scholarly journals Crystal Packing and Supramolecular Motifs in Four Phenoxyalkanoic Acid Herbicides—Low-Temperature Redeterminations

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Lesław Sieroń ◽  
Joanna Kobyłecka ◽  
Anna Turek
Keyword(s):  
Low Temperature ◽  
Propionic Acid ◽  
Crystal Packing ◽  
Dichlorophenoxyacetic Acid ◽  
X Ray ◽  
Π Interactions ◽  
X Ray Crystallography ◽  
Supramolecular Motifs ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Acid Herbicides

A low-temperature redetermination by X-ray crystallography of four phenoxyalkanoic acid herbicides, 4-chloro-2-methylphenoxyacetic acid (MCPA), rac-2-(4-chloro-2-methylphenoxy)propionic acid (MCPP), 2,4-dichlorophenoxyacetic acid (2,4-D), and 2,4-dichlorophenoxybutyric acid (2,4-DB), allowed the supramolecular structures of these compounds to be precisely described in terms of C⋯O/C–H⋯π interactions. The geometric parameters of the redetermined structures agree with those previously reported, but with improved precision.

scholarly journals Solvent Effects on the Spin Crossover Properties of Iron(II) Imidazolylimine Complexes

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 116 ◽  
Author(s):  
Darunee Sertphon ◽  
Phimphaka Harding ◽  
Keith Murray ◽  
Boujemaa Moubaraki ◽  
Suzanne Neville ◽  
...  
Keyword(s):  
Low Temperature ◽  
Hydrogen Bonds ◽  
Solvent Effects ◽  
Spin Crossover ◽  
Magnetic Measurements ◽  
X Ray ◽  
Π Interactions ◽  
X Ray Crystallography ◽  
Solvent Loss

A series of Fe(II) complexes, fac-[Fe(4-ima-Bp)3](Y)2⋅sol (Y = ClO4; sol = 3EtOH 1, 3MeOH 2; Y= BF4; sol = EtOH⋅4H2O 3, 4H2O 4 and 3.5MeCN 5) have been prepared and structurally and magnetically characterized. The low temperature structures of 1, 2 and 5 have been determined by X-ray crystallography with LS Fe(II) centres found in all cases. Extensive C–H···π interactions between the cations form 2D layers, which are linked to one another through N-H···O and O-H···O hydrogen bonds, resulting in high cooperativity. Despite 5 containing MeCN, N-H···O/F hydrogen bonds, and C–H···π and π-π interactions combine to give similar 2D layers. Magnetic measurements reveal moderately abrupt spin crossover for 1-4; becoming more gradual and only 50% complete in 1 due to solvent loss. The MeCN solvate shows more gradual SCO and reinforces how subtle changes in packing can significantly influence SCO behaviour.

Systhesis, Characterization and Spectroscopic Properties of (2E,6E)-2,6-Bis(2,3,4-tri-methoxy-benzylidene)cyclohexanone

2011 ◽  
Vol 396-398 ◽  
pp. 2338-2341
Author(s):  
Xing Chuan Wei ◽  
Zhi Li Liu ◽  
Kun Zhang ◽  
Zhi Yun Du ◽  
Xi Zheng
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Spectroscopic Properties ◽  
Spectral Studies ◽  
Double Bonds ◽  
X Ray ◽  
Π Interactions ◽  
X Ray Crystallography

In this paper, (2E,6E)-2,6-Bis(2,3,4-tri-methoxy -benzylidene)cyclohexanone (omitted as tmbcho) (1) was obtained by the reaction of acetic acid, tetrahydrofuran, cyclohexanone and 2,3,4-tri-methoxy-benzaldehyde. Three non-classic hydrogen bonds were observed in the compound. X-ray crystallography shows that the crystal structure is stabilized by intermolecular C-H•••π interactions and it contains plenty of conjugated double bonds. The title compound was characterized by UV-vis and fluorescent spectral studies.

scholarly journals Evaluation of Hydrocalumite-Like Compounds as Catalyst Precursors in the Photodegradation of 2,4-Dichlorophenoxyacetic Acid

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Manuel Sánchez-Cantú ◽  
Clara Barcelos-Santiago ◽  
Claudia M. Gomez ◽  
Esthela Ramos-Ramírez ◽  
Ma. de Lourdes Ruiz Peralta ◽  
...  
Keyword(s):  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Nitrogen Adsorption ◽  
Dichlorophenoxyacetic Acid ◽  
X Ray ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Adsorption Desorption ◽  
Oxide Ions ◽  
Environmentally Friendly Method ◽  
Simple Economic

