 6-methyl-3-nitro-2-(2-phenylhydrazinyl)pyridine was studied. ► The IR and Raman wavenumbers have been calculated from the optimized geometry of monomer and ...dimer. ► X-ray, IR, Raman and DFT methods confirm the existence of an intramolecular NH···O bond.
The crystal and molecular structures of 6-methyl-3-nitro-2-(2-phenylhydrazinyl)pyridine (6-methyl-3-nitro-2-phenylhydrazopyridine) have been determined by X-ray diffraction and quantum chemical DFT analysis. The crystal is monoclinic, space group C2/c, with Z=8 formula units in the elementary unit cell of dimensions a=16.791(4), b=6.635(2), c=21.704(7)Å, β=100.54(3)°. The molecule consists of two nearly planar pyridine subunits. A conformation of the linking hydrazo-bridge CNHNHC is bend and the dihedral angle between the planes of the phenyl and pyridine rings is 88.2(5)°. The hydrogen bonding of the type NH···N and possibly also CH···O favors a dimer formation in the crystal structure. The dimers are further linked by a NH···O hydrogen bond, so forming a layer parallel to the ab plane. The molecular structure of the studied compound has been determined using the DFT B3LYP/6-311G(2d,2p) approach and compared to that derived from X-ray studies. The IR and Raman wavenumbers have been calculated for the optimized geometry of a possible monomer structural model but the possibility of the dimer formation through the NH···N hydrogen bond has also been considered. The structural and vibrational properties of the intra-molecular NH···O interaction are described.
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► The crystal structures of 3- and 5-nitroderivatives of 2-amino-4-methylpyridine were studied. ► These structures exhibit layered arrangement with a dimeric N–H···N motif. ► The IR ...and Raman wavenumbers have been calculated from the optimized geometry of monomers and dimers. ► X-ray, IR, Raman and DFT methods confirm the existence of intermolecular N–H···N bonds.
The crystal structures of 2-amino-4-methyl-3-nitropyridine (I), 2-amino-4-methyl-3,5-dinitropyridine (II) and 2-amino-4-methyl-5-nitropyridine (III) have been determined. The compounds crystallize in the monoclinic P21/n, triclinic P-1 and monoclinic C2/c space groups, respectively. These structures are stabilized by a combination of N–H···N and N–H···O hydrogen bonds and exhibit layered arrangement with a dimeric N–H···N motif in which the molecular units are related by inversion centre. The molecular structures of the studied compounds have been determined using the DFT B3LYP/6-311G(2d,2p) approach and compared to those derived from X-ray studies. The IR and Raman wavenumbers have been calculated from the optimized geometry of monomers and dimers formed in the unit cell and compared to the experimental values obtained from the spectra.
Syntheses of 5-nitro-2-(2-phenylhydrazinyl)pyridine (5-nitro-2-phenylhydrazopyridine), 3-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (3-methyl-5-nitro-2-phenylhydrazopyridine), ...4-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (4-methyl-5-nitro-2-phenylhydrazopyridine) and 6-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (6-methyl-5-nitro-2-phenylhydrazo-pyridine) have been described. Electronic absorption and emission spectra of the compounds in the solid state and in various solvents have been measured at room temperature and discussed in terms of DFT quantum chemical calculations. The molecular structures and energy sequences of the singlet and triplet states have been determined in the B3LYP/6-311G(2d,2p) approximations. The Mulliken analysis and non-bonding orbital approach have been used in characterization of the studied compounds. It has been shown that the HOMO-LUMO transition of the studied compounds is observed in the range 23,900 ÷ 29,300 cm−1 and in this excitation the π-electrons of phenyl ring are transferred to nitro group of pyridine ring. In such a transition the hydrazo-bridge should take part as a mediator. The luminescence of the studied hydrazo-compounds is weak, not measureable in the solid state but measureable in solution.
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•5-nitro-2-phenylhydrazopyridine and its three methyl isomers were synthesized.•The UV–Vis spectra in the solid state and in various solvents were measured.•Their electronic spectra were discussed in terms of quantum chemical calculations.
•Two new organic–organic salts, AMNP-TFA and AMNP-HBS, were obtained and characterized.•NH⋯O bonds are formed between the acidic unit and pyridinium cation in both salts.•OH⋯O bonds are formed ...between H2O molecules and COO− and NO2 groups in AMNP-TFA.•The SO3- groups of adjacent acidic unit are linked by OH···O bonds in AMNP-HBS.•X-ray, IR and Raman studies and DFT calculations show the existence of intramolecular NH···O bonds.
Two new organic–organic salts, 2-amino-4-methyl-5-nitropyridinium trifluoroacetate monohydrate (AMNP-TFA), and 2-amino-4-methyl-5-nitropyridinium 4-hydroxybenzenesulfonate (AMNP-HBS), were obtained and characterized by means of FT-IR, FT-Raman and single crystal X-ray crystallography. In the former crystal, the cations, anions and water molecules are linked into layers by three types of hydrogen bonds, NPH⋯O, NAH⋯O and OH⋯O. These layers are connected by weaker CH⋯O hydrogen bonds. In the latter crystal, the cations and anions form one-dimensional structure through a number of hydrogen-bonding interactions involving the OH, NH+ and NH2 groups as donors. In this case the NPH⋯O and NAH⋯O hydrogen bonds are formed. The combination of interactions between cations and anions results in the formation of columns. Additionally, there are π–π stacking interactions between the columns. The obtained X-ray structural data are related to the vibrational spectra of the studied crystals.
Fourier transform polarized IR and Raman spectra of bis(guanidine) zirconium bis(nitrilotriacetate) hydrate single crystal C(NH
2)
3
2{ZrN(CH
2COO)
3
2}(H
2O) have been measured in the regions ...30–4000 and 80–4000
cm
−1 and correlated with X-ray structural data. The factor group analysis has been applied in the discussion of the dichroic dependence of the vibrational modes. The assignment of the internal vibrations for the {Zr(nitrilotriacetate)
2}
2− complex ion has been based on the ab initio quantum chemical calculations. The usefulness of the studied crystal as Raman laser converter was analyzed basing on the comparison of the spontaneous and stimulated Raman spectra.
The paper presents the molecular and XRD structures as well as room temperature IR and Raman studies of 2-hydroxy-3-cyano-4-methylpyridine. The nature and assignment of the vibrational modes have ...been discussed on the basis of the quantum chemical calculations performed with the use of B3LYP/6-311G(d,p) basis set. The role of the hydrogen bonds in the stabilization of the structure has been analyzed. The quantum chemical calculations have been performed for the monomer as well as for the dimer coupled via the hydrogen bonds. A possible application of this compound in the hybrid formation technology is discussed.
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