scholarly journals Expanding the Family of Octahedral Chiral-at-Metal Cobalt(III) Catalysts by Introducing Tertiary Amine Moiety into the Ligand

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 152
Author(s):  
Tat’yana F. Savel’yeva ◽  
Olga V. Khromova ◽  
Vladimir A. Larionov ◽  
Alexander F. Smol’yakov ◽  
Ivan V. Fedyanin ◽  
...  
Keyword(s):  
Molecular Electrostatic Potential ◽  
Bifunctional Catalyst ◽  
Cd Spectroscopy ◽  
Catalyst Design ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
Hydrogen Bond Donor ◽  
Catalytic Potential ◽  
The Family ◽  
Brønsted Base

Chiral metal-templated complexes are attractive catalysts for organic synthetic transformations. Herein, we introduce a novel chiral cobalt(III)-templated complex based on chiral trans-3,4-diamino-1-benzylpyrrolidine and 3,5-di-tert-butyl-salicylaldehyde which features both hydrogen bond donor and Brønsted base functionalities. The obtained complexes were fully characterized by 1H, 13C NMR, IR-, UV-vis, CD-spectroscopy and by a single X-ray diffraction analysis. It was shown that chlorine anion is connected with amino groups of the complex via a hydrogen bonding. DFT calculations of charges and molecular electrostatic potential of the cobalt(III) complex showed that the basicity of the complex is certainly diminished as compared with the routine tertiary amines but the acidity of the conjugated acid of the complex should be increased. Thus, the catalytic potential of the complex may be much greater as a chiral acid than a chiral base. We believe that this work opens a new way in chiral bifunctional catalyst design.

Axially Chiral Bis(α-amino Acid)s and Their Deamino Analogues. Synthesis and Configurational Assignment

1998 ◽  
Vol 63 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Miloš Tichý ◽  
Luděk Ridvan ◽  
Miloš Buděšínský ◽  
Jiří Závada ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nmr Spectra ◽  
Building Blocks ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
X Ray ◽  
Configurational Assignment ◽  
Symmetry Properties ◽  
Axially Chiral ◽  
Polymeric Structures

The axially chiral bis(α-amino acid)s cis-2 and trans-2 as possible building blocks for polymeric structures of novel type of helicity were prepared. Their configuration has been determined by NMR spectroscopy and, in the case of the trans-isomer, confirmed by single-crystal X-ray diffraction. Analogous pair of stereoisomeric diacids cis-3 and trans-3, devoid of the amino groups, was also prepared and their configuration assigned. The observed differences in the NMR spectra of cis- and trans-isomers of 2 and 3 are discussed from the viewpoint of their different symmetry properties.

scholarly journals Crystal Chemical Relations in the Shchurovskyite Family: Synthesis and Crystal Structures of K2Cu[Cu3O]2(PO4)4 and K2.35Cu0.825[Cu3O]2(PO4)4

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 807
Author(s):  
Ilya V. Kornyakov ◽  
Sergey V. Krivovichev
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structural Complexity ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Complexity Measures ◽  
X Ray ◽  
The Family ◽  
Similarities And Differences ◽  
Related Compounds

Single crystals of two novel shchurovskyite-related compounds, K2Cu[Cu3O]2(PO4)4 (1) and K2.35Cu0.825[Cu3O]2(PO4)4 (2), were synthesized by crystallization from gaseous phase and structurally characterized using single-crystal X-ray diffraction analysis. The crystal structures of both compounds are based upon similar Cu-based layers, formed by rods of the [O2Cu6] dimers of oxocentered (OCu4) tetrahedra. The topologies of the layers show both similarities and differences from the shchurovskyite-type layers. The layers are connected in different fashions via additional Cu atoms located in the interlayer, in contrast to shchurovskyite, where the layers are linked by Ca2+ cations. The structures of the shchurovskyite family are characterized using information-based structural complexity measures, which demonstrate that the crystal structure of 1 is the simplest one, whereas that of 2 is the most complex in the family.

