Parent Schiff Base Research Articles

Novel Ni(II) and Zn(II) Schiff base metal chelates as promising DNA binder, Antioxidant and Antifungal agents

<p>Schiff base ligands and their 3d-metal chelates have gained significant attention due to various applications in various scientific platforms. Due to their chelating propensity, they possess a wide range of biological, biochemical, catalytic, clinical, dying, and pharmacological properties.<strong> </strong>Here, in present studies,<strong> </strong>two novel Ni(II) and Zn(II) transition metal chelates have been synthesized by condensing their metal salts with Schiff base ligand 4-chloro-2-(2,5-dimethoxybenzylideneamino)-5-nitrophenol<strong> </strong>originated from 2,5-dimethoxybenzaldehyde and 2-amino-4-chloro-5-nitrophenol. The synthesized Schiff base ligand and its metal chelates have been Spectro-chemically examined by FT-IR, UV-Vis absorption spectroscopy, Mass Spectrometry, <sup>1</sup>HNMR, Thermogravimetric analysis (TGA) and Powdered-XRD. These compounds are biologically reactive and exhibit antifungal, antioxidant, and DNA-binding activity. The Ni(II) metal chelate gives better biological activity than the Zn(II) metal chelate and parent Schiff base ligand.</p>

Comprehensive investigation of Co(II), Ni(II) and Cu(II) complexes derived from a novel Schiff base: Synthesis, characterization, DNA interactions, ADME profiling, molecular docking, and in-vitro biological evaluation

Here, anisidine-based ligand (HL) and its cobalt (1a), nickel (1b) and copper (1c) complexes were synthesized and characterized by various spectroscopic techniques such as NMR, mass, IR, UV–visible, magnetic moments, ESR and TGA. The synthesized [Ni(L)2] and [Cu(L)2] complexes demonstrated square planar geometry around the metal centers, while the cobalt complex [Co(L)2(H2O)2] adopted six coordinated octahedral geometries. The DNA interaction studies of the complexes revealed an intercalative mode of binding, as evidenced by UV absorption, emission, and viscosity experiments, and the binding constant (Kb) follows the order of 1c > 1a > 1b. When exposed to oxidative and photolytic methods, the complexes demonstrated better efficacy in cleaving double-stranded pBR322 DNA compared to their parent Schiff base. When tested for cytotoxicity against A549 and MCF7 cell lines, complexes showed more activity than their parent ligand. In-vitro studies of the complexes' antimicrobial and antioxidant properties shown that they are far more effective than the parent ligand. Further, the biological efficiency of the ligand (HL) and complexes were verified by computational methods, including molecular docking (against protein data bank PDB ID: 2ADO.pdb) and pharmacokinetic studies, both the ligand (HL) and complexes have demonstrated significant potency. This promising result indicated their potential as therapeutic agents for treating pathogen-induced deformities.

Antibacterial properties of binuclear Zn(II)-azomethine complexes derived from diaminodiphenylsulphide bridged spacer

Antimicrobial resistance of microbes against treatment that once could cure, has inspired an urgent need for new drugs development. Accordingly, three binuclear Zn(II)-Schiff bases complexes ZnLa - ZnLc were prepared by direct reaction of the ligands La-Lc with Zn(II) ions in equimolar ratios bearing salicyldehydes with OH, NO2 and Cl functional groups. The synthesized compounds ZnLa - ZnLc were evaulated against Gram positive (Enterococcus faecalis NCIMB 13280, Streptococcus mutant ATCC 25175™ and Staphylococcus aureus ATCC 6538™) and gram negative (Escheria coli NCTC 12900, Salmonella typhi and Pseudomonas aeruginosa ATCC 15442) bacterial strains, respectively, by agar well diffusion and broth microdilution techniques. The minimum inhibitory concentration (MIC90) values were calculated by microplate reader at 550 nm to optimum result. It was found that all the synthesized compounds showed promising antibacterial activity against the genus Streptococcus mutant followed Staphylococcus aureus and Escheria coli. Binuclear Zn(II) complexes had a superior antibacterial activity compared to their parent Schiff base ligands. In general, 3,4-dihydroxy derived Schiff bases alongwith their relevant complexes exhibited magnificent antibacterial activity and hence merits to be established as promising keystone for subsequent antimicrobial drug advancement.

