Conglomerate crystallization in organic compounds. Part 3. the X-ray diffraction crystal structure of triphenyl methane, molecular mechanics, and quantum mechanical calculations of the structure and energetics of this molecular propeller

1997 ◽  
Vol 8 (4) ◽  
pp. 263-273 ◽  
Author(s):  
D. C. Levendis ◽  
I. Bernal
Keyword(s):  
Crystal Structure ◽  
Molecular Mechanics ◽  
Organic Compounds ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Conglomerate Crystallization

Crystal Forms of Semisynthetic Ergot Alkaloid Terguride

2002 ◽  
Vol 67 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Ladislav Cvak ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ergot Alkaloid ◽  
Simplified Model ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystal Forms ◽  
X Ray ◽  
Independent Molecules

Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.

Crystal Structure and Tautomerism of 1-[N-(4-Iodophenyl)]aminomethylidene-2(1H)naphthalenone

2001 ◽  
Vol 56 (10) ◽  
pp. 1003-1008 ◽  
Author(s):  
H. Ünver ◽  
M. Kabak ◽  
D. M. Zengin ◽  
T. N. Durlu
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Quantum Mechanical ◽  
Monoclinic Space Group ◽  
Quantum Mechanical Calculations ◽  
X Ray ◽  
H Nmr ◽  
Mechanical Methods ◽  
Intramolecular Hydrogen ◽  
Semi Empirical

1-[N-(4-Iodophenyl)]aminomethylidene-2(1H)naphthalenone (1) (C17H12NOI) has been studied by X-ray analysis, IR, 1H NMR, UV and AM1 semi-empirical quantum mechanical methods. It crystallises in the monoclinic space group P21/n with a = 4.844(3), b = 21.428(2), c = 13.726(2) Å, ß = 93.07(2)° (R1 =0.032 for 4132 reflections [I > 2σ(I)]). The title compound is not planar and an intramolecular hydrogen bond connects O1 and N1 [2.530(4) Å]. Complementary IR, 1H NMR and UV measurements out. Tautomerism and conformations of the title semi-empirical quantum mechanical calculations and the results are compared with the X-ray data.

The Dichloroplatinum(II) Complex of 5,5,7-Trimethyl-1,4-diazacycloheptane: Preparation, Crystal Structure and Binding to Nucleotides and DNA

1998 ◽  
Vol 51 (11) ◽  
pp. 977 ◽  
Author(s):  
Chih-Lynne Teo ◽  
Ronald R. Fenton ◽  
Peter Turner ◽  
Trevor W. Hambley
Keyword(s):  
Crystal Structure ◽  
Dna Binding ◽  
Molecular Mechanics ◽  
X Ray Diffraction ◽  
Binding Studies ◽  
Triclinic Space Group ◽  
X Ray ◽  
Dna Binding Studies ◽  
Total Dna ◽  
R Value

The preparation of [Pt(tmdz)Cl2] (tmdz = 5,5,7-trimethyl-1,4-diazacycloheptane) is described. The crystal structure has been determined by X-ray diffraction methods and refined to an R value of 0·048 (764F). The crystals are triclinic, space group P -1, a 8·023(2), b 10·874(4), c 14·207(3) Å, α 95·34(3), β 94·96(2), γ 94·97(3)°. N.m.r. studies and molecular mechanics methods show that only one diastereomer of the complex—that observed in the crystal structure—is energetically accessible. In total DNA binding studies, [Pt(tmdz)Cl2] binds less effectively and at a lower rate than cisplatin. The complex reacts with dG and d(GpG) to form a variety of isomeric products, as indicated by h.p.l.c. analysis.

A Simple, One-Pot Synthesis of Trans-Substituted Spiro [5,5] undecane-1,5,9-triones with Aromatic Aldehydes and Meldrum's Acid as the Starting Materials

2015 ◽  
Vol 68 (10) ◽  
pp. 1599 ◽  
Author(s):  
Jingping Ou-Yang ◽  
Yu Zhao ◽  
Huailei Jiang ◽  
Lingxin Meng ◽  
Xingshu Li ◽  
...  
Keyword(s):  
1H Nmr ◽  
Aromatic Aldehydes ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Meldrum's Acid ◽  
X Ray Diffraction ◽  
Meldrum’S Acid ◽  
Reaction Conditions ◽  
One Pot ◽  
X Ray

A simple, one-pot process for the construction of substituted spiro[5,5]undecane-1,5,9-triones using aromatic aldehydes and Meldrum’s acid, and aniline as a catalyst, is reported. Fifteen compounds were synthesized, and the trans/cis ratios were calculated based on 1H NMR analyses of the unpurified products. Quantum mechanical calculations and X-ray diffraction were undertaken to identify the configuration of compound 2a. The proposed mechanisms for these reactions are presented in this paper. In contrast to previous literature, this method endows excellent diastereoselectivity to a series of trans-substituted derivatives. The method is characterized by its simple operation, commercial availability of all materials, mild reaction conditions and moderate-to-good chemical yields.

