A charge-transfer salt composed of methyl viologen and hexacyanidoferrate(II)

2017 ◽  
Vol 73 (6) ◽  
pp. 476-480 ◽  
Author(s):  
Rikako Tanaka ◽  
Nobuyuki Matsushita
Keyword(s):  
Crystal Structure ◽  
Charge Transfer ◽  
Electron Acceptor ◽  
Methyl Viologen ◽  
Water Molecules ◽  
Asymmetric Unit ◽  
Hydrated Salt ◽  
Cyanide Ligands ◽  
A Charge

The methyl viologen dication, used under the name Paraquat as an agricultural reagent, is a well-known electron-acceptor species that can participate in charge-transfer (CT) interactions. The determination of the crystal structure of this species is important for accessing the CT interaction and CT-based properties. The title hydrated salt, bis(1,1′-dimethyl-4,4′-bipyridine-1,1′-diium) hexacyanidoferrate(II) octahydrate, (C12H14N2)2[Fe(CN)6]·8H2O or (MV)2[Fe(CN)6]·8H2O [MV2+ is the 1,1′-dimethyl-4,4′-bipyridine-1,1′-diium (methyl viologen) dication], crystallizes in the space group P21/c with one MV2+ cation, half of an [Fe(CN)6]4− anion and four water molecules in the asymmetric unit. The FeII atom of the [Fe(CN)6]4− anion lies on an inversion centre and has an octahedral coordination sphere defined by six cyanide ligands. The MV2+ cation is located on a general position and adopts a noncoplanar structure, with a dihedral angle of 40.32 (7)° between the planes of the pyridine rings. In the crystal, layers of electron-donor [Fe(CN)6]4− anions and layers of electron-acceptor MV2+ cations are formed and are stacked in an alternating manner parallel to the direction of the −2a + c axis, resulting in an alternate layered structure.

scholarly journals Kinetic and chemical analyses of the cytokinin dehydrogenase-catalysed reaction: correlations with the crystal structure

2006 ◽  
Vol 398 (1) ◽  
pp. 113-124 ◽  
Author(s):  
Hana Popelková ◽  
Marco W. Fraaije ◽  
Ondřej Novák ◽  
Jitka Frébortová ◽  
Kristin D. Bilyeu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Charge Transfer ◽  
Electron Acceptor ◽  
Flow Analysis ◽  
Reduction Rate ◽  
High Rate ◽  
Side Chain ◽  
Binary Complex ◽  
Cytokinin Dehydrogenase ◽  
A Charge

CKX (cytokinin dehydrogenase) is a flavoprotein that cleaves cytokinins to adenine and the corresponding side-chain aldehyde using a quinone-type electron acceptor. In the present study, reactions of maize (Zea mays) CKX with five different substrates (N6-isopentenyladenine, trans-zeatin, kinetin, p-topolin and N-methyl-isopentenyladenine) were studied. By using stopped-flow analysis of the reductive half-reaction, spectral intermediates were observed indicative of the transient formation of a binary enzyme–product complex between the cytokinin imine and the reduced enzyme. The reduction rate was high for isoprenoid cytokinins that showed formation of a charge-transfer complex of reduced enzyme with bound cytokinin imine. For the other cytokinins, flavin reduction was slow and no charge-transfer intermediates were observed. The binary complex of reduced enzyme and imine product intermediate decays relatively slowly to form an unbound product, cytokinin imine, which accumulates in the reaction mixture. The imine product only very slowly hydrolyses to adenine and an aldehyde derived from the cytokinin N6 side-chain. Mixing of the substrate-reduced enzyme with Cu2+/imidazole as an electron acceptor to monitor the oxidative half-reaction revealed a high rate of electron transfer for this type of electron acceptor when using N6-isopentenyladenine. The stability of the cytokinin imine products allowed their fragmentation analysis and structure assessment by Q-TOF (quadrupole–time-of-flight) MS/MS. Correlations of the kinetic data with the known crystal structure are discussed for reactions with different cytokinins.

scholarly journals The 2:1 charge-transfer complex of 4,6-dimethyldibenzothiophene and 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane

IUCrData ◽  
2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Takuya Fujii ◽  
Hideo Yamakado
Keyword(s):  
Charge Transfer ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Title Compound ◽  
Charge Transfer Complex ◽  
Membered Ring ◽  
Asymmetric Unit ◽  
Centroid Distance ◽  
A Charge ◽  
Tcnq Molecule