SYNTHESIS, SPECTRAL CHARACTERIZATION AND ANTIMICROBIAL STUDIES OF BIS(CYCLOPENTADIENYL)- ZIRCONIUM(IV) DERIVATIVES WITH QUINAZOLINONE SCHIFF BASES

Zirconium(IV) complexes of types [(C5H5)2Zr(L)] and [(C5H5)Zr(LÂ’)Cl] (LH2 represents Schiff bases derived from quinazolinone and salycylaldehye or o-hydroxyacetophenone LÂ’H represents Schiff bases derived from quinazolinone and 4-fluorobenzaldehyde/ 4-fluoro acetophenone /1-(2-fluoro-4-methylphenyl)-2-methylpropan-1-one / 1-(2-fluoro-4-methylphenyl) propan-1-one ) have been synthesized by the reactions of bis(cyclopentadienyl)zirconium(IV) dichloride with appropriate ligands in tetrahydrofuran in the presence of triethylamine. All these complexes are soluble in THF, PhNO2, DMF and DMSO. The complexes were characterized by elemental analyses, electrical conductance, magnetic susceptibility, IR, 1H NMR, XRD and SEM spectral techniques. Low molar conductance values indicate non-electrolytic nature of the complexes. The spectral data indicate 5-coordinate geometry for the complexes. XRD pattern evince that the complexes have monoclinic crystal system and particle sizes were found in the range 46.40-49.30 nm (nano-size). In vitro antifungal activity of synthesized compounds was evaluated against fungi Aspergillus niger, Aspergillus fumigatus, Candida albicans and In vitro antibacterial activity was determined by screening the compounds against gram negative (P. aeruginosa, E.coli) and gram positive (S. aureus and B. subtilis) bacterial strains using minimum inhibition concentration method (MIC) by serial dilution technique. The zirconocene(IV) complexes have higher antimicrobial impact than the parent Schiff bases.

Supramolecular encapsulation of nanocrystalline Schiff bases into β-cyclodextrin for multifold enrichment of bio-potency

We report the solvent-free green synthesis of two Schiff bases, (E)-2-((2-hydroxy-3-methoxybenzylidene)amino)-4-methylphenol (SL1) and (E)-2-((2-hydroxybenzylidene) amino)-4-methylphenol (SL2), and their inclusion complexes with β-cyclodextrin (β-CD). The encapsulation phenomenon, structural characteristics and hydrolytic stabilities of the SL1, SL2 and their inclusion complexes are determined with a suite of spectroscopic, analytical and crystallographic analyses. Dose and time-dependent cytotoxicity study of SL1-β-CD and SL2-β-CD against two breast cancer cell lines, Michigan Cancer Foundation-7 (MCF-7) and metastatic mammary adenocarcinoma1 (MDA-MB-231), exhibit excellent inhibitory activity with significant non-cytotoxic concentrations and ensure a multifold elevation of bio-potency than the parent Schiff base compounds. The Annexin-V assay determines the efficacy of these inclusion complexes to trigger apoptosis, suggesting that SL2-β-CD possesses better efficacy as an anti-cancer drug. To the best of our knowledge, we, for the first time, report the inclusion of nanocrystalline Schiff bases into β-CD for multifold enrichment of bio-potency.

Synthesis, spectral characterization and antibacterial activity of transition metal (II) complexes of tetradentate Schiff base ligand

Nickel, zinc and cadmium complexes of a Schiff base derived from 4-nitro-o-phenylenediamine and 5-methoxysalicylaldehyde were synthesized and characterized using infrared, ultra violet, molar conductance measurements and nuclear magnetic resonance spectroscopy. Tetradentate schiff base complexes are widely used for the industrial purpose and also exhibit the wide range of biological activities. Hence the antibacterial activity of the Schiff base ligand and the metal complexes against some clinically important bacteria namely Escherichia coli, Proteus mirabilis, Streptococcus pneumoniae, Bacillus subtilis were investigated and the obtained results have shown that the complexes were possesses more antibacterial activity than the parent Schiff base ligand and hence could be potentially used in the preparation of anti bacterial agents.