Alkaloids of Rauvolfia salicifolia GRISEB species

1982 ◽  
Vol 47 (11) ◽  
pp. 2912-2921 ◽  
Author(s):  
Patricia Sierra ◽  
Ladislav Novotný ◽  
Zdeněk Samek ◽  
Miloš Buděšínský ◽  
Ladislav Dolejš ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Cd Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute

From the endemic Cuban species Rauvolfia salicifolia GRISEB nine alkaloids were isolated of which the following seven had been already described: (+)-ajmalidine (I), (-)-reserpiline (II), (-)-isoreserpiline (III), (-)-isocarapanaubine (IV), (-)-ajmalicine (V), (+)-vellosimine (VI), and (+)-yohimbine (VII). The structure of (-)-raucubaine (VIII) had been previously determined by X-ray diffraction and the structure of the alkaloid (-)-raucubainine (IX) was suggested on the basis of its conversion to (-)-raucubaine (VIII). The absolute configuration of (-)-raucubaine and (-)-raucubainine was elucidated by CD spectroscopy.

Studies Directed Towards the Total Synthesis of Anticapsin and Related Compounds. IV. Competitive Reaction of Amino and Carboxy Substituents in the Halohydrination of 2-Aminobicyclo[2.2.2]oct-5-ene-2-carboxylic Acid Derivatives

1994 ◽  
Vol 47 (12) ◽  
pp. 2221 ◽  
Author(s):  
MJ Crossley ◽  
SR Davies ◽  
TW Hambley
Keyword(s):  
Total Synthesis ◽  
The Other ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
Competitive Reaction ◽  
Trimethylsilyl Group ◽  
X Ray ◽  
Tricyclic Compounds ◽  
Tricyclic Compound ◽  
Related Compounds

Bromohydrination of benzyl (1RS,2SR,4SR)-2-benzyloxycarbonylamino-1-trimethylsilyloxy-bicyclo[2.2.2]oct-5-ene-2-carboxylate (6a) and the (1RS,2RS,4SR)- diastereomer (6b) with N- bromoacetamide in aqueous dioxan has been investigated. These reactions are highly regio-and stereo-selective and give the corresponding bromohydrins (9a) and (9b), but in moderate to low yield. These bromohydrins have the necessary stereochemistry for conversion into anticapsin. The other products from the reaction are tricyclic compounds formed by capture of the anti- bromonium cation intermediates or resultant bromohydrins by interaction with the proximal protected carboxy and amino groups within the molecules. Thus the carbolactone (11) is formed from the endo -adduct (6a), and the carbonimidic acid derivative (12) and the cyclic urethane (13) are formed from the exo-adduct (6b). Cleavage of the trimethylsilyl group from the tricyclic compound (12) gives benzyl (1RS,2RS,3RS,7RS,8RS)-5-benzyloxy-2-bromo-8-hydroxy-4-oxa-6-azatricyclo[5.3.1.03,8]undec-5-ene-7-carboxylate(14), the structure of which was determined by X-ray diffraction methods and refined to a residual of 0.035 for 1549 independent observed reflections. The crystals of (14) are monoclinic, P21/c, a 12.954(3), b 6.197(3), c 26.784(7) Ǻ, β 95.33(2)°, Z 4. Reactions attempting to generate iodohydrins from the alkenes (6) were also highly regioselective and gave detrimethylsilylated iodo analogues of (11) and (13).

