| 1. |
- Gyepesova, Dalma, et al.
(author)
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Structural aspects of some Cu(II) complexes containing Schiff base.
- 2004
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In: Abstracts, ECM-22, 26-31 August 2004, Budapest, Hungary, Acta Cryst.. - 9639319406 ; A60, s. 266-
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Conference paper (other academic/artistic)abstract
- A group of copper(II) complexes containing Schiff bases,derived from salicylaldehyde and various amino acids, isinteresting due to their biological activities. Structures of (N-salicylidene-rac-glutamato)(1-methylimidazole)Cu(II) I, (Nsalicylidene-rac-glutamato)(2-methylimidazole)Cu(II) II and (N-salicylidene-L-glutamato)(2-ethylimidazole)Cu(II)III have been determined. Electron structure of thesecompounds has been investigated by the B3LYP method.In the all here presented complexes three donor atoms (O, Nand O) of the Schiff base and a fourth donor atom from theimidazole ligand (N) define the basal plane of Cu(II).Depending on different substituents R1 and R2 on theimidazole ring, changes of coordination sphere of Cu(II) isvarying (square-planar or square-pyramidal) as well as way of packing of molecules in the crystal.
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| 2. |
- Langer, Vratislav, 1949, et al.
(author)
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(1-Methylimidazole)(N-salicylidene-rac-glutamato)copper(II)
- 2003
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In: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; E59:12, s. m1181-m1183
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Journal article (peer-reviewed)abstract
- The title racemic compound, [Cu(C12H11NO5)(C4H6N2)], adopts a square-planar copper(II) coordination mode with the tridentate N-salicylidenglutamato Schiff base dianion and the 1-methylimidazole ligand. Dimers of centrosymmetrically related molecules are formed. The theoretical investigation of the electronic structure of the title compound by the B3LYP method is presented.
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| 3. |
- Langer, Vratislav, 1949, et al.
(author)
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2-(2-Oxazolin-2-yl)benzene-1,4-diol: X-ray and density functional theory studies
- 2007
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In: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; 63:3, s. o187-o189
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Journal article (peer-reviewed)abstract
- In the crystal structure of the title compound, C9H9NO3, there are strong intramolecular O-H...N and intermolecular O-H...O hydrogen bonds which, together with weak intermolecular C-H...O hydrogen bonds, lead to the formation of infinite chains of molecules. The calculated intermolecular hydrogen-bond energies are -11.3 and -2.7 kJ mol-1, respectively, showing the dominant role of the O-H...O hydrogen bonding. A natural bond orbital analysis revealed the electron contribution of the lone pairs of the oxazoline N and O atoms, and of the two hydroxy O atoms, to the order of the relevant bonds.
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| 4. |
- Langer, Vratislav, 1949, et al.
(author)
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2-(4-Hydroxyphenyl)-4,4-dimethyl-2-oxazoline: X-ray and density functional theory study
- 2006
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In: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; C62:7, s. o416-o418
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Journal article (peer-reviewed)abstract
- In the crystal structure of the title compound, C11H13NO2, there are strong intermolecular O-H...N hydrogen bonds which, together with weak intramolecular C-H...O hydrogen bonds, lead to the formation of infinite chains of molecules, held together by weak intermolecular C-H...O hydrogen bonds. A theoretical investigation of the hydrogen bonding, based on density functional theory (DFT) employing periodic boundary conditions, is in agreement with the experimental data. The cluster approach shows that the influence of the crystal field and of hydrogen-bond formation are responsible for the deformation of the 2-oxazoline ring, which is not planar and adopts a 4T3 (C3TC2) conformation.
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| 5. |
- Langer, Vratislav, 1949, et al.
(author)
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2-Anilinomethylene-3-oxobutanenitrile: an X-ray and density functional theory study
- 2006
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In: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; C62:9, s. o554-o546
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Journal article (peer-reviewed)abstract
- Molecules of the title compound, C11H10N2O, are effectively planar. In the crystal structure, they are stabilized primarily by electrostatic interactions, as the dipole moment of the molecule is 4.56 D. In addition, the molecules are linked by weak C-H...N and C-H...O hydrogen bonds. An analysis of bonding conditions in the molecule was carried out using natural bond orbital (NBO) formalism.
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| 6. |
- Langer, Vratislav, 1949, et al.
(author)
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3-(4-Bromophenyl)-5-(4-dimethylaminophenyl)-1-phenyl-2-pyrazoline: X-ray and density functional theory (DFT) studies
- 2007
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In: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; C63:6, s. o340-o342
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Journal article (peer-reviewed)abstract
- In the crystal structure of the title compound, C23H22BrN3, a strong conjugation of the pyrazoline chromophore with the aromatic rings at positions 1 and 3 is observed, as well as a significant shift in the synclinal→synperiplanar direction. The absolute structure was unequivocally determined. In the absence of clasical hydrogen-bond donors, the structure is stabilized by weak C-H…π interactions. This paper also reports the electronic structure of the title compound using NBO (natural bond order) analysis. The contributions of lone pairs to the relevant bonds were revealed.
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| 7. |
- Langer, Vratislav, 1949, et al.
