scholarly journals Novel H-Bonded Synthons in Copper Supramolecular Frameworks with Aminoethylpiperazine-Based Ligands. Synthesis, Structure and Catalytic Activity

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5435
Author(s):  
Oksana V. Nesterova ◽  
Armando J. L. Pombeiro ◽  
Dmytro S. Nesterov
Keyword(s):  
Reaction Mechanisms ◽  
Active Catalyst ◽  
Single Point ◽  
Organic Ligand ◽  
Schiff Base Complexes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Butyl Peroxide ◽  
Supramolecular Networks

New Schiff base complexes [Cu2(HL1)(L1)(N3)3]∙2H2O (1) and [Cu2L2(N3)2]∙H2O (2) were synthesized. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction analysis. The HL1 ligand results from the condensation of salicylaldehyde and 1-(2-aminoethyl)piperazine, while a new organic ligand, H2L2, was formed by the dimerization of HL1 via a coupling of two piperazine rings of HL1 on a carbon atom coming from DMF solvent. The dinuclear building units in 1 and 2 are linked into complex supramolecular networks through hydrogen and coordination bondings, resulting in 2D and 1D architectures, respectively. Single-point and broken-symmetry DFT calculations disclosed negligible singlet–triplet splittings within the dinuclear copper fragments in 1 and 2. Catalytic studies showed a remarkable activity of 1 and 2 towards cyclohexane oxidation with H2O2 in the presence of nitric acid and pyridine as promoters and under mild conditions (yield of products up to 21%). Coordination compound 1 also acts as an active catalyst in the intermolecular coupling of cyclohexane with benzamide using di-tert-butyl peroxide (tBuOOtBu) as a terminal oxidant. Conversion of benzamide at 55% was observed after 24 h reaction time. By-product patterns and plausible reaction mechanisms are discussed.

An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

1991 ◽  
Vol 56 (12) ◽  
pp. 2917-2935 ◽  
Author(s):  
Eva Klinotová ◽  
Václav Křeček ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Spectral Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Condensation Products ◽  
Unsaturated Lactones ◽  
C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

scholarly journals Spatially Resolved Forming Mechanisms Detection in Single Point Incremental Forming Using Synchrotron Based Texture Analysis

2021 ◽  
Author(s):  
Mateus Dobecki ◽  
Alexander Poeche ◽  
Walter Reimers
Keyword(s):  
Texture Analysis ◽  
Incremental Forming ◽  
Single Point ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Forming Mechanism ◽  
Spatially Resolved ◽  
Step Down ◽  
Stress States

AbstractDespite the ongoing success of understanding the deformation states in sheets manufactured by single-point incremental forming (SPIF), the unawareness of the spatially resolved influence of the forming mechanisms on the residual stress states of incrementally formed sheet metal parts impedes their application-optimized use. In this study, a well-founded experimental proof of the occurring forming mechanisms shear, bending and stretching is presented using spatially resolved, high-energy synchrotron x-ray diffraction-based texture analysis in transmission mode. The measuring method allows even near-surface areas to be examined without any impairment of microstructural influences due to tribological reactions. The depth-resolved texture evolution for different sets of forming parameters offers insights into the forming mechanisms acting in SPIF. Therefore, the forming mechanisms are triggered explicitly by adjusting the vertical step-down increment Δz for groove, plate and truncated cone geometries. The texture analysis reveals that the process parameters and the specimen geometries used lead to characteristic changes in the crystallites’ orientation distribution in the formed parts due to plastic deformation. These forming-induced reorientations of the crystallites could be assigned to the forming mechanisms by means of defined reference states. It was found that for groove, plate and truncated cone geometries, a decreasing magnitude of step-down increments leads to a more pronounced shear deformation, which causes an increasing work hardening especially at the tool contact area of the formed parts. Larger step-down increments, on the other hand, induce a greater bending deformation. The plastic deformation by bending leads to a complex stress field that involves alternating residual tensile stresses on the tool and residual compressive stresses on the tool-averted side incrementally formed sheets. The present study demonstrates the potential of high-energy synchrotron x-ray diffraction for the spatially resolved forming mechanism research in SPIF. Controlling the residual stress states by optimizing the process parameters necessitates knowledge of the fundamental forming mechanism action.

