Synthesis, characterization and comparative study of a series of fluorinated Schiff bases containing different orientation CHN spacers

Pang, Wan; Zhao, Jingwei; Zhao, Lei; Zhang, Zhikai; Zhu, Shizheng

doi:10.1016/j.molstruc.2015.04.035

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…The selected ligand precursor was prepared following the standard procedure for this kind of compound. In the present study, we chose the proligand HL a that incorporates fluorine atoms in positions 2 and 3 of the iminic ring [45,53,54].…”

Section: Resultsmentioning

confidence: 99%

Aluminates with Fluorinated Schiff Bases: Influence of the Alkali Metal–Fluorine Interactions in Structure Stabilization

et al. 2018

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New heterometallic aluminium-alkali metal compounds have been prepared using Schiff bases with electron withdrawing substituents as ligands. The synthesis of these new species was achieved via the reaction of AlMe3 with the freshly prepared alkali-metallated ligand. The derivatives formed were characterized by NMR in solution and by single crystal X-ray diffraction in the solid state. Aluminate derivatives with lithium and sodium were prepared and a clear influence of the alkali metal in the final outcome is observed. The presence of a Na···F interaction in the solid state has a stabilization effect and the species [NaAlMe3L]2 can de isolated for the first time, which was not possible when using Schiff bases without electron withdrawing substituents as ligands.

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Section: Resultsmentioning

confidence: 99%

Aluminates with Fluorinated Schiff Bases: Influence of the Alkali Metal–Fluorine Interactions in Structure Stabilization

et al. 2018

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“…At the same time, bridge-flipped isomeric pairs that are not isomorphous may serve as seeds for the preparation of new polymorphs of their formerly non-isomorphous counterparts, providing yet another means for obtaining new solid materials. Isomorphism among bridge-flipped isomers is rare, commonly being prevented by differences in structural features such as preferred molecular conformations and favored intermolecular interactions that include hydrogen bonding and Lewis acid–base contacts. − On the other hand, several examples of isomorphous pairs are known. − Our search for isomorphous bridge-flipped isomers has employed the premise that similar intermolecular interactions occurring in the two isomers would promote their isomorphism. This strategy has been pursued successfully by previous workers who used strong hydrogen-bonding interactions between carboxylic acids and amides to obtain isomorphous crystals in a chloro/methyl exchange .…”

Section: Introductionmentioning

confidence: 99%

Bridge-Flipped Isomers: Searching for Isomorphous Benzylideneanilines and Phenylhydrazones Reveals Unexpected Structures

Kassekert

Smith

Fermanich

et al. 2019

Crystal Growth & Design

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Examination of a series of "bridge-flipped" halogen-and nitrile-substituted benzylideneanilines for isomorphism by single-crystal X-ray diffraction has resulted in the identification of three non-isomorphous pairs:Their crystal structures are rendered unique by differences in solid-state molecular conformation and intermolecular interactions. The crystal structures of N-(4-cyanobenzylidene)-2-bromoaniline (2Bran) and N-(4-cyanobenzylidene)-2-iodoaniline (2Ian) were determined, but upon attempts to prepare their bridge-flipped isomers the unexpected dianilines 1-(2-bromophenyl)-N,N′-bis(4-cyanophenyl)methanediamine (2Brdian) and 1-(2-iodophenyl)-N,N′-bis(4-cyanophenyl)methanediamine (2Idian) were obtained. The crystal structures of 2Brdian and 2Idian were found to be isomorphous, as were the crystal structures of the three pairs 2Clan/2Bran, 2Ian/2CH 3 an (N-(4-cyanobenzylidene)-2methylaniline), and 2CNan/XOXLOM (N-(4-methylbenzylidene)-2-cyanoaniline). Isomorphism involving iodine/methyl and nitrile/methyl exchanges is rare in the Cambridge Structural Database (CSD). The unexpected product meso-(E,E)-1,1′-[1,2bis(4-methylphenyl)ethane-1,2-diyl]-bis [(2-trifluoromethyl)phenyldiazene] (2CF 3 azo) was obtained in an attempt to prepare the phenylhydrazone, and its crystal structure is reported here. Only one other example of this type of compound currently appears in the CSD. Examples of isomorphous bridge-flipped isomers among benzylideneanilines and phenylhydrazones remain rare in spite of their conformational flexibility and steric similarity.

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“…The chain on the nitrogen makes the Schiff bases a stable imine. 9,10 Schiff bases appear to be important intermediates in a number of enzymatic reaction involving interaction of the amino group of an enzyme, usually that of a lysine residue, with a carbonyl group of the substrate. 11 In general, Schiff bases have a wide range of potential applications in various biological fields, 12 also fluorinated Schiff bases derivatives have been widely studied because they have antifungal, antibacterial, 1, 13, 14 DNA cleavage 15 and anticancer 16 activities which give it attracted remarkable attention.…”

Section: Introductionmentioning

confidence: 99%

Studies on The Synthesis of Fluorinated Schiff Bases; Biological Activity of Resulting (E)-N-Benzylidene-2,3,5,6-Tetrafluoropyridin-4-Amine and 4-Amino-2-Ethoxy-3,5,6-Trifluoropyridine

Raache¹,

Sekhri²,

Tabchouche³

2016

Orient. J. Chem

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The present work is aimed mainly to synthesize new fluorinated compounds and their biological significance against tested bacteria and fungus. Thus, the 4-amino-2-ethoxy-3,5,6-trifluoropyridine 4 was synthesized by the reaction of 4-amino 2,3,5,6-tetrafluoropyridine 1 with benzaldehyde 2 in EtOH to obtain the pure product as white crystals in 33% yield. The purity of this compound was estimated by TLC technique and microanalysis while its structure was supported by the usual spectroscopic methods such as UV, infrared, 1 H. NMR, and gas chromatography coupled by a mass spectrometry (GC/MS). 4-amino 2,3,5,6-tetrafluoropyridine 1 coupled readily to benzaldehyde 2 when we have used THF as solvent resulting a new Schiff base (E)-N-benzylidene-2,3,5,6-tetrafluoropyridin-4-amine 3 in 48 % yield. Exploration of the anti-bacterial activity against both gram-positive and gram-negative bacteria showed that these compounds 3 and 4 compounds at a concentration of 250 µg/ml exhibited a slight activity towards Enterococcus feacium; Streptocoque B and Staphylococus aureus exhibited a mild/moderate activity for the case of Escherichia coli and Salmonella typhimurium when compared to Ampicillin. From the results obtained by the antifungal activity, it is found that this fluorinated Schiff base 3 and fluorinated ethoxypyridine 4 are more active against Candida albicans at a concentration of 250 µg/ml when compared to Nystatine.

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Synthesis, characterization and comparative study of a series of fluorinated Schiff bases containing different orientation CHN spacers

Cited by 6 publications

References 21 publications

Aluminates with Fluorinated Schiff Bases: Influence of the Alkali Metal–Fluorine Interactions in Structure Stabilization

Aluminates with Fluorinated Schiff Bases: Influence of the Alkali Metal–Fluorine Interactions in Structure Stabilization

Bridge-Flipped Isomers: Searching for Isomorphous Benzylideneanilines and Phenylhydrazones Reveals Unexpected Structures

Studies on The Synthesis of Fluorinated Schiff Bases; Biological Activity of Resulting (E)-N-Benzylidene-2,3,5,6-Tetrafluoropyridin-4-Amine and 4-Amino-2-Ethoxy-3,5,6-Trifluoropyridine

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