scholarly journals Synthesis and Conformational Analysis of Sterically Congested (4R)-(−)-1-(2,4,6-Trimethylbenzenesulfonyl)-3-n-butyryl-4-tert-butyl-2-imidazolidinone: X-Ray Crystallography and Semiempirical Calculations

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Ibrahim A. Al-Swaidan ◽  
Adel S. El-Azab ◽  
Amer M. Alanazi ◽  
Alaa A.-M. Abdel-Aziz
Keyword(s):  
Crystal Structure ◽  
Conformational Analysis ◽  
Phenyl Ring ◽  
Crystal Packing ◽  
Molecular Mechanic ◽  
Structural Data ◽  
Am1 Method ◽  
Geometrical Parameters ◽  
X Ray ◽  
X Ray Crystallography

The crystal structure of (4R)-(−)-1-(2,4,6-trimethylbenzenesulfonyl)-3-n-butyryl-4-tert-butyl-2-imidazolidinone(3)was determined by single-crystal X-ray diffraction. Compound3crystallizes in triclinic system in space groupP1 (≠1). The crystal data area=10.62165 Å,b=16.5321 Å,c=8.95729 Å,∝=91.1936∘,β=93.8496∘,γ=88.0974∘,V=1568.22 Å3,Z=3,Dcalc=1.253 g/cm3,μCuKα=15.98 cm−1,F000=636.00,T=20.0°C, andR=0.037. The crystal structure confirmed the occurrence of three molecules of3A,3B, and3Cin which then-butyryl moiety adopted thes-transoidconformation. Crystal structure also revealed that the conformation of 2,4,6-trimethylbenzenesulfonyl groups was inanti-position relative totert-butyl group. The crystal packing showed that three molecules of compound3are stacked as a result of intermolecularπ-πinteractions between the phenyl ring of one molecule and the phenyl ring of the other molecule by approaching each other to an interplanar separation of 5.034 Å. Interestingly, these stacked molecules are also connected by intermolecularCH-πinteraction. The conformational analysis of thes-transoid  3A,3B, and3Cwas separately performed by molecular mechanic MM+ force field. Additionally, computational investigation using semiempirical AM1 and PM3 methods was performed to find a correlation between experimental and calculated geometrical parameters. The data obtained suggest that the structural data furnished by the AM1 method is in better agreement with those experimentally determined for the above compound. It has been found that the lowest energetic conformer computed gives approximate correspondence with experimental solid state data.

Structural studies of some 1-polymethyleneimino-2,4-dinitrobenzenesand related compounds; crystal structure of 1-(cis-2′,6′-dimethylpiperidin-1′-yl)-2,4-dinitrobenzene

2000 ◽  
Vol 53 (8) ◽  
pp. 715 ◽  
Author(s):  
Maureen F. Mackay ◽  
Douglas J. Gale ◽  
John F. K. Wilshire
Keyword(s):  
Crystal Structure ◽  
Phenyl Ring ◽  
Ring Opening ◽  
Boat Conformation ◽  
Structural Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Mean ◽  
Related Compounds ◽  
Solid State Conformation

The ultraviolet and 1H n.m.r. spectra of some 1-polymethyleneimino-2,4-dinitrobenzenes and related compounds are discussed. The effect of trifluoroacetic acid on these spectra was also investigated; with 1-azetidinyl-2,4-dinitrobenzene, acid-catalysed ring opening was observed. The solid-state conformation of 1-(cis-2′,6′-dimethylpiperidin-1′-yl)-2,4-dinitrobenzene has been defined by single-crystal X-ray crystallography. Triclinic crystals belong to the space group P–1 with a 8.165(1), b 7.865(1), c 11.148(1) Å, α 95.23(1), β 106.00(1), γ 92.63(1)˚ and Z 2. The structure was refined to a final R of 0.048 for the 2222 observed data. In the crystal, the phenyl ring adopts a slight boat conformation, while the amino and o-nitro groups are significantly twisted from the mean plane of the ring.

scholarly journals Synthesis, Characterization, and Bioactivity of Schiff Bases and TheirCd2+,Zn2+,Cu2+, andNi2+Complexes Derived from Chloroacetophenone Isomers with S-Benzyldithiocarbazate and the X-Ray Crystal Structure of S-Benzyl-β-N-(4-chlorophenyl)methylenedithiocarbazate

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Mohammed Khaled bin Break ◽  
M. Ibrahim M. Tahir ◽  
Karen A. Crouse ◽  
Teng-Jin Khoo
Keyword(s):  
Crystal Structure ◽  
Phenyl Ring ◽  
Crystallographic Analysis ◽  
Gram Negative Bacteria ◽  
Schiff Base Ligands ◽  
Gram Negative ◽  
X Ray ◽  
X Ray Crystallography ◽  
Gram Positive Bacteria ◽  
Antimicrobial Assay