A New Organic-Inorganic Hybrid Based on L-Arginine and Polyoxoanion

2015 ◽  
Vol 1105 ◽  
pp. 335-338
Author(s):  
Qiong Wu ◽  
Jing Lu ◽  
Xiao Lin Ji ◽  
Tao Yu Zou ◽  
Zhen Fang Qiao ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Sodium Cation ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Inorganic Hybrid ◽  
X Ray ◽  
Hydrogen Bonding Interactions ◽  
Photocatalytic Activities ◽  
Metal Organic ◽  
Supramolecular Networks

Modifying polyoxometalates with organic and/or metal-organic moieties is a widely adopted method for broading the range of properties. In this work a new polyoxometalate constructed from Anderson-type polyoxoanions and L-arginine (Arg =L-arginine) molecules Na [CrMo6(OH)6O18]}(H2Arg)2·8H2O(1) has been synthesized via conventional method and characterized by routine techniques. Single-crystal X-Ray diffraction analysis shows that compound 1 is constructed by chiralL-arginine grafted Anderson-type clusters, sodium cation and water molecules which are further stabilized by hydrogen bonding interactions constitute 3D supramolecular networks. In addition, both antitumor behavior and photocatalytic activities of compound 1 were investigated.

scholarly journals Human insulin polymorphism upon ligand binding and pH variation: the case of 4-ethylresorcinol

IUCrJ ◽  
2015 ◽  
Vol 2 (5) ◽  
pp. 534-544 ◽  
Author(s):  
S. Fili ◽  
A. Valmas ◽  
M. Norrman ◽  
G. Schluckebier ◽  
D. Beckers ◽  
...  
Keyword(s):  
Human Insulin ◽  
Organic Ligand ◽  
European Synchrotron Radiation Facility ◽  
X Ray Diffraction ◽  
Ph Variation ◽  
X Ray ◽  
X Ray Crystallography ◽  
Swiss Light Source ◽  
Crystallization Experiments ◽  
Ph Range

This study focuses on the effects of the organic ligand 4-ethylresorcinol on the crystal structure of human insulin using powder X-ray crystallography. For this purpose, systematic crystallization experiments have been conducted in the presence of the organic ligand and zinc ions within the pH range 4.50–8.20, while observing crystallization behaviour around the isoelectric point of insulin. High-throughput crystal screening was performed using a laboratory X-ray diffraction system. The most representative samples were selected for synchrotron X-ray diffraction measurements, which took place at the European Synchrotron Radiation Facility (ESRF) and the Swiss Light Source (SLS). Four different crystalline polymorphs have been identified. Among these, two new phases with monoclinic symmetry have been found, which are targets for the future development of microcrystalline insulin drugs.

Metal-Controlled Assembly Tuning Coordination Polymers with Flexible 2-(1H-imidazole-1-yl)acetic Acid (Hima)

2006 ◽  
Vol 59 (9) ◽  
pp. 647 ◽  
Author(s):  
Yong-Tao Wang ◽  
Gui-Mei Tang ◽  
Da-Wei Qin
Keyword(s):  
Coordination Polymers ◽  
Weak Interactions ◽  
Critical Role ◽  
Three Dimensional ◽  
Supramolecular Network ◽  
Water Medium ◽  
New Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Supramolecular Networks

Three new inorganic–organic coordination polymers based on a versatile linking unit 2-(1H-imidazole-1-yl)acetate (Hima) and divalent Mn(ii), Ni(ii), and Cu(ii) ions, exhibiting two kinds of two dimensionalities with different topological structures, have been prepared in water medium and structurally characterized by single-crystal X-ray diffraction analysis. Reaction of MnCl2·4H2O and Ni(NO3)2·6H2O with Hima yielded neutral two-dimensional (2D) coordination polymers [M(ima)2]n, M = Mn(ii) 1, and Ni(ii) 2 with isostructural 2D coordination polymers possessing (3,6) topology structures, which further stack into three-dimensional (3D) supramolecular networks through C–H···O weak interactions. However, when Cu(NO3)2·4H2O was used, a neutral 2D coordination polymer [Cu(ima)2]n 3 consisting of rhombus units was generated, which showed a 3D supramolecular network through C–H···O weak interactions. Among these polymers, the building block ima anion exhibits different coordination modes. These results indicate that the versatile nature of this flexible ligand, together with the coordination preferences of the metal ions, plays a critical role in construction of these novel coordination polymers. Spectral and thermal properties of these new materials have also been investigated.

Carboxyl graphene reinforced melamine-based polyamide nanocomposites

2021 ◽  
pp. 089270572110514
Author(s):  
Himanshu V Madhad ◽  
Dilip V Vasava
Keyword(s):  
Electron Microscopy ◽  
Decomposition Temperature ◽  
Differential Scanning Calorimetric ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
Mild Conditions ◽  
Thermal Stability Of ◽  
Infrared Techniques ◽  
Scanning Electron

Over the years, various types of techniques have been used for the synthesis of nanocomposites. In this work, melamine-based polyamide (PA) was synthesized using a one-pot polycondensation method under mild conditions. carboxyl graphene (CG)/PA nanocomposites (CGMPA) were prepared by CG nanofiller loadings of 1, 3, and 5 wt.% via delamination/adsorption approach. The prepared CGMPA nanocomposites were characterized using different analyses, such as Fourier transform infrared techniques (FTIR), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), differential scanning calorimetric (DSC), and thermogravimetric analysis (TGA). The effects of the CG on the thermal properties of the CGMPA nanocomposites were significant. The results showed that the melting temperature (Tm) of neat PA and CGMPA were increased from 378°C to 393°C suggested better dispersion of CG in PA matrix. The decomposition temperature of PA was increased from 451°C to 463°C in CGMPA nanocomposites indicates the better thermal stability of PA matrix by addition of CG.