The title compound, 2C14H12S·C12N4F4, was obtained by using 4,6-dimethyldibenzothiophene (DMDBT) as an electron donor and 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (F4TCNQ) as an electron acceptor. The asymmetric unit consists of one DMDBT molecule and one half of an F4TCNQ molecule, which lies on an inversion centre. In the crystal, the DMDBT and F4TCNQ molecules form a 2:1 unit via a charge-transfer interaction, with a centroid–centroid distance of 3.3681 (15) Å between the five-membered ring of DMDBT and the six-membered ring of F4TCNQ. An F...F contact [2.911 (1) Å] is also observed.

scholarly journals 9-Aminoacridin-10-ium 4-aminobenzoate dihydrate

2014 ◽  
Vol 70 (6) ◽  
pp. o657-o658 ◽  
Author(s):  
Nallathambi Dhanabalan ◽  
Kaliyaperumal Thanigaimani ◽  
Suhana Arshad ◽  
Ibrahim Abdul Razak ◽  
K. Joseph Santhanaraj
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Benzene Ring ◽  
Dihedral Angles ◽  
Water Molecules ◽  
Carboxylate Group ◽  
Asymmetric Unit ◽  
Axis Direction ◽  
Π Interactions ◽  
Hydrated Salt

The asymmetric unit of the title hydrated salt, C13H11N2+·C7H6NO2−·2H2O, consists of two independent 9-aminoacridinium cations, two 4-aminobenzoate anions and four water molecules. Both 9-aminoacridinium cations are essentially planar, with maximum deviations of 0.034 (1) and 0.025 (2) Å, and are protonated at the pyridine N atoms. The 4-aminobenzoate anions are approximately planar, with dihedral angles of 9.16 (19) and 5.4 (2)° between the benzene ring and the carboxylate group. In the crystal, the two independent anions are connected by N—H...O hydrogen bonds, forming a layer parallel to (100). The layers are connected through the cations by N—H...N and N—H...O hydrogen bonds. The water molecules, which form O—H...O hydrogen-bonded chains along theb-axis direction, connect the anions and the cations by O—H...O, N—H...O and C—H...O hydrogen bonds. The crystal structure also features π–π interactions [centroid–centroid distances = 3.6343 (9)–3.8366 (10) Å] and a C—H...π interaction.

Determination of Epsilon Aminocaproic Acid Based on Charge Transfer Complexation with p-Nitrophenlol by Spectrophotometry

2020 ◽  
Vol 16 ◽  
Author(s):  
Sheng-Yun Li ◽  
Fang Tian
Keyword(s):  
Charge Transfer ◽  
Aminocaproic Acid ◽  
Concentration Limit ◽  
Official Method ◽  
Good Precision ◽  
Pharmaceutical Dosage Forms ◽  
Relative Standard ◽  
A Charge ◽  
Epsilon Aminocaproic Acid

: A spectrophotometry was investigated for the determination of epsilon aminocaproic acid (EACA) with p-nitrophenol (PNP). The method was based on a charge transfer (CT) complexation of this drug as n-electron donor with π-acceptor PNP. Experiment indicated that the CT complexation was carried out at room temperature for 10 minutes in dimethyl sulfoxide solvent. The spectrum obtained for EACA/PNP system showed the maximum absorption band at wavelength of 425 nm. The stoichiometry of the CT complex was found to be 1:1 ratio by Job’s method between the donor and the acceptor. Different variables affecting the complexation were carefully studied and optimized. At the optimum reaction conditions, Beer’s law was obeyed in a concentration limit of 1～6 µg mL-1. The relative standard deviation was less than 2.9%. The apparent molar absoptivity was determined to be 1.86×104 L mol-1cm-1 at 425 nm. The CT complexation was also confirmed by both FTIR and 1H NMR measurements. The thermodynamic properties and reaction mechanism of the CT complexation have been discussed. The developed method could be applied successfully for the determination of the studied compound in its pharmaceutical dosage forms with a good precision and accuracy compared to official method as revealed by t- and F-tests.