SYNTHESIS, SPECTRAL CHARACTERIZATION AND ANTIMICROBIAL ACTIVITIES OF BIS(CYCLOPENTADIENYL)TITANIUM(IV) COMPLEXES WITH SCHIFF BASES DERIVED FROM5-(SUBSTITUTED ARYL)-2-HYDRAZINO-1, 3, 4-OXADIAZOLE AND INDOLINE-2, 3-DIONE

Titanium(IV) complexes of type[(η5-C5H5)2TiCl(L)] have been synthesized by the reactions of bis(cyclopentadienyl)titanium(IV)dichloride with Schiff bases (LH) derived by the condensation of 5-(substituted aryl)-2-hydrazino-1,3,4-oxadiazole and indoline-2,3-dione in tetrahydrofuranin the presence oftriethylamine. All these complexes are soluble in PhNO2, DMF and DMSO.The complexes were characterized by elemental analyses, electrical conductance, magnetic susceptibility, UV-Vis, IR, 1H NMR, 13C NMR, XRD and SEM spectral techniques. Low molar conductance values indicate that they are non-electrolytes. The spectral data indicate5-coordinate geometry for the complexes.XRD pattern indicate that the complexes have monoclinic crystal system and particle sizes were found 49.36 nm (nano-size). In vitro antifungal activity of synthesized compounds was evaluated against fungi Aspergillusniger, Aspergillusflavus,ColletotrichumfalcatumandIn vitro antibacterial activity was determined by screening the compounds against gram negative (P. aeruginosa, S.typhi) and gram positive (S. aureus and B.subtilis) bacterial strains using minimum inhibition concentration method (MIC) by serial dilution technique. The titanocene(IV) complexes have higher antimicrobial effect than the parent Schiff bases.

Synthesis, structural characterization, CT-DNA interaction study and antithrombotic activity of new ortho-vanillin-based chiral (Se,N,O) donor ligands and their Pd complexes

Two new selenated ligands: (S)-BnSeCH2CH(Bn)N = CH-C6H3-3-OCH3-2-OH ((S)-L1H) and (S)-BnSeCH2CH(Bn)NH-CH2-C6H3-3-OCH3-2-OH ((S)-L2H) incorporating ortho-vanillin moiety and their respective palladium(II) complexes (S)-1 and (S)-2 were synthesized in a high-yielding procedures. All compounds were characterized by various spectroscopic techniques such as 1H, 13C{1H} NMR, FT-IR, and UV–Visible. Further, the elemental and single crystal X-ray diffraction analyses of complexes showed that the deprotonated ligands ((S)-L1 and (S)-L2) coordinated to central palladium as tridentate (Se,N,O−) chelates of composition [PdCl(L1-2)]. In crystalline state the molecules of complexes were found to held by a moderate to strong intermolecular hydrogen bonds like CH⋯Cl and CH⋯O in both and OH⋯O, OH⋯Cl, NH⋯Cl in (S)-2∙H2O. In addition, there exists rare CH⋯Se and Se⋯O types of secondary bonding interactions between the molecules of (S)-1 and (S)-2∙H2O respectively. The interactions of ligands and complexes with CT-DNA have been studied by absorption, fluorescence and viscosity measurements. These determinants showed efficient binding interaction with DNA through ‘intercalation’ mode. The reduced Schiff base showed a higher binding capacity than the parent Schiff base. Further, the DNA binding affinity of complexes is higher than the corresponding ligands. The anticoagulant and non-haemolytic activities have also been investigated for these compounds. The human blood clotting time found to be enhanced from 150 to 200 sec in both PPP and PRP cases on coordination of ligands to palladium.