Structure Refinements of the Layered Intergrowth Phases SbIIISbV x A 1−x TiO6 (x≃0, A = Ta, Nb) Using Synchrotron X-ray Powder Diffraction Data

1997 ◽  
Vol 53 (6) ◽  
pp. 861-869 ◽  
Author(s):  
C. D. Ling ◽  
J. G. Thompson ◽  
S. Schmid ◽  
D. J. Cookson ◽  
R. L. Withers
Keyword(s):  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Homologous Series ◽  
Rietveld Method ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
X Ray ◽  
The Family

The structures of the layered intergrowth phases SbIIISb^{\rm V}_xAl-xTiO6 (x \simeq 0, A = Ta, Nb) have been refined by the Rietveld method, using X-ray diffraction data obtained using a synchrotron source. The starting models for these structures were derived from those of Sb^{\rm III}_3Sb^{\rm V}_xA 3−xTiO14 (x = 1.26, A = Ta and x = 0.89, A = Nb), previously solved by single-crystal X-ray diffraction. There were no significant differences between the derived models and the final structures, validating the approach used to obtain the models and confirming that the n = 1 and n = 3 members of the family, Sb^{\rm III}_nSb^{\rm V}_xA n−xTiO4n+2 are part of a structurally homologous series.

A first Mn member in the struvite morphotropic series, CsMn(H2O)6(PO4): hydrothermal synthesis, crystal structure and interconnections within the family of related phosphates

2018 ◽  
Vol 74 (8) ◽  
pp. 936-943
Author(s):  
Galina V. Kiriukhina ◽  
Olga V. Yakubovich ◽  
Ekaterina M. Kochetkova ◽  
Olga V. Dimitrova ◽  
Anatoliy S. Volkov
Keyword(s):  
Crystal Structure ◽  
Ionic Radius ◽  
The Novel ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
Hydrothermal Conditions ◽  
X Ray ◽  
Cell Parameters ◽  
Structural Relationships ◽  
The Family

Caesium manganese hexahydrate phosphate, CsMn(H2O)6(PO4), was synthesized under hydrothermal conditions. Its crystal structure was determined from single-crystal X-ray diffraction data. The novel phase crystallizes in the hexagonal space group P63 mc and represents the first manganese member in the struvite morphotropic series, AM(H2O)6(TO4). Its crystal structure is built from Mn(H2O)6 octahedra and PO4 tetrahedra linked into a framework via hydrogen bonding. The large Cs atoms are encapsulated in the framework cuboctahedral cavities. It is shown that the size of the A + ionic radius within the morphotropic series AM(H2O)6(XO4) results is certain types of crystal structures and affects the values of the unit-cell parameters. Structural relationships with Na(H2O)Mg(H2O)6(PO4) and the mineral hazenite, KNa(H2O)2Mg2(H2O)12(PO4)2, are discussed.

scholarly journals Nanosheets of CuCo2O4 As a High-Performance Electrocatalyst in Urea Oxidation

2019 ◽  
Vol 9 (4) ◽  
pp. 793 ◽  
Author(s):  
Camila Zequine ◽  
Fangzhou Wang ◽  
Xianglin Li ◽  
Deepa Guragain ◽  
S.R. Mishra ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Nickel Foam ◽  
Low Cost ◽  
Agricultural Waste ◽  
Bifunctional Catalyst ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electroactive Material

The urea oxidation reaction (UOR) is a possible solution to solve the world’s energy crisis. Fuel cells have been used in the UOR to generate hydrogen with a lower potential compared to water splitting, decreasing the costs of energy production. Urea is abundantly present in agricultural waste and in industrial and human wastewater. Besides generating hydrogen, this reaction provides a pathway to eliminate urea, which is a hazard in the environment and to people’s health. In this study, nanosheets of CuCo2O4 grown on nickel foam were synthesized as an electrocatalyst for urea oxidation to generate hydrogen as a green fuel. The synthesized electrocatalyst was characterized using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electroactivity of CuCo2O4 towards the oxidation of urea in alkaline solution was evaluated using electrochemical measurements. Nanosheets of CuCo2O4 grown on nickel foam required the potential of 1.36 V in 1 M KOH with 0.33 M urea to deliver a current density of 10 mA/cm2. The CuCo2O4 electrode was electrochemically stable for over 15 h of continuous measurements. The high catalytic activities for the hydrogen evolution reaction make the CuCo2O4 electrode a bifunctional catalyst and a promising electroactive material for hydrogen production. The two-electrode electrolyzer demanded a potential of 1.45 V, which was 260 mV less than that for the urea-free counterpart. Our study suggests that the CuCo2O4 electrode can be a promising material as an efficient UOR catalyst for fuel cells to generate hydrogen at a low cost.

