Tridentate Schiff Base Ligand Research Articles

Synthesis, crystal structure, Hirshfeld surface analysis, DFT computations and protein binding efficiency of a 1-D Ni(II) chain derived from a tridentate Schiff base ligand

A new Ni(II)-azido 1-D coordination polymer, [Ni2L2(μ1,1-N3)(μ1,3-N3)]n, was obtained through reaction of 1-[(3-dimethylamino-propylimino)-methyl]-naphthalen-2-ol (HL) and the perchlorate salt of nickel(II) in the presence of pseudohalide azide. X-ray crystallography and spectroscopic experiments (IR and UV-Vis) were used to describe this coordination polymer (CP). Single crystal X-ray studies revealed that the CP is a one-dimensional chain of Ni(II) in which the neighboring dimeric units (triply bridged by di-μ2-phenoxidoand µ1,1-N3) are further connected by μ1,3-azido bridges in a zig-zag fashion. The cooperative participation of N···H hydrogen bonding, π···π stacking and C-H···π interactions occur during crystal packing. A 2-D supramolecular architecture with star-shaped voids results from additional C–H···π stacking interactions. Hirshfeld surface analysis was used to look at the intermolecular interactions. DFT studies were carried out to calculate the HOMO-LUMO band gap of the ligand as well as the coordination polymer. Interaction of the CP with bovine serum albumin (BSA) protein was investigated spectroscopically by absorption and fluorescence titration methods. The result showed that the CP could quench the intrinsic fluorescence of BSA. Fluorescence resonance energy transfer (FRET) studies revealed that energy transfer takes place from BSA to the CP. Cyclic voltammetry of the CP indicated an irreversible cathodic redox couple assigned to Ni(II)/Ni(I).

Synthesis, structural characterization, and theoretical analysis of novel zinc(ii) schiff base complexes with halogen and hydrogen bonding interactions.

In this article, we present the synthesis and characterization of three zinc(ii) complexes, [ZnII(HL1)2] (1), [ZnII(HL2)2]·2H2O (2) and [ZnII(HL3)2] (3), with three tridentate Schiff base ligands, H2L1, H2L2, and H2L3. The structures of the complexes were confirmed by single-crystal X-ray diffraction analysis. DFT calculations were performed to gain insights into the self-assembly of the complexes in their solid-state structures. Complex 1 exhibits dual halogen-bonding interactions (Br⋯Br and Br⋯O) in its solid-state structure, which have been thoroughly investigated through molecular electrostatic potential (MEP) surface calculations, alongside QTAIM and NCIPlot analyses. Furthermore, complex 2 features a fascinating hydrogen-bonding network involving lattice water molecules, which serves to link the [ZnII(HL2)2] units into a one-dimensional supramolecular polymer. This network has been meticulously examined using QTAIM and NCIplot analyses, allowing for an estimation of the hydrogen bond strengths. The significance of H-bonds and CH⋯π interactions in complex 3 was investigated, as these interactions are crucial for the formation of infinite 1D chains in the solid state.

Asymmetric tridentate Schiff base ligand based mononuclear Zn(II) and Hg(II) complexes: Synthesis, structure, spectroscopic studies, thermal studies, and DFT calculation

Two novel mononuclear metal(II) complexes with an asymmetric tridentate Schiff base ligand, and azide/chloride anions, namely [ZnL(N3)2] (1) and [HgL(Cl)2] (2) (L = (pyridin-2yl)methylimino)-2-ethylpyridine), have been synthesized and structurally characterized by elemental analysis, single crystal X-ray crystallography, FT-IR, NMR, UV–vis electronic absorption spectroscopic analysis. The metal in both the complexes displays a pentacoordination environment realized by the tridentate Schiff base and counter anions. The coordination geometry of Zn in complex 1 is in between a trigonal bipyramidal and square pyramidal, whereas Hg in complex 2 shows a distorted square pyramidal. Theoretical DFT/TD-DFT calculation data performed using B3LYP functional with LanL2MB basis set, compared with values of experimental measurements, have shown a reasonable accord. The thermal stability of both complexes has been studied.