Two bidentate Schiff base ligands having nitrogen sulphur donor sequence were derived from the condensation of S-benzyldithiocarbazate (SBDTC) with 2-chloroacetophenone and 4-chloroacetophenone to give S-benzyl-β-N-(2-chlorophenyl)methylenedithiocarbazate (NS2) and S-benzyl-β-N-(4-chlorophenyl)methylenedithiocarbazate (NS4) isomers. Each of the ligands was then chelated with Cd2+, Zn2+, Cu2+, and Ni2+. The compounds were characterized via IR spectroscopy and melting point while the structure of NS4 was revealed via X-ray crystallography. Finally, the compounds were screened for antimicrobial activity to investigate the effect that is brought by the introduction of the chlorine atom to the benzene ring. X-ray crystallographic analysis showed that the structure of NS4 is planar with a phenyl ring that is nearly perpendicular to the rest of the molecules. The qualitative antimicrobial assay results showed that NS4 and its complexes lacked antifungal activity while Gram-positive bacteria were generally inhibited more strongly than Gram-negative bacteria. Furthermore, NS4 metal complexes were inhibited more strongly than the ligand while the opposite was seen with NS2 ligand and its complexes due to the partial solubility in dimethyl sulfoxide (DMSO). It was concluded that generally NS2 derivatives have higher bioactivity than that of NS4 derivatives and that the Cd complexes of both ligands have pronounced activity specifically onK. rhizophila.

scholarly journals Molecular and crystal structure, optical properties and DFT studies of 1,4-dimethoxy-2,5-bis[2-(4-nitrophenyl)ethenyl]benzene

2020 ◽  
Vol 76 (6) ◽  
pp. 940-943
Author(s):  
Georgii Bogdanov ◽  
Evgenii Oskolkov ◽  
Jenna Bustos ◽  
Viktor Glebov ◽  
John P. Tillotson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phenyl Ring ◽  
Crystal Packing ◽  
Dft Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vertical Excitation ◽  
Benzene Rings ◽  
Homo And Lumo ◽  
Title Molecule

The title compound DBNB, C24H20N2O6, has been crystallized and studied by X-ray diffraction, spectroscopic and computational methods. In the title molecule, which is based on a 1,4-distyryl-2,5-dimethoxybenzene core with p-nitro-substituted terminal benzene rings, the dihedral angle between mean planes of the central fragment and the terminal phenyl ring is 16.46 (6)°. The crystal packing is stabilized by π–π interactions. DFT calculations at the B3LYP/6–311 G(d,p) level of theory were used to compare the optimized structures with the experimental data. Energy parameters, including HOMO and LUMO energies, their difference, and vertical excitation and emission energies were obtained.

scholarly journals First structure of full-length mammalian phenylalanine hydroxylase reveals the architecture of an autoinhibited tetramer

2016 ◽  
Vol 113 (9) ◽  
pp. 2394-2399 ◽  
Author(s):  
Emilia C. Arturo ◽  
Kushol Gupta ◽  
Annie Héroux ◽  
Linda Stith ◽  
Penelope J. Cross ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phenylalanine Hydroxylase ◽  
Allosteric Regulation ◽  
Structural Data ◽  
Homology Model ◽  
Full Length ◽  
X Ray ◽  
X Ray Crystallography ◽  
Domain Motions ◽  
And Function

Improved understanding of the relationship among structure, dynamics, and function for the enzyme phenylalanine hydroxylase (PAH) can lead to needed new therapies for phenylketonuria, the most common inborn error of amino acid metabolism. PAH is a multidomain homo-multimeric protein whose conformation and multimerization properties respond to allosteric activation by the substrate phenylalanine (Phe); the allosteric regulation is necessary to maintain Phe below neurotoxic levels. A recently introduced model for allosteric regulation of PAH involves major domain motions and architecturally distinct PAH tetramers [Jaffe EK, Stith L, Lawrence SH, Andrake M, Dunbrack RL, Jr (2013) Arch Biochem Biophys 530(2):73–82]. Herein, we present, to our knowledge, the first X-ray crystal structure for a full-length mammalian (rat) PAH in an autoinhibited conformation. Chromatographic isolation of a monodisperse tetrameric PAH, in the absence of Phe, facilitated determination of the 2.9 Å crystal structure. The structure of full-length PAH supersedes a composite homology model that had been used extensively to rationalize phenylketonuria genotype–phenotype relationships. Small-angle X-ray scattering (SAXS) confirms that this tetramer, which dominates in the absence of Phe, is different from a Phe-stabilized allosterically activated PAH tetramer. The lack of structural detail for activated PAH remains a barrier to complete understanding of phenylketonuria genotype–phenotype relationships. Nevertheless, the use of SAXS and X-ray crystallography together to inspect PAH structure provides, to our knowledge, the first complete view of the enzyme in a tetrameric form that was not possible with prior partial crystal structures, and facilitates interpretation of a wealth of biochemical and structural data that was hitherto impossible to evaluate.