Synthesis, structural characterisation and antibacterial activities of lead(II) and some transition metal complexes derived from quinoline-2-carboxaldehyde 4-methyl-3-thiosemicarbazone

Some metal complexes of formulae, [PbHNNS(NO3)2], [Cu(NNS)], [Zn(NNS)2], [Ni(NNS)2] and [Cd(NNS)2] (NNS = anionic form of the Schiff base of quinoline-2-carboxaldehyde 4-methyl-3-thiosemicarbazone) have been synthesised and structurally characterised by a variety of physico-chemical techniques. The crystal structure of [PbHNNS(NO3)2] and [Zn(NNS)2] have also been determined by X-ray crystallography. The mono-ligated nitrato-complex adopts a distorted square pyramidal geometry where the thiosemicarbazone ligand coordinates to the lead(II) ion as a uninegatively charged bidentate NS chelating agent via the azomethine nitrogen atom and the thiolate sulphur atom. The third and fourth coordinations are occupied by two nitrato ligands. In the bis-ligand zinc(II) complex [Zn(NNS)2], the zinc atom adopts a distorted octahedral geometry around the zinc(II) ion, with two uninegatively charged tridentate NNS thiosemicarbazone ligands coordinating via one of the quinoline nitrogen atom, the azomethine nitrogen atom and the mercaptide sulphur atom displaying meridional coordination. Some of the metal complexes exhibit greater antibacterial activity against the Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, as compared to the parent Schiff base ligand.

Palladium complexes of NO type Schiff bases: synthesis, characterization and antioxidant activities

The reaction of o-aminophenol with para hydroxy and methoxy substituted benzaldehydes yielded two Schiff bases. These Schiff bases functioning precursors were turned into palladium complexes by treating palladium acetate. The structural formulas based on spectral methods (elemental analysis, FT-IR spectroscopy, NMR spectroscopy and QTOF-LC/MS spectroscopy) were suggested for obtained both complexes. According to the structural characterization methods, one of the complexes had also an acetate co-ligand along with the hydroxy substituted Schiff base ligand. In the other complex, the palladium central ion was proposed to be coordinated with two methoxy substituted Schiff bases. Besides, DPPH scavenging activities of the all synthesized compounds were determined and compared to well-known antioxidant standards. According to the results, antioxidant activities of the palladium complexes was mild but lower than parent Schiff bases.

Designing, spectroscopic characterization, biological screening and antioxidant activity of mononuclear transition metal complexes of bidentate Schiff base hydrazones

In this article, a series of coordination complexes of Co(II), Ni(II), Cu(II) and Zn(II) metals were prepared by four novel Schiff base ligands (E)-N’-(4-(prop-2-yn-1-yloxy)benzylidene)benzohydrazide (HL1), (E)-4-chloro-N’-(4-(prop-2-yn-1-yloxy)benzylidene)benzohydrazide (HL2), (E)-N’-((2-(benzyloxy)naphthalen-1-yl)methylene)benzohydrazide (HL3), (E)-N’-((2-(benzyloxy)naphthalen-1-yl)methylene)-4-chlorobenzohydrazide (HL4) obtained by the condensation reaction of benzoic acid hydrazide/4-chloro benzoic acid hydrazide with oxy derivatives of 2-hydroxy-1-napthaldehyde/4-hydroxy benzaldehyde. The proposed structure of the complexes have been established by spectroscopic and analytical techniques like C, H, N and metal analysis, FT-IR, 1H and 13C NMR, mass, UV-Vis, EPR, fluorescence, molar conductance, magnetic susceptibility and TGA which concluded that Schiff bases act as bidentate NO donor ligands coordinating through nitrogen atom of azomethine linkage and uninegative oxygen atom of carbonyl group in enolic form and resulting in complexes of the type [M(L1–4)·(CH3COO)·3H2O] in 1:1 molar ratio. The synthesized compounds were screened for their in vitro antimicrobial activities against two gram +ve bacteria i.e. S. aureus and S. gordonii; two gram -ve bacteria i.e. E. coli and P. aeruginosa and two fungal strains i.e. A. niger and C. albicans and found that metal chelates were more noxious than their parent Schiff bases. The copper(II) complex 19 was found to be the highest noxious antimicrobial active compound. The compounds were also assessed for their antioxidant activity and found that the complexes are more potent and show excellent efficiency in decolorizing the DPPH purple colored solution than their free ligands. The complexes 6, 7, 10, 11, 14, 15, 18, 19 were found to be excellent antioxidants and copper(II) complexes were the most potent antioxidant compounds with lowest IC50 values (2.04–2.56 µM)) among all the tested compounds. Total 20 compounds of Schiff bases transition metal complexes were synthesized and characterized. The copper complex (19) was found to be highest antimicrobial against Streptococcus gordonii, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, Candida albicans. The copper(II) complex (11) exhibits outstanding and highest antioxidant activity (IC50 = 2.04 µM).