Experimental and computational evaluation of anti-malarial and antioxidant potential of transition metal (II) complexes with tridentate schiff base derived from pyrrolopyrimidine.

In the twenty-first century, we are experiencing persistent waves of diverse pathogen variations, contributing significantly to global illness and death rates. Within this varied spectrum of illnesses, malaria and oxidative damage emerge as prominent obstacles that have persistently affected human health. The motivation for exploring the antioxidant potential of transition metal (II) complexes with tridentate Schiff base ligands is driven by the need for effective treatments against malaria and oxidative stress-related conditions. Both malaria and oxidative damage are significant global health concerns. Transition metal complexes can potentially offer enhanced anti-malarial and antioxidant activities, providing a dual benefit. To explore the aforementioned facts and examine the therapeutic potential, the previously synthesized pyrrolopyrimidinehydrazide-3-chlorobenzaldehyde, such as HPPHmCB ligand(1)andtheirMn(II),Fe(II),Co(II),Ni(II), Pd(II),Cu(II),Zn(II),Cd(II),Hg(II)complexes(2-10) of benzaldehydes and pyrrolopyrimidinehydrazide were proposed for in vitro anti-malarial and antioxidant investigation. These compounds were assessed for their anti-malarial efficacy against Plasmodium falciparum using a micro assay protocol, with IC50 values indicating the concentration required to inhibit parasite maturation by 50%. The Hg(II) complex displays pronounced antimalarial activity with an IC50 value of 1.98 ± 0.08µM, closely aligning with the efficacy of quinine, whereas Zn(II), Cu(II), Pd(II) complexes demonstrates most significant anti-malarial activity, with IC50 values close to the reference compound quinine. The antioxidant activity of the compounds was evaluated using the DPPH assay, with several metal complexes such as Cu(II)and Zn(II) showing strong potential in neutralizing oxidative stress. Furthermore, molecular docking simulations were conducted to explore the binding interactions of the compounds with PfNDH2, providing insights into their pharmacological potential. The study also examined the electronic properties, solubility, and potential hepatotoxicity of the compounds. The findings suggest that the metal complexes could be promising candidates for further development as anti-malarial agents, offering enhanced potency compared to the base compound.

The synthesis of Fe3O4@SiO2-NNO-CuII nanocatalyst and investigation of its application in the synthesis of imidazo[1,2-a]pyridines

In this study, a tridentate Schiff base ligand obtained from the condensation of salicylaldehyde and 3-amino-1,2,4 triazole was covalently immobilized on the surface of 3-chloro-trimethoxysilane-functionalized magnetic nanoparticles. This nitrogen and oxygen-rich compound provides donor arms for the coordination of copper ions. The prepared nanocatalyst (Fe3O4@SiO2-NNO-CuII) has been characterized by various techniques including FT-IR, EDX, SEM, VSM, XRD and ICP analysis and used as an efficient recyclable catalyst for the synthesis of imidazo[1,2-a]pydidines. Imidazo[1,2-a]pyridine products were obtained through the coupling reaction of substituted benzaldehydes, 2-aminopyridine derivatives and phenylacetylene under solvent-free conditions in high yields and short reaction times.

Structural Investigation of Schiff Base Ligand and Dinuclear Copper Complex: Synthesis, Crystal Structure, Computational, and Latent Fingerprint Analysis.

The structural studies of the fluorinated Schiff base ligand and its copper complex were synthesized and characterized by Fourier transform infrared, UV-visible, and photoluminescence spectroscopy. Single-crystal X-ray diffraction analysis unveils a dinuclear copper complex arising from double bridging acetate anions to copper ions that are chelated by the tridentate Schiff base ligand Cu(LS). The trigonality index τ5 of 0.080 indicates a distorted square pyramidal coordination geometry for the metal. The SL ligand and complex exhibit intra- and intermolecular interactions, leading to unique supramolecular architectures. The structural changes between the free halogenated Schiff base ligand and upon coordination with the metal were extensively studied by experimental and theoretical approaches. The intra- and intermolecular interactions have been analyzed by Hirshfeld surface and quantum theory of atoms in molecules analysis, and the enrichment ratio highlights the most favored interactions in the formation of molecular packing. The chemical and physical properties, such as the HOMO - LUMO energy gap, chemical reactivity, and electron density topology, are studied using density functional theory studies. In addition, the Schiff base ligand compound is used to study the latent fingerprint analysis.

