scholarly journals Synthesis, Characterization, and Reaction Studies of Pd(II) Tripeptide Complexes

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5169
Author(s):  
Lindsey J. Monger ◽  
Dmitrii Razinkov ◽  
Ragnar Bjornsson ◽  
Sigridur G. Suman
Keyword(s):  
Ligand Exchange ◽  
Coordination Mode ◽  
Planar Geometry ◽  
Exchange Reactions ◽  
Aqueous Synthesis ◽  
Ph Values ◽  
Nmr Data ◽  
Square Planar ◽  
Acidic Conditions ◽  
Hydrolysis Of

The aqueous synthesis of Pd(II) complexes with alkylated tripeptides led to the hydrolysis of the peptides at low pH values and mixtures of complexed peptides were formed. A non-aqueous synthetic route allowed the formation and isolation of single products and their characterization. Pd(II) complexes with α-Asp(OR)AlaGly(OR), β-Asp(OR)AlaGly(OR), and TrpAlaGly(OR) (R = H or alkyl) as tri and tetradentate chelates were characterized. The tridentate coordination mode was accompanied by a fourth monodentate ligand that was shown to participate in both ligand exchange reactions and a direct removal to form the tetradentate coordination mode. The tetradentate coordination revealed a rare a hemi labile carbonyl goup coordination mode to Pd(II). Reactivity with small molecules such as ethylene, acids, formate, and episulfide was investigated. Under acidic conditions and in the presence of ethylene; acetaldehyde was formed. The Pd(II) is a soft Lewis acid and thiophilic and the complexes abstract sulfur from episulfide at apparent modest catalytic rates. The complexes adopt a square planar geometry according to a spectroscopic analysis and DFT calculations that were employed to evaluate the most energetically favorable coordination geometry and compared with the observed infrared and NMR data.

scholarly journals Tris(phosphan)-Nickel(0)-Ethen-Komplexe (dmpe)(PR3)Ni(C2H4). Molekülstruktur des (dmpe)(PØ3 )Ni(C2H4)/ Tris(phosphane)-nickel(0)-ethene Complexes (dmpe)(PR3)Ni(C2H4). Molecular Structure of (dmpe)(PO3)Ni(C2H4)

1984 ◽  
Vol 39 (8) ◽  
pp. 1076-1081 ◽  
Author(s):  
Klaus R. Pörschke ◽  
Richard Mynott ◽  
Carl Krüger ◽  
M. J. Romão
Keyword(s):  
Molecular Structure ◽  
Ligand Exchange ◽  
Crystal And Molecular Structure ◽  
Exchange Reactions ◽  
Tetrahedral Geometry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Nmr Data

AbstractSynthesis and properties of tris(phosphane)(ethene)nickel(0) complexes (dmpe)(PR3)Ni(C2H4) (R = CH3(4), c-C6H11(5), and C6H5 (6)) are reported. In solution. 4-6 are thermolabile and undergo ligand exchange reactions affording tetrakis(phosphane)nickel(0 ) and bis(phosphane)- (ethene)nickel(0) complexes. 1H, 13C, and 31P NMR data of 4-6 confirm the tetrahedral geometry around nickel. For 6 , the crystal and molecular structure has been determined by X-ray crystallography.

FACILE INTERMOLECULAR PHOSPHINE LIGAND EXCHANGE REACTIONS BETWEEN SQUARE PLANAR IRIDIUM AND PLATINUM CENTERS

1994 ◽  
Vol 31 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Robert L. Rominger ◽  
Jeffrey M. McFarland ◽  
James R. Jeitler ◽  
Jeffrey S. Thompson ◽  
Jim D. Atwood
Keyword(s):  
Ligand Exchange ◽  
Phosphine Ligand ◽  
Exchange Reactions ◽  
Square Planar

The Cycle Destruction during Complex Formation of 4-salicylideneamino-3-hydrazino-5-mercapto-1,2,4-triazole with Ni (II) ions