Kinetic benzylidenation. Part I. The selective formation of five-membered ring benzylidene acetals from aldose diethyl dithioacetals

1986 ◽  
Vol 64 (12) ◽  
pp. 2388-2396 ◽  
Author(s):  
T. Bruce Grindley ◽  
Srihari Kusuma ◽  
T. Stanley Cameron
Keyword(s):  
Crystal Structure ◽  
Phenyl Ring ◽  
Dimethyl Acetal ◽  
Membered Ring ◽  
Sugar Chain ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cell Dimensions ◽  
Intermolecular Reaction ◽  
Selective Formation

Reaction of D-arabinose diethyl dithioacetal with one equivalent of benzaldehyde dimethyl acetal in the presence of p-toluenesulfonic acid at −40 °C gave a mixture of the two epimers of 5-O-methoxyphenylmethyl-D-arabinose diethyl dithioacetal initially. After 14 h at −20 °C, the major products were R- and S-4,5-O-benzylidene-D-arabinose diethyl dithioacetal. The structure of the S isomer was determined by X-ray crystallography. The crystal was orthorhombic, with space group P212121, cell dimensions a = 5.179(4), b = 12.469(3), c = 27.150(4) Å, and Z = 4. The crystal structure was solved using the SHELX (76) system and refined to R = 0.060 for 714 reflections. The sugar chain was in a zigzag conformation, the 4,5-O-benzylidene ring in a 0−5Tc conformation, and the plane of the phenyl ring was nearly perpendicular to the plane of the five-membered ring (88° angle). There were two short OH—S hydrogen bonds, one intramolecular and one intermolecular. Reaction of the diethyl dithioacetals of D-glucose, D-galactose, D-mannose, and D-ribose at −20 °C as above also gave mixtures of the terminal five-membered ring O-benzylidene diastereomers.

scholarly journals Fine-tuning of biaryl dihedral angles: structural characterization of five homologous three-atom bridged biphenyls by X-ray crystallography

2005 ◽  
Vol 61 (3) ◽  
pp. 335-345 ◽  
Author(s):  
David J. Edwards ◽  
Robin G. Pritchard ◽  
Timothy W. Wallace
Keyword(s):  
Crystal Structure ◽  
Crystal Packing ◽  
Crystal Structure Analysis ◽  
Fine Tuning ◽  
Dihedral Angles ◽  
X Ray ◽  
X Ray Crystallography ◽  
Potential Control ◽  
Derivatives Of

The homologous series of three-atom bridged biaryls comprising 5,7-dihydro-1,2,3,9,10,11-hexamethoxydibenzo[c,e]oxepine, 6,7-dihydro-1,2,3,9,10,11-hexamethoxy-6-methyl-5H-dibenzo[c,e]azepinium chloride, 5,7-dihydro-1,2,3,9,10,11-hexamethoxydibenzo[c,e]thiepine, and the 6-oxide and 6,6-dioxide derivatives of the latter have been characterized by X-ray crystal structure analysis. Within this series the endocyclic and exocyclic biaryl dihedral angles vary over 10° ranges, reflecting the changing balance of intramolecular (steric, geometric) and intermolecular (crystal packing) forces, the former being potential control elements for fine-tuning the helicity of the biaryl system.

Verfeinerung der Kristallstruktur von Tripalladium-di-tetrathiophospliat Pd3(PS4)2 Refinement of the Crystal Structure of Tripalladium-di-tetrathiophosphate Pda3(PS4)2

1983 ◽  
Vol 38 (4) ◽  
pp. 426-427 ◽  
Author(s):  
Arndt Simon ◽  
Karl Peters ◽  
Harry Hahn
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Title Compound ◽  
Type Structure ◽  
Tetrahedral Symmetry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Planar Environment

Abstract The structure of the title compound has been determined by X-ray crystallography. The title compound is synthesized from the elements at 600 °C. Its crystal structure, derived from powder data [3] is refined by single crystal diffractometer data. The structure is trigonal (P3̅ml, α = 684.1(1), c = 724.4(1) pm); Pd2+ cations and PS43- anions form a network with an anti-Claudetite (AS2O3) type structure. The PS4 units are distinctly distorted from ideal tetrahedral symmetry. The Pd atoms have a planar environment of 4 S atoms.

Model of the Second Most Abundant Cisplatin−DNA Cross-Link:  X-ray Crystal Structure and Conformational Analysis ofcis-[(NH3)2Pt(9-MeA-N7)(9-EtGH-N7)](NO3)·2H2O (9-MeA = 9-Methyladenine; 9-EtGH = 9-Ethylguanine)

1996 ◽  
Vol 35 (6) ◽  
pp. 1647-1652 ◽  
Author(s):  
Guy Schröder ◽  
Jirí Kozelka ◽  
Michal Sabat ◽  
Marie-Hélène Fouchet ◽  
Rut Beyerle-Pfnür ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Conformational Analysis ◽  
Cross Link ◽  
X Ray
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