Synthesis, characterization, and structural analysis of hetero Ni(II)–Na(I) and Homo Ni(II)–Ni(II) dinuclear complexes with a flexible tridendate schiff base ligand

Two different novel [Ni(II)–Na(I)]n and Ni(II)–Ni(II)] complexes have been synthesized successfully using a flexible tridentate Schiff base ligand. These complexes are characterized by IR and single crystal X–ray analysis and the optical properties of these complexes have been studied by UV spectroscopy (solution and solid). The [Ni(II)–Na(I)]n complexes are repeatedly connected with another Ni(II)–Na(I) unit to yield a linear polymeric chain. The Ni(II)–Ni(II) complex shows the nature of supramolecular dimeric cluster. These results are evidenced by x-ray structural analysis. Both as-obtained complexes are shown in different structures, such as hetro metal [Ni(II)–Na(I)]n] and homo metal [Ni(II)–Ni(II)]coordination environments with the same ligand. The first one forms a linear polymeric structure whereas the second one forms a cluster. The more intense band at 2104 cm1 is assigned to the NCS ligand of compound 1. A sharp band at 1068 cm1 together with a band at 625 cm1 in compound 2 is assigned to the ClO4 stretching vibrations and these bands are evidence for the presence of ionic perchlorate (non–coordinated). The electronic spectra of compounds 1 and 2 are recorded in ACN solvent to exhibit a broad peak around 380 nm due to d-d transition.

Synthesis, characterization, biomolecule-binding and preliminary anticancer properties of PtCl(N^N^O) with naphthalenyl-containing tridentate ligand

A tridentate Schiff base ligand was synthesized via the reaction of 2-hydroxynpthaldehyd with N-phenyl-o-phenylenediamine. The obtained ligand was utilized in synthesizing Pt-L2 [PtCl(N^N^O)]. The ligand and Pt-L2 were characterized by IR, NMR and mass spectroscopies as well as elemental analysis. The DNA-binding of Pt-L2 was examined by fluorescence quenching using the EB-DNA adduct method. The apparent affinity for the compound toward ct-DNA was nearly twice the affinity of ethidium bromide. Changes in the relative viscosity induced by platinum complexes of ct-DNA indicated an intercalation mode of binding for Pt-L2 and covalent binding for the second platinum compound, Pt-L1, synthesized from 3-ethoxysalicyaldehyde and N-phenyl-o-phenylenediamine. BSA-binding by Pt-L2 indicated the spontaneous formation of an adduct with the protein with good binding affinity (7.7 × 104). The anticancer activities of Pt-L2 were evaluated against two cancer cell lines and compared to that of Pt-L1 and cisplatin. Pt-L2 has better IC50 values, possibly because of its highly π-delocalized planar system. Moreover, selectivity index for Pt-L2 is high (SI = 168) which is one of the criteria for potential chemotherapeutic agents (higher than that observed for cisplatin (SI = 37)).

Synthesis, spectro-themal characterization, DFT calculations and biochemical evaluation of a newly synthesized tridentate Schiff base transition metal complexes

