Structural characterization of copper complexes with chiral 1,2,4-triazine-oxazoline ligands

Wolińska, Ewa; Karczmarzyk, Zbigniew; Wysocki, Waldemar

doi:10.1515/hc-2016-0103

Cited by 9 publications

(15 citation statements)

References 22 publications

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“…The bonds and angles in molecules 5a-5c are very similar to those observed in previously reported closely related structures bearing a six-membered azaheteroaromatic ring linked with the chiral oxazoline ring by an anilino unit (Karczmarzyk et al, 2011;Woliń ska et al, 2016). As in the above-mentioned structures, in all the investigated molecules, the linker secondary N11-amine group is planar, with the sum of the angles around the N atom being 360, 359.6, 360 and 358.9 for 5a, 5b(A), 5b(B) and 5c, respectively, with an unusually large C2-N11-C12 angle of 131.6 (4) in 5a, 131.6 (3) in 5b(A), 131.5 (3) in 5b(B) and 131.9 (4) in 5c.…”

Section: Structure Analysissupporting

confidence: 84%

“…During our research, we developed ligands bearing a 1,2,4-triazine or pyridine ring linked with the chiral oxazoline by an anilino unit. The enantiocontrolling activity of the ligands was evaluated in the asymmetric nitroaldol reaction of nitromethane with a variety of aromatic and aliphatic aldehydes catalysed by copper ions (Woliń ska, 2013(Woliń ska, , 2014a(Woliń ska, ,b, 2016Woliń ska et al, 2016). This study revealed that the ligands with a 1,2,4-triazine ring exhibit a significantly higher enantio-inducing ability than the ligands possessing a pyridine ring due to the more electron-withdrawing character of the 1,2,4-triazine ring, which increases the positive charge of the copper cation centre and the electrophilicity of the aldehyde coordinating to the metal (Woliń ska et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…The enantiocontrolling activity of the ligands was evaluated in the asymmetric nitroaldol reaction of nitromethane with a variety of aromatic and aliphatic aldehydes catalysed by copper ions (Woliń ska, 2013(Woliń ska, , 2014a(Woliń ska, ,b, 2016Woliń ska et al, 2016). This study revealed that the ligands with a 1,2,4-triazine ring exhibit a significantly higher enantio-inducing ability than the ligands possessing a pyridine ring due to the more electron-withdrawing character of the 1,2,4-triazine ring, which increases the positive charge of the copper cation centre and the electrophilicity of the aldehyde coordinating to the metal (Woliń ska et al, 2016). In view of the above, introduction of electron-withdrawing substituents to the pyridine ring should result in an enhancement of the catalytic activity of the pyridine-containing oxazoline ligands.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and structures of three new pyridine-containing oxazoline ligands of complexes for asymmetric catalysis

Wolińska¹,

Wysocki²,

Branowska³

et al. 2021

Acta Crystallogr C Struct Chem

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Three new chiral pyridine-containing oxazoline derivatives with fluorine and perfluoromethyl groups, namely, 2-({2-[(4S)-4-phenyl-4,5-dihydro-1,3-oxazol-2-yl]phenyl}amino)-5-(trifluoromethyl)pyridine, C21H16F3N3O, 2-({5-fluoro-2-[(4S)-4-isopropyl-4,5-dihydro-1,3-oxazol-2-yl]phenyl}amino)-5-(trifluoromethyl)pyridine, C18H17F4N3O, and 2-({2-[(3aR,8aS)-8,8a-dihydro-3aH-indeno[1,2-d]oxazol-2-yl]phenyl}amino)-5-(trifluoromethyl)pyridine, C22H16F3N3O, as chiral ligands in metal-catalysed asymmetric reactions, were synthesized and characterized by spectral and X-ray diffraction methods. The conformation of the molecules is influenced by strong N—H...N hydrogen bonding and weak C—H...X (X = O and N) interactions. There are no intermolecular hydrogen bonds in the crystal structures of the analysed compounds. Hirshfeld surface analysis showed that the H...H contacts constitute a high percentage of the intermolecular interactions. The conformational analysis was performed by theoretical calculations using the density functional theory (DFT) method. The mechanism of complex formation in terms of the electron-withdrawing effect of the substituents on the oxazoline ring and the ligand conformation is discussed.