Synthesis, crystal structure, theoretical calculation, spectroscopic and antibacterial activity studies of copper(II) complexes bearing bidentate schiff base ligands derived from 4-aminoantipyrine: Influence of substitutions on antibacterial activity

A novel series of Cu(II) complexes, including: [Cu(L1)2]: C1, [Cu(L2)2]: C2, [Cu(L3)2]: C3, [Cu(L4)2]: C4, with four bis-N,O-bidentate Schiff base ligands (HL1: (E)-4-[(2‑hydroxy-3-methoxybenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one; HL2: (E)-4-[(2‑hydroxy-4-methoxybenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one; HL3: (E)-4-[(2‑hydroxy-5-methoxybenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one; HL4: (E)-4-[(2‑hydroxy-6-methoxybenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one have been synthesized and characterized by elemental analyses, FT-IR, 1H NMR and 13C NMR spectroscopic techniques. Furthermore, the crystal structures of HL4 and C2 were determined by single crystal X-ray analysis. Single crystal X-ray analyses, the structure of C2 confirmed the bidentate coordination mode. The metal center possesses a distorted tetrahedral geometry with bis-N,O donor atoms coordinating from Schiff base ligand. Theoretical calculation of the synthesized compounds were carried out by DFT using B3LYP method with employing the Def2-SVPD (for ligands) and Def2-SV(P) (for complexes) basis sets. Calculated data are in good accordance with the experimental investigations. The in vitro biological activities of the synthesized ligands and their copper(II) complexes were evaluated against Staphylococcus aureus and Escherichia coli. The activity data showed that the metal complexes have a promising biological potential comparable with the parent Schiff base ligands against bacterial species.

Chemistry of Tetradentate [C,N : C,N] Iminophosphorane Palladacycles: Preparation, Reactivity and Theoretical Calculations.

A theoretical and experimental study of tetradentate [C,N : C,N] iminophosphorane palladacycles was carried out for the purpose of elucidating their behavior as compared to the parent Schiff base analogues to determine the prospect of encountering new A‐frame structures for the iminophosphorane derivatives. The DFT calculations were in agreement with the experimental results regarding the performance of these ligands. New insights into the chemistry of the related dinuclear species have been obtained.

Biological Evaluation of Synthesized Schiff Base-Metal Complexes Derived from Sulfisomidine

Inflammation characterized by edema, redness, and pain predominantly symptomatizes in diseases like allergies, asthma, and arthritis. Anti-inflammatory drugs like NSAIDs have been used to treat inflammation but reportedly cause severe gastrointestinal problems; therefore, new and safer drugs are sought-after for better resolution of diseases. The metal-based drugs have been proved as promising alternatives for some of the currently used drugs. The aim of this study was to evaluate antioxidant, antibacterial, and in vivo and in vitro anti-inflammatory activities of new Schiff base derived metal complexes. The antioxidant, antibacterial, and in vivo and in vitro anti-inflammatory activities were performed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), agar well diffusion, paw edema, and egg albumin denaturation methods respectively. Mn (II) and Co (II) complexes showed 0.65 and 1.91 IC50 values and other complexes showed compelling ABTS antioxidant activity. Cu (II) and Zn (II) complexes exhibited significant antimicrobial activity against all six bacterial strains as compared with the parent Schiff base ligand. The in vitro anti-inflammatory activity revealed that all the complexes inhibited inflammation in dose-dependent manner, while in vivo results indicated Ni (II) complex as potential anti-inflammatory agent. Hence our drugs were found to be potent antioxidant, antibacterial, as well as anti-inflammatory agents and might be used to suppress disease severity by inhibiting the inflammation.

