The Conformation of Crystalline Di[3-(4'-methoxyphenyl)-2,2,4,4-tetramethylpentan-3-yl] Oxalate

1996 ◽  
Vol 49 (10) ◽  
pp. 1171 ◽  
Author(s):  
DJ Collins ◽  
M Dosen ◽  
GD Fallon ◽  
HA Jacobs ◽  
GF Meijs ◽  
...  
Keyword(s):  
Benzene Ring ◽  
X Ray ◽  
X Ray Crystallography ◽  
Tetrahydropyranyl Ether ◽  
Relationship Of

Di [3-(4'-methoxyphenyl)-2,2,4,4-tetramethylpentan-3-yl] oxalate (4a) and the analogous bis tetrahydropyranyl ether (4b) have been synthesized, and X-ray crystallography of the former shows an almost symmetrically staggered relationship of the t-butyl groups with respect to the plane of the benzene ring.

The Reaction of Some N-(Nitrophenyl)azoles With Alkali: Preparation of the Corresponding Azoxybenzenes. X-Ray Structure of 2,2′-Bis(1″,2″,4″-triazol-1″-yl)azoxybenzene

1993 ◽  
Vol 46 (4) ◽  
pp. 417 ◽  
Author(s):  
MF Mackay ◽  
GJ Trantino ◽  
JFK Wilshire
Keyword(s):  
Solid State ◽  
Benzene Ring ◽  
Dihedral Angle ◽  
Experimental Error ◽  
Potassium Hydroxide ◽  
Potassium Hydroxide Solution ◽  
Triazole Ring ◽  
X Ray ◽  
X Ray Crystallography ◽  
Weak Electron

The reactions of some representative N-( nitrophenyl )azoles with boiling aqueous ethanolic potassium hydroxide solution gave the corresponding bis ( azolyl ) azoxybenzenes . It is deduced that, in these reactions, the N-attached azolyl groups concerned are acting as weak electron-withdrawing groups. The structure of 2,2′-bis(1″,2″,4″-triazol-1″-yl) azoxybenzene was determined in the solid state by X-ray crystallography. The monoclinic crystals belong to the space group P21/c with a 8.815(1), b 7.863(1), c 11.836(1) Ǻ, β 109.96(1)° and Z 2. The structure was refined to an R index of 0.041 for 1172 observed terms. The midpoint of the exocyclic N=N bond lies on an inversion centre so that the azoxy oxygen is statistically distributed between two sites. The benzene ring atoms are coplanar to within experimental error, as are the triazole ring atoms, and the dihedral angle between the perpendiculars to the two rings is 35.3(3)°.

scholarly journals Adamantane-Functionalized Phthalimide Scaffold: Pathways to Supramolecular Interactions and Drug Discovery

Organics ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 388-394
Author(s):  
Hamidou Keita
Keyword(s):  
Crystal Structure ◽  
Drug Discovery ◽  
Single Crystal ◽  
Benzene Ring ◽  
Driving Force ◽  
Core Structure ◽  
Supramolecular Interactions ◽  
The Novel ◽  
X Ray ◽  
X Ray Crystallography

Herein, the synthesis of a novel adamantanyl-functionalized phthalimide scaffold is demonstrated. The novel compound could be used as a precursor for various synthetic pathways owing to the generic use of adamantane substituents as the driving force for supramolecular interactions with macrocycles and N-substituted phthalimide derivatives as a core structure in numerous drugs. The adamantanyl-functionalized phthalimide scaffold contains bromide groups on the C4 and C5 positions of the benzene ring, effectively allowing further facile modifications of the scaffold. The structure was fully characterized including single-crystal X-ray crystallography. The crystal structure shows an adamantane moiety at an angle of 115.57(7)° to the phthalimide core, hence sterically freeing the adamantane unit for host–guest interactions.

Preparation and X-ray crystal structures of the arsenic pentafluoride adducts of benzo-2,1,3-thiadiazole and benzo-1,2,3-thiadiazole

1986 ◽  
Vol 64 (5) ◽  
pp. 849-853 ◽  
Author(s):  
Allen Apblett ◽  
Tristram Chivers ◽  
John F. Richardson
Keyword(s):  
Nitrogen Atom ◽  
Crystal Structures ◽  
Benzene Ring ◽  
Heterocyclic Ring ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
C Nmr

The reaction of arsenic pentafluoride with benzo-2,1,3-thiadiazole, 1, or benzo-1,2,3-thiadiazole, 2, in liquid SO2 gave 1:1 adducts that were characterized spectroscopically (infrared and 13C nmr) and by X-ray crystallography. Crystal data: for 1•AsF5, monoclinic, space group P21/n, a = 6.932(1), b = 9.113(1), c = 15.136(2) Å, β = 98.035(7)°, V = 946.8(2) Å3, Z = 4; for 2•AsF5, monoclinic, space group P21/a, a = 7.573(2), b = 13.101(2), c = 9.514(3) Å, β = 90.95(2)°, V = 943.9(4) Å3, Z = 4. The coordination of AsF5 to one of the nitrogen atoms in 1 introduces asymmetry in the heterocyclic ring, with the longer bond lengths being associated with the coordinated nitrogen atom, d(S—N) = 1.633(5) and 1.577(6) Å, d(C—N) = 1.364(7) and 1.339(8) Å. The quinonoid character of the benzene ring is still apparent in the adduct. In 2•AsF5, the AsF5 molecule is coordinated to the nitrogen atom that is bonded to carbon.