An appropriate conventional method has been utilised to synthesie new tridentate Schiff base ligand 4-chloro-2-((2,4-dihydroxybenzylidene)amino)benzoic acid with Co (II), Ni (II), Cu (II), and Zn (II) complexes. Several spectroscopic(FT-IR, 1H NMR, 13C NMR, UV–Vis, Mass), TGA-DTA, powder X-ray diffraction, and DFT calculations, were used to characterise these complexes. According to these spectroscopic investigations, the ligand coordinated with the metals via carboxylic oxygen, azomethine nitrogen, and hydroxyl oxygen, acting as a tridentate ligand. Appropriate geometry for every complex has been proposed based on spectroscopic and analytical data. In tetrahedral geometry with Co(II), Ni(II), Zn(II), and square planner with Cu(II) ion, the ligand functions as a tridentate via ONO donors. The optimal structure (bond length and bond angle) and chemical reactivity of the ligand and its metal complexes from their Frontier Molecular Orbitals (FMO) and Molecular electrostatic potential (MESP) calculations have been investigated using Density Functional Theory (DFT/B3LYP,6-31G**/6-311G**(d,p), and LanL2DZ basis sets) calculations. In vitro DPPH radical scavenging techniques were used to assess the antioxidant activity of the ligand and its metal complexes. The results indicated that all of the complexes exhibited good antioxidant activity, with the Cu (II) complex being the most potent with the lowest IC50 values. The ligand and complexes in vitro antibacterial activities were further explored by screening them against Gram(+ve) bacteria (Bacillus subtilis) and Gram(−ve) bacteria (E. coli). Significant activity was demonstrated by all synthesised compounds against the tested strains of bacteria. The antifungal activity of complexes against Aspergillus niger and Candida albicans was determined. The results indicated that Cu(II) complex exhibited good antifungal activity against Candida albicans, but not against Aspergillus niger. The fungal strain Aspergillus niger was not significantly inhibited by complexes. The complexes have greater antimicrobial activity than the Schiff base ligand, as indicated by the MIC values.

New penta-Coordinated Cadmium(II) Complexes: Synthesis, Characterization, Thermal, Antimicrobial, Antioxidant and Cytotoxicity Properties.

In this paper, a new tridentate Schiff base ligand (L) with nitrogen donor atoms and its cadmium(II) complexes with the general formula of CdLX2 (X=Cl-, Br-, I-, SCN-, N3 -, NO3 -) have been synthesized and characterized by physical and spectral (FT/IR, UV-Vis, Mass, and 1H, 13C NMR spectroscopies) methods. Also nano-structured cadmium chloride and bromide complexes were synthesized by sonochemical method and then used to prepare nanostructured cadmium oxide confirmed by XRD and SEM techniques. Thermal behavior of the compounds was studied in the temperature range of 25 to 900 °C under N2 atmosphere at a heating rate of 20 °C/ min. Moreover, thermo-kinetic activation parameters of thermal decomposition steps were calculated according to the Coats-Redfern relationship. Antimicrobial activities of the synthesized compounds against two gram-positive and two gram-negative bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and two fungi of Candida albicans and Aspergillus niger were investigated by well diffusion method. SEM technique was used to monitor the morphological changes of the bacteria treated with the compounds. The 2,2-Diphenyl-1-picrylhydrazyl(DPPH) and the ferric reducing antioxidant power (FRAP) methods were used to evaluate the antioxidant ability of the ligand and its cadmium(II) complexes. In final, the cytotoxicity properties of the ligand and some cadmium(II) complexes against PC3 cancer cells were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) bioassay and nitric oxide (NO) level measurement. The morphological changes of prostate cancer (PC3) cells due to treatment with the ligand and its complexes confirmed their anticancer effectiveness.

Synthesis, theoretical analysis, and biological properties of a novel tridentate Schiff base palladium (II) complex.

Schiff base complexes play a crucial role in bioinorganic chemistry. A novel curcumin/phenylalanine tridentate Schiff base ligand and its palladium (II) complex were synthesized so that they were stable in aqueous buffer. The structure of the complex was investigated using a variety of methods, including DFT, NBO analysis, FMOs, and MESP. The interaction of the complex with a plasmid (pUC19) and CT-DNA was studied. The anticancer, antibacterial, and antioxidant activities of the complex were examined. The statistical analysis of the MTT assay was compared using the 1-way ANOVA and Tukey test. Results showed that the complexes were stable in aqueous buffer, pH 8. The extrinsic fluorescence emission of the plasmid and CT-DNA was quenched while interacting with the complex. The complex had an IC50 of 72.47 µM against MCF-7 cells. The ANOVA and Tukey analysis of MTT data demonstrated a statistically significant difference between groups (P < 0.0001). The minimum inhibitory concentrations (MIC) of the complex for E. coli and S. aureus were 300 and 200µg/mL, with 96.3 and 95.2% biofilm growth inhibition at 250µg/mL, respectively. The sample concentrations contributing to 50% radical inhibition in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) test for curcumin, ligand, and palladium (II) complex were 33.62, 21.27, and 51.26 µM, respectively. The results suggest that the complex interaction with DNA is one of the potential mechanisms for eliminating cancer cells and bacteria in the planktonic and biofilm. On the other hand, while stability in an aqueous buffer at pH 8 increases, the modified curcumin antioxidant effect decreases.

