- Synthesis, spectroscopic characterization and pH dependent photometric and electrochemical fate of Schiff bases
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A new Schiff base, 1-((4-bromophenylimino) methyl) naphthalen-2-ol (BPIMN) was successfully synthesized and characterized by 1H NMR, 13C NMR, FTIR and UV-Vis spectroscopy. The results were compared with a structurally related Schiff base, 1-((4-chlorophenylimino) methyl) naphthalen-2-ol (CPIMN). The photometric and electrochemical fate of BPIMN and CPIMN was investigated in a wide pH range. The experimental findings were supported by quantum mechanical approach. The redox mechanistic pathways were proposed on the basis of results obtained electrochemical techniques. Moreover, pH dependent UV-Vis spectroscopy of BPIMN and CPIMN was carried out and the appearance of isosbestic points indicated the existence of these compounds in different tautomeric forms.
- Rauf, Abdur,Shah, Afzal,Abbas, Saghir,Rana, Usman Ali,Khan, Salah Ud-Din,Ali, Saqib,Zia-Ur-Rehman,Qureshi, Rumana,Kraatz, Heinz-Bernhard,Belanger-Gariepy, Francine
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- Synthesis, Spectroscopic Characterization, and XAFS Studies of Cu(II) Complexes with Bidentate Schiff Bases Derived from 2-Hydroxy-1-Naphthaldehyde
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Abstract: The new complexes of compositions [CuL1] and [CuL2] were prepared by treating with [1-(((4-nitrophenyl)imino)methyl)naphthalene-2-ol] (L1) and [1-(((4-chlorophenyl)imino)methyl)naphthalene-2-ol] (L2) ligands with Cu(OAc)2·H2O, respectively. Both Schiff base ligand act as bidentate ligands. The complexes were investigated by single crystal X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM). The X-ray diffraction studies suggest a monoclinic crystal system for the complexes.
- Mishra, Ashutosh,Sharma, Pradeep,Shukla, Kritika
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p. S128 - S139
(2021/05/25)
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- Half-Sandwich Iridium Complexes for the One-Pot Synthesis of Amides: Preparation, Structure, and Diverse Catalytic Activity
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Several types of air-stable N,O-coordinate half-sandwich iridium complexes containing Schiff base ligands with the general formula [Cp*IrClL] were synthesized in good yields. These stable iridium complexes displayed a good catalytic efficiency in amide synthesis. A variety of amides with different substituents were obtained in a one-pot procedure with excellent yields and high selectivities through the amidation of aldehydes with NH2OHHCl and nitrile hydration under the catalysis of complexes 1-4. The excellent and diverse catalytic activity, mild conditions, broad substance scope, and environmentally friendly solvent make this system potentially applicable in industrial production. Half-sandwich iridium complexes 1-4 were characterized by NMR, elemental analysis, and IR techniques. Molecular structures of complexes 2 and 3 were confirmed by single-crystal X-ray analysis.
- Fan, Xiao-Nan,Deng, Wei,Liu, Zhen-Jiang,Yao, Zi-Jian
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p. 16582 - 16590
(2020/11/13)
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- Efficacy of novel schiff base derivatives as antifungal compounds in combination with approved drugs against candida albicans
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Background: The increasing incidence of fungal infections, especially caused by Candida albicans, and their increasing drug resistance has drastically increased in recent years. Therefore, not only new drugs but also alternative treatment strategies are promptly required. Methods: We previously reported on the synergistic interaction of some azole and non-azole compounds with fluconazole for combination antifungal therapy. In this study, we synthesized some non-azole Schiff-base derivatives and evaluated their antifungal activity profile alone and in combination with the most commonly used antifungal drugs-fluconazole (FLC) and amphotericin B (AmB) against four drug susceptible, three FLC resistant and three AmB resistant clinically isolated Candida albicans strains. To further analyze the mechanism of antifungal action of these compounds, we quantified total sterol contents in FLC-susceptible and resistant C. albicans isolates. Results: A pyrimidine ring-containing derivative SB5 showed the most potent antifungal activity against all the tested strains. After combining these compounds with FLC and AmB, 76% combinations were either synergistic or additive while as the rest of the combinations were indifferent. Interestingly, none of the combinations was antagonistic, either with FLC or AmB. Results interpreted from fractional inhibitory concentration index (FICI) and isobolograms revealed 4-10-fold reduction in MIC values for synergistic combinations. These compounds also inhibit ergosterol biosynthesis in a concentration-dependent manner, supported by the results from docking studies. Conclusion: The results of the studies conducted advocate the potential of these compounds as new antifungal drugs. However, further studies are required to understand the other mechanisms and in vivo efficacy and toxicity of these compounds.
- Malik, Manzoor Ahmad,Lone, Shabir Ahmad,Gull, Parveez,Dar, Ovas Ahmad,Wani, Mohmmad Younus,Ahmad, Aijaz,Hashmi, Athar Adil
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p. 646 - 656
(2019/08/30)
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- Syntheses, characterization and catalytic activities of half-sandwich ruthenium complexes with naphthalene-based Schiff base ligands
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Four ruthenium(II) p-cymene complexes with naphthalene-based Schiff base ligands [Ru(p-cymene)LCl] (2a–2d) have been synthesized and characterized. The half-sandwich ruthenium complexes were characterized by 1H and 13C NMR spectra, elemental analyses, and infrared spectrometry. The molecular structures of 2a, 2b, and 2c were confirmed by single-crystal X-ray diffraction. Furthermore, these half-sandwich ruthenium complexes are highly active catalysts for the hydrogenation of nitroarenes to anilines using NaBH4 as the reducing agent in ethanol at room temperature.