Structure and wavelength modification in retinylidene iminium salts

1996 ◽  
Vol 74 (4) ◽  
pp. 591-601 ◽  
Author(s):  
George R. Elia ◽  
Ronald F. Childs ◽  
James F. Britten ◽  
Daniel S.C. Yang ◽  
Bernard D. Santarsiero
Keyword(s):  
Solid State ◽  
Alkyl Substituent ◽  
Spectroscopic Properties ◽  
Crystal Lattices ◽  
Charge Delocalization ◽  
X Ray ◽  
X Ray Crystallography ◽  
Iminium Salts ◽  
Internuclear Distances ◽  
Relationship Of

The spectroscopic and structural properties of the perchlorate and triflate salts of N-n-butyl-retinylidene imine, 2 and 3, have been examined in solution and solid phases. In solution these salts were found to exhibit very similar UV and NMR spectroscopic properties. However, in the solid state marked differences in their absorption spectra (2, λmax = 504 nm; 3, λmax = 445 nm) and 13C NMR spectra were found. The structures of the two salts were determined by X-ray crystallography. The cations in each of the salts were shown to have very similar conformations, detailed structures, and packing in their crystal lattices. The differences in the spectroscopic properties of the salts in the solid state could not be accounted for on the basis of any structural differences in the cations themselves. In terms of cation–anion interactions, a strong hydrogen bonding interaction was found in each case between the N-H proton and an oxygen atom of the counterion. However, there were significant differences between the two salts in terms of the [Formula: see text] internuclear distances (2, [Formula: see text] and in 3, 2.85(1) Å). The results are strongly suggestive that the wavelength and positive charge delocalization in retinylidène iminium salts are controlled by variation of the distance between the anion and the proton bonded to the Schiff base nitrogen atom. The work reported here represents the first examples of secondary retinylidene iminium salts containing an N-alkyl substituent to be successfully analyzed by X-ray crystallography. The relationship of these observations in the solid state to the spectroscopic properties of the natural visual pigments is explored. Key words: retinylidène iminium salts, iminium salts, cation–anion interactions.

scholarly journals Identification of SARS-CoV2 Main Protease Coldspots Suitable for Drug Targeting

2020 ◽  
Author(s):  
Navaneethakrishnan Krishnamoorthy ◽  
Khalid Fakhro
Keyword(s):  
Active Site ◽  
Missense Mutations ◽  
The Novel ◽  
X Ray ◽  
X Ray Crystallography ◽  
Main Protease ◽  
New Perspective ◽  
Function Relationship ◽  
Novel Coronavirus ◽  
Relationship Of

Abstract Most attempts to target the novel coronavirus SARS-CoV2 are focusing on the main protease (Mpro) 1,2. We already have access to high resolution 3D-structures of the SARS-CoV2 Mpro, which were developed with inhibitors as co-crystals using X-ray crystallography 3-9. However, >19,000 missense mutations in the Mpro have already been reported 10. The mutations encompassing 282 amino acid positions and these “hotspots” might change the Mpro structure and activity, potentially rendering novel antivirals and vaccines ineffective. Here we identified 24 mutational “coldspots” that have resisted mutation since the virus was first detected. We compared the structure-function relationship of these coldspots with several SARS-CoV2 Mpro X-ray crystal structures. We found that three coldspot residues (Leu141, Phe185 and Gln192) help to form the active site, while six (Gly2, Arg4, Tyr126, Lys137, Leu141 and Leu286) contribute to dimer formation that is required for Mpro activity. Importantly, seven coldpots are conserved among other coronaviruses and available on the surface of the active site and at the dimer interface for targeting. The identification and short list of these coldspots offers a new perspective to target the SARS-CoV2 Mpro while avoiding mutation-based drug resistance.

Molecular Structures of p-Methylsulphonylbenzoic Acid and Methylphenylsulphone: Comparison of X-Ray and Electron Diffraction Results

1984 ◽  
Vol 39 (5) ◽  
pp. 607-609 ◽  
Author(s):  
Jon Brunvoll ◽  
Marcello Colapietro ◽  
Aldo Domenicano ◽  
Clara Marciante ◽  
Gustavo Portalone ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Benzene Ring ◽  
Bond Distance ◽  
Molecular Structures ◽  
Gas Electron Diffraction ◽  
Free Molecule ◽  
X Ray ◽  
Bond Angles ◽  
X Ray Crystallography ◽  
Systematic Effects

The molecular structures of p-methylsulphonylbenzoic acid and methylphenylsulphone have been accurately determined by X-ray crystallography and gas electron diffraction, respectively. After correction for systematic effects, the geometry of the crystal molecule is seen to agree with that of the free molecule within a few thousandths of an Å unit for bond distances and a few tenths of a degree for bond angles. An exception is the S-Me bond distance, which is ca. 0.02 Å shorter in the crystal. The distortion of the benzene ring angles from 120°, an effect of the - SO2Me substituent, is virtually the same from both experiments

Synthesis of (±)-14-epi-hydroxydolasta-1(15),7,9-triene and (±)-7-epi-acetoxy-14-epi-hydroxydolasta-1(15),8-diene*Taken in part from the Ph.D. dissertation of Jianhua Yu, University of Georgia, Athens, Georgia, USA, 2009.