Exceptionally Plastic/Elastic Organic Crystals of a Naphthalidenimine-Boron Complex Show Flexible Optical Waveguide Properties.

The design of molecular compounds that exhibit flexibility is an emerging area of research. Although a fair amount of success has been achieved in the design of plastic or elastic crystals, realizing multidimensional plastic and elastic bending remains challenging. We report herein a naphthalidenimine-boron complex that showed size-dependent dual mechanical bending behavior whereas its parent Schiff base was brittle. Detailed crystallographic and spectroscopic analysis revealed the importance of boron in imparting the interesting mechanical properties. Furthermore, the luminescence of the molecule was turned-on subsequent to boron complexation, thereby allowing it to be explored for multimode optical waveguide applications. Our in-depth study of the size-dependent plastic and elastic bending of the crystals thus provides important insights in molecular engineering and could act as a platform for the development of future smart flexible materials for optoelectronic applications.

Solvent Free Synthesis and Characterization of Few Metal Complexes of Schiff Base Derived from 2-Amino-5, 6-dimethyl Benzimidazole and Syringaldehyde

A solvent-free synthesis of bidentate Schiff base ligand was carried out by treating 2-Amino-5, 6-dimethyl benzimidazole with Syringaldehyde in 1:1 molar proportion in a scientific microwave oven. The excellent yield was obtained after purification. Few metal complexes of Schiff base were synthesized by using Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Ag(I) metal salts in microwave oven under solvent-freecondition. All metal complexes showed distinct color at the end of the reaction, and the melting point of each complex preliminary confirmed the formation of the product. A detailed characterization of both Schiff base and its representative metal complexes was carried out by several analytical and spectral techniques, including elemental analysis, Infrared (IR) spectroscopy, 1 HNMR spectroscopy, liquid chromatography– mass spectrometry (LCMS), UV spectroscopy, and TGA. The spectroscopic analysis supports the predicted structure of the parent Schiff base ligand. Bioactivity of Schiff base and respective metal complexes was studied against Escherichia coli, Staphylococcus aureus and Salmonella typhi showing significant bioactivity of the metal complexes and Schiff base ligand.

Transition metal complexes of Schiff base ligand based on 4,6‐diacetyl resorcinol

Novel Schiff base ligand based on the condensation of 4,6‐diacetyl resorcinol with 2‐amino‐4‐methylthiazole in addition to its metal complexes with Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II), Zn (II) and Cd (II) ions have been synthesized. The structure, electronic properties, and thermal behaviour of Schiff base and its metal complexes have been studied by elemental analysis, mass, 1H NMR, IR spectra, thermal analysis, and theoretically by density function theory. The ligand acted as mononegative bidentate (NO) ligand and all complexes showed octahedral geometry except Cu (II) showed tetrahedral geometry as indicated from the spectral and magnetic studies. The Cu (II), Zn (II) and Cd (II) complexes were non electrolytes while the rest of the complexes were electrolytes. The antibacterial plus anticancer activities of the parent Schiff base and its metal complexes were screened. In addition, the molecular docking study was performed to explore the possible ways for binding to Crystal Structure of Human Astrovirus capsid protein (5ibv) receptor.