(author)
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anti-2-Hydroxy-2-methyl-1-tetralone oxime: X-ray and density functional theory study
- 2006
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In: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; C62:4, s. o199-o202
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Journal article (peer-reviewed)abstract
- Crystals of the title racemic compound, C11H13NO2, consist of two types of molecules (conformers); one molecule has an exocyclic OH group in an equatorial position and the other has this group in an axial position. Consequently, the hydrogen-bond schemes for the two molecules are different. The molecules with equatorial OH groups create infinite parallel chains (formed by the same enantiomer), connected by centrosymmetric dimers of molecules (of mixed enantiomers), both with axial OH groups. Possible interconversion of the conformers and the flexibility of the molecule were studied by means of different MP2 and density functional theory (DFT) methods. The optimization of the structure by the DFT method confirmed the types of the hydrogen bonds.
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| 8. |
- Langer, Vratislav, 1949, et al.
(author)
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Crystal and electronic structure of aqua(N-salicylidene-methylester-L-glutamato)Cu(II) monohydrate
- 2004
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In: Zeitschfrift für Kristallographie. - : Walter de Gruyter GmbH. - 0044-2968. ; 219:2, s. 112-116
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Journal article (peer-reviewed)abstract
- The absolute structure of the title compound, CuNC13H17O7, has been determined. The crystal structure consists of the molecular units Cu(N-sal-5-met-L-glu)(H2O) connected by a three-dimensional network of hydrogen bonds. The coordination polyhedron in the complex is approximately square-pyramidal with a pentacoordinated Cu(II) atom. The base of the pyramid is formed by nitrogen and oxygen atoms belonging to the molecule, while the apex of the pyramid contains a weakly bonded oxygen atom of the carboxylic group of another molecule. The B3LYP/SVP method and basis set in Gaussian98 was used for quantum chemical calculation of the nature of CuX (X = O, N) bonds. While the calculated dissociation energy of the weakly bonded crystalline water is only 17.2 kJ/mol, the bonding energy of the water molecule coordinating to the Cu atom is 62.3 kJ/mol.
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| 9. |
- Langer, Vratislav, 1949, et al.
(author)
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(E)-Methyl 2-anilinomethylene-3-oxobutanoate: X-ray and density functional theory studies
- 2007
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In: Acta Crystallographica Section C: Crystal Structure Communications. - 0108-2701 .- 1600-5759. ; C63:9, s. o552-o554
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Journal article (peer-reviewed)abstract
- Molecules of the title compound, C12H13NO3, are not planar and are stabilized by electrostatic interactions, as the dipole moment of the molecule is 3.76 D. They are also stabilized by intramolecular hydrogen bonds of N...O and C...O types, and by a complicated network of weak intermolecular hydrogen bonds of the C...O type. This paper also reports the theoretical investigation of the hydrogen bonding and electronic structure of the title compound using natural bond orbital (NBO) analysis.
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| 10. |
- Langer, Vratislav, 1949, et al.
(author)
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(N-salicylidene-D,L-glutamato) (2-methylimidazole)copper(II).
- 2004
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In: Acta Crystallographica Section E: Structure Reports Online. - 1600-5368. ; E60:1, s. m129-m132
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Journal article (peer-reviewed)abstract
- The title racemic compound, [Cu(C12H11NO5)(C4H6N2)], adopts a square-pyramidal Cu(II) coordination with the tridentate N-salicylideneglutamate Schiff base dianion and the 2-methylimidazole ligand in the basal plane. The apex of the pyramid is occupied by a carboxylic acid O atom from the neighbouring chelate at a distance of 2.479(4)Å, leading to infinite one-dimensional chains along the crystallographic a axis. Strong N-H...O and O-H...O hydrogen bonds form a helix parallel to the c axis. The electronic structure of the title compound has also been investigated by the B3LYP method.
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| 11. |
- Scholtzová, Eva, et al.
(author)
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Crystal Structure, Infrared Spectra and DFT Study of Benzyl 2,3-Anhydro-β-D-Ribopyranoside
- 2011
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In: Journal of Chemical Crystallography. - 1074-1542 .- 1572-8854. ; 41:2, s. 167-174
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Journal article (peer-reviewed)abstract
- The crystal structure of benzyl 2,3-anhydro-β-D-ribopyranoside is orthorhombic, P212121, Z = 4. The pyranose ring adopts the EO conformation distorted considerably to the 5HO direction. The molecules of the title compound are linked into infinite chains running along the a-axis by bifurcated O–H···O hydrogen bonds. Interaction energies of these hydrogen bonds are significantly different, ~−5.4 for the bond with the smaller and ~−1.1 kcal/mol for the bond with the larger O···O separation. The hydrogen-bond pattern is completed by the two weaker C–H···O intermolecular hydrogen bonds, aiming at the epoxy oxygen atom. IR vibrational spectrum was interpreted by means of comparison with the full list of vibrational modes predicted using DFT method in the solid state. While till 1495 cm−1 the individual bands can be reconciled with single calculated modes, the region below this limit is populated by heavily overlapped HCH, HCO, HOC, COC and HCC bending modes merged with few ν(CC) and ν(CO) modes. The respective “red” shifts of the positions of the ν(OH) bands correlate well with the size of the O···O separation.
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