scholarly journals Temperature-programmed surface reactions of methanol and dimethyl ether on bifunctional catalysts for the direct synthesis of dimethyl ether from syngas

2018 ◽  
Vol 243 ◽  
pp. 00002
Author(s):  
Olga Vodorezova ◽  
Pavel Musich ◽  
Natalia Karakchieva ◽  
Lothar Heinrich ◽  
Irina Kurzina
Keyword(s):  
Dimethyl Ether ◽  
Direct Synthesis ◽  
Bifunctional Catalyst ◽  
Bifunctional Catalysts ◽  
X Ray Diffraction ◽  
X Ray ◽  
Physical Mixing ◽  
Stage Synthesis ◽  
Temperature Programmed ◽  
Synthesis Of Dimethyl Ether

Dimethyl ether (DME) can be used as a replacement for diesel fuel in transportation. The catalytic effectiveness of bifunctional catalysts for DME one-stage synthesis from carbon monoxide and hydrogen was estimated in the paper. Bifunctional catalysts CuZnAl/HZSM-5, CuZnAlCr/HZSM-5, and CuZnAlZr/HZSM-5 were obtained by physical mixing of CuZnAl(Cr/Zr)– Ох and HZSM-5 components and were characterized by BET, X-ray diffraction, and temperatureprogrammed surface reaction methods. Based on the TPSR results, the mechanism of the interaction of methanol and DME with the surface of the bifunctional catalyst was studied. It was found that the temperature range of the greatest catalytic activity was 240–260 °С.

scholarly journals DFT-Assisted Design and Evaluation of Bifunctional Amine/Pyridine-Oxazoline Metal Catalysts for Additions of Ketones to Unactivated Alkenes and Alkynes

Synthesis ◽  
2018 ◽  
Vol 51 (02) ◽  
pp. 450-462 ◽  
Author(s):  
Chris Dockendorff ◽  
Eric Greve ◽  
Jacob Porter
Keyword(s):  
Density Functional ◽  
Bond Formation ◽  
Bifunctional Catalyst ◽  
Catalyst Design ◽  
Epoxide Ring ◽  
Nmr Studies ◽  
Acidic Group ◽  
Direct Addition ◽  
Group 10 ◽  
Group 10 Metals

Bifunctional catalyst systems for the direct addition of ­ketones to unactivated alkenes/alkynes were designed and modeled by density functional theory (DFT). The designed catalysts possess bidentate ligands suitable for binding of pi-acidic group 10 metals capable of activating alkenes/alkynes, and a tethered organocatalyst amine to ­activate the ketone via formation of a nucleophilic enamine intermediate. The structures of the designed catalysts before and after C–C bond formation were optimized using DFT, and reaction steps involving group 10 metals were predicted to be significantly exergonic. A novel oxazoline precatalyst with a tethered amine separated by a meta-substituted benzene spacer was synthesized via a 10-step sequence that ­includes a key regioselective epoxide ring-opening step. It was combined with group 10 metal salts, including cationic Pd(II) and Pt(II), and screened for the direct addition of ketones to several alkenes and an ­internal alkyne. 1H NMR studies suggest that catalyst-catalyst inter­actions with this system via amine–metal coordination may preclude the desired addition reactions. The catalyst design approach disclosed here, and the promising calculations obtained with square planar group 10 metals, light a path for the discovery of novel bifunctional catalysts for C–C bond formation.

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