The effect of partial methylation of the glycine amino group on crystal structure inN,N-dimethylglycine and its hemihydrate

2012 ◽  
Vol 68 (8) ◽  
pp. o283-o287 ◽  
Author(s):  
Vasily S. Minkov ◽  
Elena V. Boldyreva
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Water Molecules ◽  
Amino Group ◽  
Asymmetric Unit ◽  
Partial Methylation ◽  
Space Groups ◽  
Carboxylate Groups ◽  
Anhydrous Compound ◽  
Additional Hydrogen

N,N-Dimethylglycine, C4H9NO2, and its hemihydrate, C4H9NO2·0.5H2O, are discussed in order to follow the effect of the methylation of the glycine amino group (and thus its ability to form several hydrogen bonds) on crystal structure, in particular on the possibility of the formation of hydrogen-bonded `head-to-tail' chains, which are typical for the crystal structures of amino acids and essential for considering amino acid crystals as mimics of peptide chains. Both compounds crystallize in centrosymmetric space groups (PbcaandC2/c, respectively) and have twoN,N-dimethylglycine zwitterions in the asymmetric unit. In the anhydrous compound, there are no head-to-tail chains but the zwitterions formR44(20) ring motifs, which are not bonded to each other by any hydrogen bonds. In contrast, in the crystal structure ofN,N-dimethylglycinium hemihydrate, the zwitterions are linked to each other by N—H...O hydrogen bonds into infiniteC22(10) head-to-tail chains, while the water molecules outside the chains provide additional hydrogen bonds to the carboxylate groups.

scholarly journals Crystal structure of poly[diaquabis(μ5-benzene-1,3-dicarboxylato)(N,N-dimethylformamide)cadmium(II)disodium(I)]

2017 ◽  
Vol 73 (11) ◽  
pp. 1599-1602 ◽  
Author(s):  
Matimon Sangsawang ◽  
Kittipong Chainok ◽  
Nanthawat Wannarit
Keyword(s):  
Crystal Structure ◽  
Coordination Polymer ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Water Molecules ◽  
Asymmetric Unit ◽  
Carboxylate Groups ◽  
Benzene Rings ◽  
Coordinated Water ◽  
Coordinate Geometry

The title compound, [CdNa2(C8H4O4)2(C3H7NO)(H2O)2]nor [CdNa2(1,3-bdc)2(DMF)(H2O)2]n, is a new CdII–NaIheterobimetallic coordination polymer. The asymmetric unit consists of one CdIIatom, two NaIatoms, two 1,3-bdc ligands, two coordinated water molecules and one coordinated DMF molecule. The CdIIatom exhibits a seven-coordinate geometry, while the NaIatoms can be considered to be pentacoordinate. The metal ions and their symmetry-related equivalents are connectedviachelating–bridging carboxylate groups of the 1,3-bdc ligands to generate a three-dimensional framework. In the crystal, there are classical O—H...O hydrogen bonds involving the coordinated water molecules and the 1,3-bdc carboxylate groups and π–π stacking between the benzene rings of the 1,3-bdc ligands present within the frameworks.

scholarly journals Diosgenin hemihydrate

2012 ◽  
Vol 68 (8) ◽  
pp. o2357-o2357 ◽  
Author(s):  
María-Guadalupe Hernández Linares ◽  
Sylvain Bernès ◽  
Marcos Flores-Alamo ◽  
Gabriel Guerrero-Luna ◽  
Anselmo A. Martínez-Gallegos
Keyword(s):  
Crystal Structure ◽  
Water Molecule ◽  
Dimethyl Sulfoxide ◽  
Starting Material ◽  
Water Molecules ◽  
Asymmetric Unit ◽  
Acta Cryst ◽  
X Ray ◽  
Hydroxy Groups ◽  
Hydrogen Bonded

Diosgenin [or (22R,25R)-spirost-5-en-3β-ol] is the starting material of the Marker degradation, a cheap semi-synthesis of progesterone, which has been designated as an International Historic Chemical Landmark. Thus far, a single X-ray structure for diosgenin is known, namely its dimethyl sulfoxide solvate [Zhanget al.(2005).Acta Cryst.E61, o2324–o2325]. We have now determined the structure of the hemihydrate, C27H42O3·0.5H2O. The asymmetric unit contains two diosgenin molecules, with quite similar conformations, and one water molecule. Hydroxy groups in steroids and water molecules form O—H...O hydrogen-bondedR54(10) ring motifs. Fused edge-sharingR(10) rings form a backbone oriented along [100], which aggregates the diosgenin molecules in the crystal structure.

Sign in / Sign up

Export Citation Format

Share Document