Nano-sized some transition metal complexes of Schiff base ligand based on 1-aminoquinolin-2(1H)-one

The novel Schiff base ligand that is based on the condensation of 1-aminoquinolin-2(1H)-one and 2-hydroxybenzaldehyde and its metal complexes with Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Hg(II) ions have been synthesized. Furthermore, the structure, electronic properties, and chemical reactivity of Schiff base and its metal complexes have been examined via Elemental analysis, Mass, (1H, 13C and 15N) NMR, FT-IR, CV, ESR spectra, Thermal analysis, and theoretically using the density functional theory. Initially, the ligand behaved as a neutral tridentate (NOO) ligand and all complexes displayed octahedral geometry, except Hg(II), which showed tetrahedral geometry. The values of molar conductance in DMSO suggested the non-electrolytic nature for all complexes. The coordinated and crystalline water molecules have been investigated by (TG/DTG) studies. The kinetic and thermodynamic parameters were computed using Horowitz–Metzger and Coats–Redfern methods. Moreover, the data obtained from XRD, SEM, TEM, EDX and AFM images unequivocally asserted the nano-sized metal chelates. In molecular modelling the geometries of Schiff base and its nano-sized Cu(II), Co(II) and Zn(II) hybrids were fully optimized with respect to the energy generated due to using the DFT method from DMOL3 calculations. The anticancer activity of the parent Schiff base and its nano-sized metal hybrids were screened, in addition to the interaction of the complexes with calf thymus CT–DNA, which was investigated via the UV–visible absorption method. Additionally, the mode of CT‒DNA binding to the HL ligand and its nano-sized hybrids has been explored. Therefore the DNA cleavage activity by the HL ligand and its nano-sized hybrids was performed allowing the measurement of the solid-state dc electrical conductivity of the HL ligand and its nano-sized Co(II), Cu(II) and Zn(II) hybrids over 303–423 K, which were then found to be of semiconducting nature.

Theoretical studies of new Schiff base ligand derived from 1,3‐diaminopropane and 2‐acetyl ferrocene and studying some applications of its metal complexes

A novel bidentate Schiff base ligand (L) and some d‐transition metal chelates (Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II), Zn (II) and Cd (II)) were synthesized and characterized using various physicochemical and spectroscopic techniques like elemental analysis, IR, mass, UV–visible and thermal analysis. The spectroscopic data suggested that the parent Schiff base ligand coordinated to the metal ions through both imine nitrogen atoms. The molecular and electronic structure of the free ligand was optimized theoretically, and the quantum chemical parameters were calculated. The molecular structure can be used to investigate the coordination sites and the total charge density around each atom. The free ligand and its complexes were screened for their antimicrobial activities for various pathogenic bacteria and fungi. The anticancer activities of the free ligand, Cr (III), Mn (II) and Fe (III) complexes were screened against MCF‐7 cell line and found that Mn (II) complex has the lowest IC50 (15.90 μg/ml). Molecular docking was used to predict the binding between the free ligand with receptor of mutant human androgen (ARccr) derived from androgen‐independent prostate cancer (1GS4), crystal structure of yeast‐specific serine/threonine protein phosphatase (ppz1) of Candida Albicans (5JPE) and crystal structure of renal tumor suppressor protein, folliculin (3 V42) and to identify the binding mode and the crucial functional groups interacting with the three proteins.

SYNTHESIS, SPECTROSCOPIC, ANTIBACTERIAL AND ANTIOXIDANT ACTIVITIES OF Pd(II) COMPLEXES CONTAINING TRIDENTATE SCHIFF BASES

Pd(II) complexes of the form [PdLNH3] (where L = N-salicylidene-o-aminophenol (L1), N-(5-methoxysalicylidene-o-aminophenol) (L2) and N-(2-hydroxy-1-naphthalidene)-o-aminophenol) (L3) containing ammonia and ONO tridentate Schiff bases were synthesized. These complexes were characterized by elemental analysis, infrared, ultraviolet-visible, proton and carbon-13 spectroscopies. The NMR spectra showed that the Schiff bases coordinated to the palladium(II) ion through the two deprotonated phenolic oxygen and azomethine nitrogen atoms. The presence of ammonia molecules in these complexes were indicated by the IR and 1H NMR spectra. The spectral data suggested a square planar geometry for the complexes. The biological studies revealed that the complexes displayed better antibacterial and antioxidant activities than the parent Schiff bases.