Three hydrocalumite-like compounds in a Ca/Al ratio of 2 containing nitrate and acetate anions in the interlaminar region were prepared by a simple, economic, and environmentally friendly method. The solids were characterized by X-ray powder diffraction (XRD), thermogravimetric (TG) analysis, nitrogen adsorption-desorption at −196°C, scanning electron microscopy (SEM), infrared spectroscopy (FTIR), and UV-Vis Diffuse Reflectance Spectroscopy (DRS). The catalytic activity of the calcined solids at 700°C was tested in the photodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) where 57% degradation of 2,4-D (40 ppm) and a mineralization percentage of 60% were accomplished within 150 minutes. The photocatalytic properties were attributed to mayenite hydration, since the oxide ions in the cages are capable of reacting with water to form hydroxide anions capable of breaking down the 2,4-D molecules.

A Zinc(II)-Silver(I) Bimetallic Coordination Polymer Assembled Through Argentophilic and π-π Interactions, f[Zn(phen)2(H2O) {Ag(CN)2g][Ag(CN)2]·MeOH}n (phen=1,10-Phenanthroline)

2013 ◽  
Vol 68 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Muhammad Monim-ul-Mehbooba ◽  
Muhammad Ramzan ◽  
Tobias Rüffe ◽  
Heinrich Lang ◽  
Shafqat Naddem ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Analysis ◽  
Ir Spectroscopy ◽  
Coordination Polymer ◽  
Hydrogen Bonds ◽  
X Ray ◽  
Π Interactions ◽  
X Ray Crystallography ◽  
3D Network ◽  
Argentophilic Interactions

A cyanido-bridged Zn(II)-Ag(I) bimetallic coordination polymer, {[Zn(phen)2(H2O){Ag(CN)2}] [Ag(CN)2]·MeOH}n (1), was prepared using ZnCl2, 1,10-phenanthroline (phen) and K[Ag(CN)2] and characterized by IR spectroscopy, thermal analysis and X-ray crystallography. The crystal structure of 1 consists of dinuclear [Zn(phen)2(H2O){Ag(CN)2}]+ cations, [Ag(CN)2]- anions and a methanol molecule. The non-coordinated [Ag(CN)2]- anions are linked to the [Zn(phen)2(H2O){Ag(CN)2}]+ complex cations through argentophilic interactions leading to the formation of chains. The chains are connected by hydrogen bonds and π-π interactions to give a 3D network.

scholarly journals A hybrid approach reveals the allosteric regulation of GTP cyclohydrolase I

2020 ◽  
Vol 117 (50) ◽  
pp. 31838-31849
Author(s):  
Rebecca Ebenhoch ◽  
Simone Prinz ◽  
Susann Kaltwasser ◽  
Deryck J. Mills ◽  
Robert Meinecke ◽  
...  
Keyword(s):  
Crystal Packing ◽  
Substrate Binding ◽  
Regulatory Protein ◽  
Allosteric Regulation ◽  
Hybrid Approach ◽  
Site Directed Mutagenesis ◽  
Gtp Cyclohydrolase I ◽  
Gtp Cyclohydrolase ◽  
X Ray ◽  
X Ray Crystallography

Guanosine triphosphate (GTP) cyclohydrolase I (GCH1) catalyzes the conversion of GTP to dihydroneopterin triphosphate (H2NTP), the initiating step in the biosynthesis of tetrahydrobiopterin (BH4). Besides other roles, BH4 functions as cofactor in neurotransmitter biosynthesis. The BH4 biosynthetic pathway and GCH1 have been identified as promising targets to treat pain disorders in patients. The function of mammalian GCH1s is regulated by a metabolic sensing mechanism involving a regulator protein, GCH1 feedback regulatory protein (GFRP). GFRP binds to GCH1 to form inhibited or activated complexes dependent on availability of cofactor ligands, BH4 and phenylalanine, respectively. We determined high-resolution structures of human GCH1−GFRP complexes by cryoelectron microscopy (cryo-EM). Cryo-EM revealed structural flexibility of specific and relevant surface lining loops, which previously was not detected by X-ray crystallography due to crystal packing effects. Further, we studied allosteric regulation of isolated GCH1 by X-ray crystallography. Using the combined structural information, we are able to obtain a comprehensive picture of the mechanism of allosteric regulation. Local rearrangements in the allosteric pocket upon BH4 binding result in drastic changes in the quaternary structure of the enzyme, leading to a more compact, tense form of the inhibited protein, and translocate to the active site, leading to an open, more flexible structure of its surroundings. Inhibition of the enzymatic activity is not a result of hindrance of substrate binding, but rather a consequence of accelerated substrate binding kinetics as shown by saturation transfer difference NMR (STD-NMR) and site-directed mutagenesis. We propose a dissociation rate controlled mechanism of allosteric, noncompetitive inhibition.