Determination of the Crystal Structure of Isotacticcis-1,4-Poly(1,3-hexadiene) by X-Ray Diffraction and Molecular Mechanics

2008 ◽  
Vol 209 (10) ◽  
pp. 1012-1020 ◽  
Author(s):  
Beniamino Pirozzi ◽  
Roberto Napolitano ◽  
Giovangiuseppe Giusto ◽  
Giovanni Ricci
Keyword(s):  
Crystal Structure ◽  
Molecular Mechanics ◽  
X Ray Diffraction ◽  
X Ray

Determination of the Crystal Structure of Syndiotactic 1,2-Poly(E-3-methyl-1,3-pentadiene) by X-ray Diffraction and Molecular Mechanics

2007 ◽  
Vol 40 (25) ◽  
pp. 8962-8968 ◽  
Author(s):  
Beniamino Pirozzi ◽  
Roberto Napolitano ◽  
Giovangiuseppe Giusto ◽  
Simona Esposito ◽  
Giovanni Ricci
Keyword(s):  
Crystal Structure ◽  
Molecular Mechanics ◽  
X Ray Diffraction ◽  
X Ray

Determination of the Crystal Structure of Syndiotactic 3,4-Poly(2-methyl-1,3-butadiene) by Molecular Mechanics and X-Ray Diffraction

2004 ◽  
Vol 205 (10) ◽  
pp. 1343-1350 ◽  
Author(s):  
Beniamino Pirozzi ◽  
Roberto Napolitano ◽  
Vittorio Petraccone ◽  
Simona Esposito
Keyword(s):  
Crystal Structure ◽  
Molecular Mechanics ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Interpreting Disordered PXRD Structures using Molecular Dynamics

2014 ◽  
Vol 70 (a1) ◽  
pp. C1569-C1569
Author(s):  
Kristoffer Johansson ◽  
Xiaozhou Li ◽  
Andrew Bond ◽  
Jacco van de Streek
Keyword(s):  
Molecular Dynamics ◽  
Structural Information ◽  
Supplementary Information ◽  
Rational Approach ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Properties ◽  
Solid Form

A central topic in the formulation of solid medicinal products is the identification of a suitable solid form of an active compound to obtain optimal physicochemical properties. To this end, disorder may be important for relevant crystal properties like stability. For example, disorder may account for more than 10% of the crystal volume. A rational approach to solid-form selection is typically based on structural information at atomic resolution. In practice, pharmaceutical compounds are not always well-behaved and especially in the study of polymorphs or compounds with flexible groups it can be challenging to obtain crystals suitable for single-crystal X-ray diffraction. Powder X-ray diffraction (PXRD) is a popular alternative, but it generally requires supplementary information like molecular connectivity in simple cases or computational models to solve larger structures. Computational modeling has come a long way and accurate and reliable structures of pharmaceutically relevant compounds can indeed be obtained using laboratory PXRD measurements and quantum-mechanical calculations [1]. The major limitation of quantum mechanical calculations, however, is that they do not consider time nor temperature but only static structures at zero temperature. Thus, these methods cannot model phenomena related to disorder. The molecular dynamics (MD) method can add temperature as well as time and spatial resolution to a model and has in recent years developed to be a scalable, reliable and increasingly available technique. As more and more groups from academia as well as industry employ MD in their work, the development will increase to gain momentum in the coming years. We use MD in a high-performance setting to study crystal properties that are relevant for pharmaceutical research. Using a combination of models from first principles and MD we are able to study highly disordered structures and polymorphs on the basis of PXRD data.

Stereochemistry of α-Amino Oximes From the Monoterpene Hydrocarbons Car-3-ene, Limonene and α-Pinene

1992 ◽  
Vol 45 (6) ◽  
pp. 1077 ◽  
Author(s):  
AV Tkachev ◽  
AV Rukavishnikov ◽  
AM Chibiryaev ◽  
AY Denisov ◽  
YV Gatilov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Molecular Mechanics ◽  
High Field ◽  
Crystallographic Analysis ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Molecular Mechanics Calculations ◽  
Space Group ◽  
X Ray ◽  
Monoterpene Hydrocarbons

The conformation and configuration of the α-amino oximes derived from the terpene hydrocarbons car-3-ene, limonene and α- pinene have been determined by n.m.r. spectroscopy (high-field 1H n.m.r., 13C n.m.r., INADEQUATE technique), molecular mechanics calculations and X-ray crystallographic analysis. The crystal structure of (lS,3S,6R)-3-dimethylamino-caran-4-one (E)-oxime has been determined by X-ray diffraction; crystals are orthorhombic, space group P 212121 with a 11.421(2), b 13.223(2), c 16.992(4) �, Z 8. Refinement on 1730 observed reflections measured with Cu K α radiation converged at R 0.053.

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