2020 ◽  
Vol 42 (5) ◽  
pp. 762-762
Author(s):  
Perizad A Fatullayeva Perizad A Fatullayeva ◽  
Ajdar A Medjidov Ajdar A Medjidov ◽  
Idayat M Mamedov Idayat M Mamedov ◽  
Pavel V Dorovatovskiy Pavel V Dorovatovskiy ◽  
Jan V Zubavichus Jan V Zubavichus ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Diffraction Method ◽  
Azomethine Nitrogen ◽  
Planar Geometry ◽  
X Ray Diffraction ◽  
Intermolecular Hydrogen Bonds ◽  
Phenolic Oxygen ◽  
Square Planar ◽  
Mechanism Of Hydrolysis ◽  
Hydrolysis Of

Using single crystal X-ray diffraction method, it was shown that the interaction of 4-salicylideneamino-3-hydrazino-5-mercapto-1,2,4-triazole with Ni (II) acetate yields a complex of nickel with salicylidene-thiosemicarbazone instead of the expected complex with the corresponding Schiff base. A possible mechanism of hydrolysis of the thiotriazole ring is proposed. The N- (salicylidene) thiosemicarbazone is a tridentate and almost flat structure ligand coordinates to the nickel (II) cation through thiosemicarbazone sulphur, phenolic oxygen, and azomethine nitrogen atoms. The nickel (II) ion in the complex is four-coordinated in distorted square-planar geometry. The intermolecular hydrogen bonds N─H∙∙∙N, as well as hydrogen bonds N─H∙∙∙O, O─H∙∙∙O and O─H∙∙∙S through the solvate water molecules, give rise to the 3-D network of the complex [Ni(TSC)((NH2)2CS)]•H2O.

New Platinum (II) Ternary Complexes of Formamidine and Pyrophosphate: Synthesis, Characterization and DFT Calculations and In vitro Cytotoxicity

2020 ◽  
Vol 23 (7) ◽  
pp. 611-623
Author(s):  
Ahmed A. Soliman ◽  
Fawzy A. Attaby ◽  
Othman I. Alajrawy ◽  
Azza A.A. Abou-hussein ◽  
Wolfgang Linert
Keyword(s):  
Cell Line ◽  
Cancer Cell ◽  
Theoretical Calculations ◽  
Thermal Analyses ◽  
Cancer Cell Line ◽  
Cellular Growth ◽  
Planar Geometry ◽  
Square Planar ◽  
Vis Spectroscopy

Aim and Objective: Platinum (II) and platinum (IV) of pyrophosphate complexes have been prepared and characterized to discover their potential as antitumor drugs. This study was conducted to prepare and characterize new ternary platinum (II) complexes with formamidine and pyrophosphate as an antitumor candidate. Materials and Methods: The complexes have been characterized by mass, infrared, UV-Vis. spectroscopy, elemental analysis, magnetic susceptibility, thermal analyses, and theoretical calculations. They have been tested for their cytotoxicity, which was carried out using the fastcolorimetric assay for cellular growth and survival against MCF-7 (breast cancer cell line), HCT- 116 (colon carcinoma cell line), and HepG-2 (hepatocellular cancer cell line). Results: All complexes are diamagnetic, and the electronic spectral data displayed the bands due to square planar Pt(II) complexes. The optimized complexes structures (1-4) indicated a distorted square planar geometry where O-Pt-O and N-Pt-N bond angles were 82.04°-96.44°, respectively. Conclusion: The complexes showed noticeable cytotoxicity and are considered as promising antitumor candidates for further applications.

Voltammetric Studies of Some Novel Fe(III) Complexes with Quadridentate Ligands. The Axial Ligand-Exchange Reactions in DMF and DMSO

1995 ◽  
Vol 60 (7) ◽  
pp. 1140-1157 ◽  
Author(s):  
Ljiljana S. Jovanovic ◽  
Luka J. Bjelica
Keyword(s):  
Oxidation State ◽  
Chemical Reactions ◽  
Ligand Exchange ◽  
Kinetic Data ◽  
Central Atom ◽  
Axial Ligand ◽  
Exchange Reactions ◽  
Ligand Effect ◽  
Condensation Products ◽  
Voltammetric Studies