- Jia, Wei-Guo,Wang, Zhi-Bao,Zhi, Xue-Ting,Han, Jia-Qin,Sun, Ying
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p. 848 - 858
(2017/02/26)
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- Synthesis of a series of new platinum organometallic complexes derived from bidentate Schiff-base ligands and their catalytic activity in the hydrosilylation and dehydrosilylation of styrene
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The synthesis and properties of a novel class of platinum complexes containing Schiff bases as O,N-bidentate ligands is described as are the solution and solid state properties of the uncomplexed ligands. The platinum complexes were prepared from [PtBr2(COD)] (COD = 1,5-cyclooctadiene) and N-(2-hydroxy-1-naphthalidene)aniline derivatives in the presence of base (NaOBut). Instead of a substitution reaction to afford cationic species, the addition of the Schiff base ligands results in both the formal loss of two equivalents of bromide and addition of hydroxide to the COD ligand of the complexes. It is proposed that this reaction proceeds through a cationic platinum complex [Pt(N-O)(COD)]Br which then undergoes addition of water and loss of HBr. An example of a dinuclear platinum complex in which two cyclo-octene ligands are bridged by an ether linkage is also reported. The platinum complexes were evaluated as catalysts for the hydrogenative and dehydrogenative silylation of styrene, the resulting behaviour is substituent, time and temperature dependent.
- Lachachi, M. Belhadj,Benabdallah, Tayeb,Aguiar, Pedro M.,Youcef, M. Hadj,Whitwood, Adrian C.,Lynam, Jason M.
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p. 11919 - 11928
(2015/06/30)
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- Synthesis, spectroscopic characterization, catalytic and antibacterial studies of ruthenium(III) Schiff base complexes
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The bidentate Schiff base ligands (HLn) have been synthesized by condensation of 2-hydroxy-l-naphthaldehyde with aniline and its p-substituted derivatives in ethanol. Ruthenium(III) complexes of the type [Ru(Ln)2(H2O)2]Cl have been synthesized by the reaction of RuCl3·nH2O with the Schiff base ligands (in a molar ratio 1:2) in ethanol. The ligands and their Ru(III) complexes have been characterized by elemental analysis, magnetic susceptibility, spectroscopic (FTIR, UV-vis, 1H NMR and X-ray diffraction) and thermal analysis techniques. All the ruthenium(III) complexes are found to be stable, paramagnetic, low spin and octahedrally coordinated by the ligands through the nitrogen atom of the azomethine (-CN-) group and the oxygen atom of the deprotonated phenolic group. The molecular and electronic structures of the investigated ligands (HLn) were also studied using quantum chemical calculations. The complexes (1, 3 and 5) exhibited a catalytic activity for the oxidation of benzoin to benzil with moderate to high yield in the presence of sodium periodate as co-oxidant. The antibacterial activities of the ligands (HLn) and their Ru(III) complexes towards Gram positive and Gram negative bacteria have been investigated.
- Shoair,El-Shobaky,Abo-Yassin
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p. 217 - 227
(2015/08/03)
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- Aqueous extract of the pericarp of Sapindus trifoliatus fruits: A novel 'green' catalyst for the aldimine synthesis
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The catalytic efficiency in organic synthesis of the aqueous extract of the pericarp of Sapindus trifoliatus fruits was evaluated. The synthesis of a series of aldimines from aromatic aldehydes and amines was successfully catalyzed by the extract, whereas aromatic ketones and amines did not yield ketimines under comparable reaction conditions, indicating the chemoselective catalysis of the extract. The catalytic activity of the extract is due to saponins, which have a common structural skeleton containing a pentacyclic triterpenoid part substituted with different carbohydrate side chains. The mild conditions, high yields, and short reaction times not only make this protocol a valuable alternative to the conventional methods, but it also becomes significant under the roof of environmentally greener and safer processes.
- Pore, Santosh,Rashinkar, Gajanan,Mote, Kavita,Salunkhe, Rajeshri
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experimental part
p. 1796 - 1800
(2011/08/05)
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- Synthesis and Characterization of Dioxouranium(VI) Complexes of Schiff Bases Derived from 2-Hydroxy-1-Naphthaldehyde
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A series of 20 new complexes of dioxouranium(VI) with Schiff bases derived from 2-hydroxy-naphthaldehyde with different aromatic amines with the general composition UO2X2*2L (X = Cl, Br, I, NO3 or NCS and L = Schiff bases) were synthesized.They were chara
- Agarwal, R. K.,Puneet,Dutt, P.
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p. 567 - 573
(2007/10/02)
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- Synthesis and Characterisation of Binuclear Silicon-Aluminium and Arsenic-Aluminium Complexes with Schiff Bases
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Trimethylsilyl acetate or phenylarsonic acid on reaction with aluminium isopropoxide yields two new series of complexes of the types, (CH3)3Si-O-Al(OPri)2 and .The isopropoxy groups in these derivatives further undergo facile reactions with bidentate Schiff bases giving coloured complexes of the types (CH3)3Si-O-Al(SB-H)2 and respectively, where SB-H is deprotonated form of the Schiff base.The Si-Al type of compounds are monomeric in nature and nonelectrolytes in DMF and DMSO, where the As-Al type of derivatives are insoluble in most of the organic solvents and appear to be polymeric in nature.A few compounds have been found to be quite effective as potential pesticides.
- Chaturvedi, Vibhav,Tandon, J. P.
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p. 422 - 424
(2007/10/02)
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