scholarly journals Molecular symmetry

2021 ◽  
Author(s):  
Ajit J Thakkar
Keyword(s):  
Molecular Symmetry

The molecular symmetry of bovine liver catalase

1975 ◽  
Vol 93 (1) ◽  
pp. 55-62 ◽  
Author(s):  
William Eventoff ◽  
G.V. Gurskaya
Keyword(s):  
Bovine Liver ◽  
Molecular Symmetry ◽  
Bovine Liver Catalase

Studies in aryltin chemistry. Part 6. Crystal and molecular structures of tetra(p-methylsulphonylphenyl)tin(IV) and tetra(p-methylsulphinylphenyl)tin(IV) monohydrate

1990 ◽  
Vol 68 (8) ◽  
pp. 1277-1282 ◽  
Author(s):  
Ivor Wharf ◽  
Michel G. Simard ◽  
Henry Lamparski
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
Direct Method ◽  
Molecular Structures ◽  
Water Molecules ◽  
Monoclinic Space Group ◽  
Molecular Symmetry ◽  
Asymmetric Unit ◽  
Full Matrix ◽  
Space Group

Tetrakis(p-methylsulphonylphenyl)tin(IV) and tetrakis(p-methylsulphinylphenyl)tin(IV) n-hydrate have been prepared and their spectra (ir 1350–400 cm−1; nmr, 1H, 13C, 119Sn) and X-ray crystal structures are reported. The first compound is monoclinic, space group C2/c, Z = 4, with a = 21.589(6), b = 6.207(3), c = 22.861(11) Å, β = 93.80(3)° (22 °C); the structure was solved by the direct method and refined by full-matrix least squares calculations to R = 0.043 for 2755 observed reflections. It has 2 molecular symmetry with the methyl group and one oxygen atom completely disordered in both CH3S(O2) groups in the asymmetric unit. The second compound is tetragonal, space group P42/n, Z = 2, with a = b = 15.408(6), c = 6.379(2) Å (−100 °C); the structure was solved by the Patterson method and refined by full-matrix least squares calculations to R = 0.060 for 1209 observed reflections. It has [Formula: see text] molecular symmetry with the whole asymmetric unit disordered. Water molecules occupy positions on parallel 42 axes but molecular packing requirements prevent all sites having 100% occupancy giving n ~ 1 for the hydrate. Keywords: Tetra-aryltins, crystal structures, sulphone, sulphoxide, hydrogen-bonding.

Teaching Molecular Symmetry of Dihedral Point Groups by Drawing Useful 2D Projections

2015 ◽  
Vol 92 (8) ◽  
pp. 1422-1425 ◽  
Author(s):  
Lan Chen ◽  
Hongwei Sun ◽  
Chengming Lai
Keyword(s):  
Molecular Symmetry ◽  
Point Groups

Surface-Enhanced Resonance Raman Spectra Study of α,β,γ,δ-Tetra-(4-Trimethyl Ammonium Phenyl) Porphyrin

1993 ◽  
Vol 47 (3) ◽  
pp. 292-295 ◽  
Author(s):  
Jian Chen ◽  
Ji-Ming Hu ◽  
Zhi-San Xu ◽  
Rong-Sheng Sheng
Keyword(s):  
Group Theory ◽  
Phenyl Ring ◽  
Resonance Raman ◽  
Vibrational Modes ◽  
Molecular Symmetry ◽  
Resonance Raman Scattering ◽  
Porphyrin Macrocycle ◽  
Surface Enhanced ◽  
Ag Colloid ◽  
Resonance Raman Spectra

In the present study, surface-enhanced resonance Raman scattering (SERRS) spectra of α,β,γ,δ-tetra-(4-trimethyl ammonium phenyl) porphyrin [T(4-TAP)P] were obtained. With increasing pH, the relative intensities of the bands at 890 and 1244 cm−1 decreased. These bands were attributed to γ(C-H) and δ(Cm-phenyl), respectively. The bands at 420 and 576 cm−1, which were assigned to γ(phenyl-ring), were enhanced. The molecular symmetry of T(4-TAP)P is discussed in terms of group theory. The bands at 1554 and 1496 cm−1 could be attributed to the vibrational modes of the porphyrin macrocycle; the bands at 1460, 1362, and 1330 cm−1 were assigned to ν(C-C) + δ(C-H), ν(C-N) + δ(C-H), and ν(C-N), respectively. All these bands change in band intensities, positions and widths, with the potential changing from +0.2 V to −0.2 V. It was concluded that the adsorbed porphyrins underwent partial incorporation with Ag from the electrode, and the adsorbate assumed a flat orientation on the silver electrode as well as the Ag colloid surface.

scholarly journals Crystal structure oftrans-N,N′-bis(3,5-di-tert-butyl-2-hydroxyphenyl)oxamide methanol monosolvate

2016 ◽  
Vol 72 (7) ◽  
pp. 918-921
Author(s):  
Miguel-Ángel Velázquez-Carmona ◽  
Sylvain Bernès ◽  
Francisco Javier Ríos-Merino ◽  
Yasmi Reyes Ortega
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Hydroxy Group ◽  
Molecular Conformation ◽  
Methanol Molecule ◽  
Molecular Symmetry ◽  
Methyl Group ◽  
Supramolecular Motifs ◽  
Butyl Group ◽  
Hydroxy Groups

The here crystallized oxamide was previously characterized as an unsolvated species [Jímenez-Pérezet al.(2000).J. Organomet. Chem.614–615, 283–293], and is now reported with methanol as a solvent of crystallization, C30H44N2O4·CH3OH, in a different space group. The introduction of the solvent influences neither the molecular symmetry of the oxamide, which remains centrosymmetric, nor the molecular conformation. However, the unsolvated molecule crystallized as an ordered system, while many parts of the solvated crystal are disordered. The hydroxy group in the oxamide is disordered over two chemically equivalent positions, with occupancies 0.696 (4):0.304 (4); onetert-butyl group is disordered by rotation about the C—C bond, and was modelled with three sites for each methyl group, each one with occupancy 1/3. Finally, the methanol solvent, which lies on a twofold axis, is disordered by symmetry. The disorder affecting hydroxy groups and the solvent of crystallization allows the formation of numerous supramolecular motifs using four hydrogen bonds, with N—H and O—H groups as donors and the oxamide and methanol molecule as acceptors.

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