Supramolecular networks of Mn(III)–Schiff base complexes assembled by nitrate counterions: X-ray crystal structures of 1D chains and 2D networks

Polyhedron ◽  
2012 ◽  
Vol 31 (1) ◽  
pp. 379-385 ◽  
Author(s):  
M. Ángeles Vázquez-Fernández ◽  
M. Isabel Fernández-García ◽  
Ana M. González-Noya ◽  
Marcelino Maneiro ◽  
Manuel R. Bermejo ◽  
...  
Keyword(s):  
Schiff Base ◽  
Crystal Structures ◽  
Schiff Base Complexes ◽  
X Ray ◽  
Supramolecular Networks ◽  
1D Chains

scholarly journals Tetranuclear Cu(ii)-chiral complexes: synthesis, characterization and biological activity

RSC Advances ◽  
2019 ◽  
Vol 9 (42) ◽  
pp. 24087-24091 ◽  
Author(s):  
Krisana Peewasan ◽  
Marcel P. Merkel ◽  
Kristof Zarschler ◽  
Holger Stephan ◽  
Christopher E. Anson ◽  
...  
Keyword(s):  
Biological Activity ◽  
Schiff Base ◽  
Single Crystal ◽  
Cd Spectroscopy ◽  
Schiff Base Complexes ◽  
X Ray Diffraction ◽  
Chiral Complexes ◽  
Enantiomerically Pure ◽  
X Ray

A pair of tetranuclear chiral Cu(ii)-Schiff-base complexes were synthesized using enantiomerically pure (S)-H2L and (R)-H2L ligands. These were characterised using single-crystal X-ray diffraction and CD spectroscopy and their biological activity tested.

Anti-mycobacterial activities of copper(II) salicylaldimine complexes derived from long-chain aliphatic amines

2013 ◽  
Vol 91 (11) ◽  
pp. 1093-1097 ◽  
Author(s):  
Alyssa E. Patterson ◽  
Eric G. Bowes ◽  
Allyson Bos ◽  
Taryn O’Neill ◽  
Haoxin Li ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Schiff Base ◽  
Aliphatic Amines ◽  
Schiff Base Complexes ◽  
Aliphatic Chain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Assisted ◽  
Long Chain

Twelve copper(II) Schiff base complexes derived from lipophilic amines have been prepared using either salicylaldehyde or ortho-vanillin via a microwave-assisted reaction. All complexes have been obtained elementally pure and an X-ray diffraction of an isopentyl derivative has confirmed the structure of these compounds. All complexes showed a promising degree of anti-mycobacterial activity against Mycobacterium tuberculosis, where activity seemed to increase with an increase in the length of the aliphatic chain.

Synthesis, Characterization, and Antimicrobial Activities of New Organic-Inorganic Hybird Compound Based on Polyoxovanadate and Metal-Schiff-Base Complex

2015 ◽  
Vol 1105 ◽  
pp. 215-219
Author(s):  
Qiong Wu ◽  
Xiao Lin Ji ◽  
Lu Jing ◽  
Hong Ping Ju ◽  
Hai Wang
Keyword(s):  
Schiff Base ◽  
Human Cancer ◽  
Synergetic Effect ◽  
Schiff Base Complex ◽  
Antimicrobial Activities ◽  
Schiff Base Complexes ◽  
X Ray Diffraction ◽  
Base Complex ◽  
X Ray ◽  
Vis Spectroscopy

The reaction of polyoxovanadate and metal-Schiff base complex resulted in the formation of a new organic-inorganic hybrid compounds with the formula Na2[Mn (Salen)(H2O)2]4[V10O28]·9H2O (1) (salen=N,N’-ethylene-bis (salicylideneiminate). Compound 1 have been structurally characterized by IR, UV-vis spectroscopy and single crystal X-ray diffraction. Crystal data for 1: Triclinic, P-1, a=14.1123(3)Å, b=13.9397(7) Å, c=14.2564(5)Å, α=65.4160(9)°, β=81.3920(6)°, γ=89.5740(7) °. Structural analyses revealed that compound 1 represent a rare example of isopolyoxovanadate based metal-Schiff-base complexes, moreover, this is the first POM based metal Schiff-base complex isolated in aqueous solution medium, which may also propose a green chemical way to the synthesis of POM based hybrid. Compare with isopolyoxovanadate precusor Na6 [V10O28], compound 1 exhibit higher antimicrobial activities against human cancer cell, the phenomenon can be explained by the synergetic effect between POM and Schiff-base complex.

Sign in / Sign up

Export Citation Format

Share Document