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Section: Structure Analysissupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and structures of three new pyridine-containing oxazoline ligands of complexes for asymmetric catalysis

Wolińska¹,

Wysocki²,

Branowska³

et al. 2021

Acta Crystallogr C Struct Chem

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“…210, 254, and 309 nm. The first two bands (210 and 254 nm) are due to the maleamato ligand, and the band at 309 is associated with the metal to ligand charge transfer (MLCT) which is usually observed in copper complexes [56].…”

Section: Resultsmentioning

confidence: 99%

Preparation and Study of the Antibacterial Applications and Oxidative Stress Induction of Copper Maleamate-Functionalized Mesoporous Silica Nanoparticles

et al. 2019

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Mesoporous silica nanoparticles (MSNs) are an interesting class of nanomaterials with potential applications in different therapeutic areas and that have been extensively used as drug carriers in different fields of medicine. The present work is focused on the synthesis of MSNs containing a maleamato ligand (MSN-maleamic) and the subsequent coordination of copper(II) ions (MSN-maleamic-Cu) for the exploration of their potential application as antibacterial agents. The Cu-containing nanomaterials have been characterized by different techniques and the preliminary antibacterial effect of the supported maleamato-copper(II) complexes has been tested against two types of bacteria (Gram positive and Gram negative) in different assays to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The biological results showed a moderate antibacterial activity against Escherichia coli which motivated a more detailed study of the antibacterial mechanism of action of the synthesized maleamate-containing nanosystems and whose findings showed oxidative stress generation in bacterial cells. All the prepared nanomaterials were also tested as catalysts in the “solvent free” selective oxidation of benzyl alcohol, to observe if there is a potential correlation between the catalytic oxidation capacity of the materials and the observed oxidative stress in bacteria. This may help in the future, for a more accurate rational design of antibacterial nanosystems, based on their observed catalytic oxidation activity.

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“…Chiral 3-oxazoline pyridine N-oxides substituted by with 1,2,4-triazine ring (50, 51) [68] were also examined in nitroaldol reaction of m-nitrobenzaldehyde but all attempts resulted in racemic nitroalcohol. An external base addition was tried and some improvement has been observed [69]. However, enantioselectivity grows (from racemate to 41% ee) only for bases with low pKa value.…”

Section: Chiral Heteroaromatic N-oxides As Ligands For Metal Catalysismentioning

confidence: 99%

Heteroaromatic N-Oxides in Asymmetric Catalysis: A Review

Wrzeszcz

Siedlecka

2020

Molecules

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An increasing interest in the synthesis and use of optically active pyridine N-oxides as chiral controllers for asymmetric reactions has been observed in the last few years. Chiral heteroaromatic N-oxides can work as powerful electron-pair donors, providing suitable electronic environments in the transition state formed within the reaction. The nucleophilicity of the oxygen atom in N-oxides, coupled with a high affinity of silicon to oxygen, represent ideal properties for the development of synthetic methodology based on nucleophilic activation of organosilicon reagents. The application of chiral N-oxides as efficient organocatalysts in allylation, propargylation, allenylation, and ring-opening of meso-epoxides, as well as chiral ligands for metal complexes catalyzing Michael addition or nitroaldol reaction, can also be found in the literature. This review deals with stereoselective applications of N-oxides, and how the differentiating properties are correlated with their structure. It contains more recent results, covering approximately the last ten years. All the reported examples have been divided into five classes, according to the chirality elements present in their basic molecular frameworks.

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Structural characterization of copper complexes with chiral 1,2,4-triazine-oxazoline ligands

Abstract: The crystal structure determination of oxazoline-1,2,4-triazine ligand

Cited by 9 publications

References 22 publications

Synthesis and structures of three new pyridine-containing oxazoline ligands of complexes for asymmetric catalysis

Synthesis and structures of three new pyridine-containing oxazoline ligands of complexes for asymmetric catalysis

Preparation and Study of the Antibacterial Applications and Oxidative Stress Induction of Copper Maleamate-Functionalized Mesoporous Silica Nanoparticles

Heteroaromatic N-Oxides in Asymmetric Catalysis: A Review

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