2012 ◽  
Vol 90 (1) ◽  
pp. 75-84 ◽  
Author(s):  
George Majetich ◽  
Jianhua Yu
Keyword(s):  
Methyl Groups ◽  
Cyclization Product ◽  
Facile Synthesis ◽  
X Ray ◽  
X Ray Crystallography ◽  
University Of Georgia ◽  
Salient Features ◽  
Relationship Of

1,3-Dimethyl-2-nitrobenzene was converted to the key intramolecular Friedel–Crafts intermediate 24 in ten steps. Treatment of 24 with TiCl4 produced tricyclic enone 25 in 61%–75% yield, having the requisite trans relationship of the two angular methyl groups and many of the salient features of the dolastane diterpenes. The structure of enone 25 was verified by X-ray crystallography analysis. Cyclization product 25 permitted the facile synthesis of (±)-14-epi-hydroxydolasta-1(15),7,9-triene and (±)-7-epi-acetoxy-14-epi-hydroxydolasta-1(15),8-diene, which are detailed in this article.

scholarly journals Heavy Atom Detergent/Lipid Combined X-ray Crystallography for Elucidating the Structure-Function Relationships of Membrane Proteins

Membranes ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 823
Author(s):  
Shinya Hanashima ◽  
Takanori Nakane ◽  
Eiichi Mizohata
Keyword(s):  
Membrane Proteins ◽  
Structure Function ◽  
New Technologies ◽  
Heavy Atom ◽  
Protein Structures ◽  
X Ray ◽  
X Ray Crystallography ◽  
Function Relationship ◽  
And Function ◽  
Relationship Of

Membrane proteins reside in the lipid bilayer of biomembranes and the structure and function of these proteins are closely related to their interactions with lipid molecules. Structural analyses of interactions between membrane proteins and lipids or detergents that constitute biological or artificial model membranes are important for understanding the functions and physicochemical properties of membrane proteins and biomembranes. Determination of membrane protein structures is much more difficult when compared with that of soluble proteins, but the development of various new technologies has accelerated the elucidation of the structure-function relationship of membrane proteins. This review summarizes the development of heavy atom derivative detergents and lipids that can be used for structural analysis of membrane proteins and their interactions with detergents/lipids, including their application with X-ray free-electron laser crystallography.

Difference Fourier Analysis of Glucose Embedded and Frozen Hydrated Purple Membrane

1982 ◽  
Vol 40 ◽  
pp. 74-75
Author(s):  
Jules S. Jaffe ◽  
Robert M. Glaeser
Keyword(s):  
Purple Membrane ◽  
Data Set ◽  
High Resolution Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
Fourier Techniques ◽  
Versus Protein ◽  
The Difference ◽  
Difference Fourier ◽  
Ideal Method

Although difference Fourier techniques are standard in X-ray crystallography it has only been very recently that electron crystallographers have been able to take advantage of this method. We have combined a high resolution data set for frozen glucose embedded Purple Membrane (PM) with a data set collected from PM prepared in the frozen hydrated state in order to visualize any differences in structure due to the different methods of preparation. The increased contrast between protein-ice versus protein-glucose may prove to be an advantage of the frozen hydrated technique for visualizing those parts of bacteriorhodopsin that are embedded in glucose. In addition, surface groups of the protein may be disordered in glucose and ordered in the frozen state. The sensitivity of the difference Fourier technique to small changes in structure provides an ideal method for testing this hypothesis.

3-D reconstruction of molecular shape from microcrystal thin sections

1983 ◽  
Vol 41 ◽  
pp. 748-749
Author(s):  
S. Cusack ◽  
J.-C. Jésior
Keyword(s):  
Three Dimensional ◽  
Molecular Shape ◽  
Biological Molecules ◽  
Fourier Space ◽  
Single Particles ◽  
Thin Sections ◽  
Standard Methods ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dimensional Reconstruction

Three-dimensional reconstruction techniques using electron microscopy have been principally developed for application to 2-D arrays (i.e. monolayers) of biological molecules and symmetrical single particles (e.g. helical viruses). However many biological molecules that crystallise form multilayered microcrystals which are unsuitable for study by either the standard methods of 3-D reconstruction or, because of their size, by X-ray crystallography. The grid sectioning technique enables a number of different projections of such microcrystals to be obtained in well defined directions (e.g. parallel to crystal axes) and poses the problem of how best these projections can be used to reconstruct the packing and shape of the molecules forming the microcrystal.Given sufficient projections there may be enough information to do a crystallographic reconstruction in Fourier space. We however have considered the situation where only a limited number of projections are available, as for example in the case of catalase platelets where three orthogonal and two diagonal projections have been obtained (Fig. 1).

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