Substituent position effect on the crystal structures of N-phenyl-2-phthalimidoethanesulfonamide derivatives

2018 ◽  
Vol 74 (1) ◽  
pp. 31-36
Author(s):  
Resul Sevinçek ◽  
Duygu Barut Celepci ◽  
Serap Köktaş Koca ◽  
Özlem Akgül ◽  
Muittin Aygün
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Packing ◽  
Biological Activities ◽  
Position Effect ◽  
Intermolecular Hydrogen Bond ◽  
X Ray ◽  
Space Groups ◽  
X Ray Crystallography ◽  
Hydrogen Bond Interactions ◽  
The Impact

In order to determine the impact of different substituents and their positions on intermolecular interactions and ultimately on the crystal packing, unsubstituted N-phenyl-2-phthalimidoethanesulfonamide, C16H14N2O4S, (I), and the N-(4-nitrophenyl)-, C16H13N3O6S, (II), N-(4-methoxyphenyl)-, C16H16N3O6S, (III), and N-(2-ethylphenyl)-, as the monohydrate, C18H18N2O4S·H2O, (IV), derivatives have been characterized by single-crystal X-ray crystallography. Sulfonamides (I) and (II) have triclinic crystal systems, while (III) and (IV) are monoclinic. Although the molecules differ from each other only with respect to small substituents and their positions, they crystallized in different space groups as a result of differing intra- and intermolecular hydrogen-bond interactions. The structures of (I), (II) and (III) are stabilized by intermolecular N—H...O and C—H...O hydrogen bonds, while that of (IV) is stabilized by intermolecular O—H...O and C—H...O hydrogen bonds. All four structures are of interest with respect to their biological activities and have been studied as part of a program to develop anticonvulsant drugs for the treatment of epilepsy.

Liquid Chromatography of Liquid Formulations Containing 2,4-Dichlorophenoxyacetic Acid, Dicamba, and 2-(2-Methyl-4-chlorophenoxy)propionic Acid as Their Salts

1983 ◽  
Vol 66 (5) ◽  
pp. 1220-1225 ◽  
Author(s):  
Robert B Grorud ◽  
John E Forrette
Keyword(s):  
Propionic Acid ◽  
Internal Standard ◽  
Solvent System ◽  
Dichlorophenoxyacetic Acid ◽  
Binary Solvent ◽  
Internal Standards ◽  
Liquid Chromatographic Method ◽  
Standard Solution ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Liquid Chromatographic

Abstract A high pressure liquid chromatographic method has been developed for liquid herbicide combinations that contain different combinations of 3 active ingredients including 2,4-dichlorophenoxyacetic acid (2,4-D), 2-(2-methyl-4-chlorophenoxy)propionic acid (MCPP), and dicamba. A reverse phase column in the ion suppression mode and a binary solvent system separate all 3 herbicides quantitatively on a single chromatogram. The internal standard solution may contain 2 internal standards, salicylic acid and butyrophenone, for use with certain combinations of the herbicides. The solvent system resolves the compounds of interest from all significant impurities.

Application of the Variable Oxygen Probe to Determine the π-Electron Donor Ability of the Alkyne Group

2014 ◽  
Vol 67 (12) ◽  
pp. 1866 ◽  
Author(s):  
Benjamin L. Harris ◽  
Jonathan M. White
Keyword(s):  
Low Temperature ◽  
Electron Donor ◽  
Oxygen Probe ◽  
X Ray ◽  
X Ray Crystallography ◽  
Donor Ability ◽  
Structural Database ◽  
Derivatives Of ◽  
Electron Demand ◽  
Electron Donor Ability

Eight ester and ether derivatives of propargyl alcohol with varying electron demand were structurally characterised using low temperature X-ray crystallography, these were combined with seven derivatives obtained from the Cambridge Structural Database. Variable oxygen probe analysis of these derivatives provided evidence that the ethynyl substituent is a relatively weak π-electron donor, and is a slightly less effective donor than the C–C bond of an ethyl substituent.

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