Chromium ethylene polymerisation catalysts bearing reduced Schiff-base N,O-chelate ligands

1999 ◽  
pp. 827-830 ◽  
Author(s):  
Vernon C. Gibson ◽  
Claire Newton ◽  
Carl Redshaw ◽  
Gregory A. Solan ◽  
Andrew J. P. White ◽  
...  
Keyword(s):  
Schiff Base ◽  
Reduced Schiff Base ◽  
Chelate Ligands ◽  
Ethylene Polymerisation

Insight into the formation of H-bonds propagating the monomeric zinc complexes of a tridentate reduced Schiff base to form an infinite chain

CrystEngComm ◽  
2021 ◽  
Author(s):  
Mainak Karmakar ◽  
Antonio Frontera ◽  
Shouvik Chattopadhyay
Keyword(s):  
Schiff Base ◽  
Solid State ◽  
Dft Calculations ◽  
Zinc Complexes ◽  
Infinite Chain ◽  
State Structure ◽  
Computational Tools ◽  
Solid State Structure ◽  
Reduced Schiff Base ◽  
Insight Into

The formation of an infinite 1D assembly is governed by the H-bonding interactions in the solid state structure of the two zinc complexes. It has been analyzed energetically using DFT calculations and several computational tools.

scholarly journals Ni(II) Dimers of NNO Donor Tridentate Reduced Schiff Base Ligands as Alkali Metal Ion Capturing Agents: Syntheses, Crystal Structures and Magnetic Properties

2018 ◽  
Vol 4 (4) ◽  
pp. 51 ◽  
Author(s):  
Monotosh Mondal ◽  
Maharudra Chakraborty ◽  
Michael G. B. Drew ◽  
Ashutosh Ghosh
Keyword(s):  
Schiff Base ◽  
Metal Ion ◽  
Magnetic Measurements ◽  
Dft Method ◽  
Distorted Octahedral Geometry ◽  
Schiff Base Ligands ◽  
Reduced Schiff Base ◽  
Ferromagnetic Interactions ◽  
Experimental Values ◽  
Reduced Schiff Base Ligands

Three trinuclear Ni(II)-Na(I) complexes,[Ni2(L1)2NaCl3(H2O)]·H2O (1), [Ni2(L2)2NaCl3(H2O)] (2), and [Ni2(L3)2NaCl3(OC4H10)] (3) have been synthesized using three different NNO donor tridentate reduced Schiff base ligands, HL1= 2-[(3-methylamino-propylamino)-methyl]-phenol, HL2= 2-[(3-methylamino-propylamino)-methyl]-4-chloro-phenol, and HL3= 2-[(3-methylamino-propylamino)-methyl]-6-methoxy-phenol that had been structurally characterized. Among these complexes, 1 and 2 are isostructural in which dinuclearNi(II) units act as metalloligands to bind Na(I) ions via phenoxido and chlorido bridges. The Na(I) atom is five-coordinated, and the Ni(II) atom possesses hexacordinated distorted octahedral geometry. In contrast, in complex 3, two -OMe groups from the dinuclear Ni(II) unit also coordinate to Na(I) to make its geometry heptacordinated pentagonal bipyramidal. The magnetic measurements of complexes 1–3 indicate ferromagnetic interactions between dimeric Ni(II) units with J = 3.97 cm−1, 4.66 cm−1, and 5.50 cm−1for 1–3, respectively, as is expected from their low phenoxido bridging angles (89.32°, 89.39°, and 87.32° for 1–3, respectively). The J values have been calculated by broken symmetry DFT method and found to be in good agreement with the experimental values.

scholarly journals Equilibria in Aqueous Cobalt(II)—Reduced Schiff Base N-(2-hydroxybenzyl)alanine System: Chemical Characterization, Kinetic Analysis, Antimicrobial and Cytotoxic Properties

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3462
Author(s):  
Magdalena Woźniczka ◽  
Manas Sutradhar ◽  
Armando J. L. Pombeiro ◽  
Mirosława Świątek ◽  
Marek Pająk ◽  
...  
Keyword(s):  
Schiff Base ◽  
Kinetic Analysis ◽  
Staphylococcus Epidermidis ◽  
Antimicrobial Properties ◽  
Chemical Characterization ◽  
Point Of View ◽  
Gram Negative Bacteria ◽  
Gram Positive Bacteria ◽  
Mononuclear Complexes ◽  
Reduced Schiff Base

The present study describes the coordination properties of a reduced Schiff base, N-(2-hydroxybenzyl)alanine, towards cobalt(II) using potentiometric as well as spectroscopic (UV-Vis and ESI-MS) methods. The results indicate the formation of six mononuclear complexes showing high stability in aqueous solution. Coordination occurs in the {O−phenolic,N,O−carboxyl} and {N,O−carboxyl} chelation modes, depending on the degree of ligand deprotonation. Examination of the complexation equilibria at pH ca 7, which is important from a biological point of view, allowed to identify two species: [CoL] and [CoL2H]−. The kinetic analysis showed a structural change of those cobalt(II) complexes from octahedral to tetrahedral in accordance with a first-order time relationship. The antimicrobial properties of N-(2-hydroxybenzyl)alanine, cobalt(II) nitrate and of the Co(II) – ligand complexes were determined against Gram-positive bacteria (Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis), Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Helicobacter pylori) and a fungal strain (Candida). The results indicate that the complexes are more active for more strains than the ligand alone. Nevertheless, the complexes induce a higher decrease in the metabolic activity of cells but without damage to nuclei. Tetrahedral structures show stronger anti-cellular toxicity than octahedral complexes, which is most likely due to the higher accessibility of the cobalt(II) center.

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