The electrochemistry of four novel Fe(III) complexes of the type [Fe(L)Cl], involving quadridentate ligands based on the condensation products of benzoylacetone-S-methylisothiosemicarbazone with salicylaldehyde, 5-chlorosalicylaldehyde, 3,5-dichlorosalicylaldehyde or 5-nitrosalicylaldehyde, was studied in DMF and DMSO at a GC electrode. All complexes undergo a two-step one-electron reductions, usually complicated by chemical reactions. In solutions containing Cl-, the ligand-exchange reactions Cl--DMF and Cl--DMSO take place. Stability of the chloride-containing complexes was discussed in terms of the coordinated ligand effect, oxidation state of the central atom and, in particular, of the donor effect of the solvent. Some relevant kinetic data were calculated.

Preparation of Organized Mesoporous Silica from Sodium Metasilicate Solutions in Alkaline Medium Using Nonionic Surfactants

2003 ◽  
Vol 68 (10) ◽  
pp. 2019-2031 ◽  
Author(s):  
Markéta Zukalová ◽  
Jiří Rathouský ◽  
Arnošt Zukal
Keyword(s):  
Mesoporous Silica ◽  
Ethylene Oxide ◽  
Sodium Metasilicate ◽  
Spherical Particles ◽  
Structure Directing Agent ◽  
Inorganic Species ◽  
Poly Ethylene Oxide ◽  
Acidic Conditions ◽  
Poly Ethylene ◽  
Hydrolysis Of

A new procedure has been developed, which is based on homogeneous precipitation of organized mesoporous silica from an aqueous solution of sodium metasilicate and a nonionic poly(ethylene oxide) surfactant serving as a structure-directing agent. The decrease in pH, which induces the polycondensation of silica, is achieved by hydrolysis of ethyl acetate. Owing to the complexation of Na+ cations by poly(ethylene oxide) segments, assembling of the mesostructure appears to occur under electrostatic control by the S0Na+I- pathway, where S0 and I- are surfactant and inorganic species, respectively. As the complexation of Na+ cations causes extended conformation of poly(ethylene oxide) segments, the pore size and pore volume of organized mesoporous silica increase in comparison with materials prepared under neutral or acidic conditions. The assembling of particles can be fully separated from their solidification, which results in the formation of highly regular spherical particles of mesoporous silica.

scholarly journals The Hsp60 Protein of Helicobacter Pylori Exhibits Chaperone and ATPase Activities at Elevated Temperatures

BioChem ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 19-25
Author(s):  
Jose A. Mendoza ◽  
Julian L. Ignacio ◽  
Christopher M. Buckley
Keyword(s):  
Helicobacter Pylori ◽  
Heat Stress ◽  
Molecular Chaperone ◽  
Elevated Temperatures ◽  
Citrate Synthase ◽  
Gastric Epithelium ◽  
Acidic Conditions ◽  
H Pylori ◽  
Induced Aggregation ◽  
Hydrolysis Of

The heat-shock protein, Hsp60, is one of the most abundant proteins in Helicobacter pylori. Given its sequence homology to the Escherichia coli Hsp60 or GroEL, Hsp60 from H. pylori would be expected to function as a molecular chaperone in this organism. H. pylori is a type of bacteria that grows on the gastric epithelium, where the pH can fluctuate between neutral and 4.5, and the intracellular pH can be as low as 5.0. We previously showed that Hsp60 functions as a chaperone under acidic conditions. However, no reports have been made on the ability of Hsp60 to function as a molecular chaperone under other stressful conditions, such as heat stress or elevated temperatures. We report here that Hsp60 could suppress the heat-induced aggregation of the enzymes rhodanese, malate dehydrogenase, citrate synthase, and lactate dehydrogenase. Moreover, Hsp60 was found to have a potassium and magnesium-dependent ATPase activity that was stimulated at elevated temperatures. Although, Hsp60 was found to bind GTP, the hydrolysis of this nucleotide could not be observed. Our results show that Hsp60 from H. pylori can function as a molecular chaperone under conditions of heat stress.

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