Acceptorless dehydrogenation of ethanol by Ru(II) complexes with tridentate Schiff-base ligands

Hydrogen, often hailed as the purest form of energy, is renowned worldwide for its exceptional energy density, renewability, and pivotal role in driving sustainable societal progress. However, safe, efficient, and cost-effective storage of hydrogen remains a significant challenge. Ethanol, as a liquid organic hydrogen carrier (LOHC), offers a notable solution with its high hydrogen content, eco-friendliness, and cost efficiency. In this work, hydrogen production by acceptorless dehydrogenation of ethanol (ADE) catalyzed by two new Ru(II) complexes (C1 and C2) with Schiff-base ligands was explored. Under optimized conditions, these catalysts produced respectable turnover numbers (TONs) of 19,398 and 31,965, respectively, comparing favorably with other homogeneous catalysts in the same capacity. Notably, the hydrogen gas produced is free of any CO, which is critical for the hydrogen-based fuel-cell application. Ethyl acetate, the byproduct of this process, can be recycled for other purposes. A mechanism possibly responsible for the observed catalysis was proposed based on an intermediate identified by the mass spectroscopic analysis of the reaction mixture.

An Ammonium Cation Included Dinuclear Cd(II) Complex and A Face-Shared Octahedral Dinuclear Cd(II) Complex with N2O Donor Tridentate Schiff base Ligand

One face-shared octahedral Cd(II) complex and one ammonium cation included Cd(II) complex have been examined with the N2O donor monoanionic Schiff-base ligand 4-methyl-2,6-bis(((phenylmethyl)imino)methyl)phenol (HL) having a central phenoxide unit. The configuration of the cadmium coordination geometries is responsible for varying modes of ligand binding and structures. The gas phase geometry of complex 1 has been optimized by density functional theory. In CH3OH, the reaction between HL and Cd(NO3)2·4H2O in the presence of triethylamine produces a tris-L clipped face-shared octahedral dinuclear complex [Cd2(μ-L)3]·(OH) (1). Use of Cd(NO3)2·4H2O and NH4SCN in CH3OH in the absence of triethylamine leads to the synthesis of [Cd2(μ-L)2(μ1,1-NCS)(μ-NH4 +)(NCS)2] (2), which contains a NH4 + cation at its center. Changes in co-ligands have an ability to regulate the synthesis of these two Cd(II) complexes, effectively allowing selfassembly to be directed. Three types of bridges of Cd(OPh)3Cd and Cd(OPh)2(μ1,1-NCS)(μ- H4+)Cd in 1 and 2 are responsible for the Cd···Cd separations of 3.324 and 3.432 Å, respectively.

Synthesis, Structural Characterisation and Biological Activity; New Metal Complexes Derived from Semicarbazone Ligand

The results of synthesizing a novel tridentate Schiff-base ligand and its metal complexes have been given. The ligand itself is described as being tridentate. The synthesis of the ligand has the following chemical formula: (E)-2-((2S)-4-(tert-butyl) -2-((S)-(phenylamino) (p-tolyl) methyl) cyclohexylidene) hydrazine -1-carboxamide was produced as a byproduct of the reaction between benzoic acid and benzoic acid between (((4-(tert-butyl)-2-((S)-(phenylamino)(p-to and (HL). The ligand was reacted with 1:1 (L:M) mole ratios of ions containing Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), which resulted in the production of title complexes. In cases where it was necessary, physicochemical techniques were utilized to characterize both the ligand and the complexes. Examples include magnetic susceptibility and conductance measurements, microanalysis of elements, nuclear magnetic resonance (1H, 13C), mass spectrometry, Fourier transform infrared (FT-IR), electronic spectra, and more. The results of these studies demonstrated that the ions Mn (II), Co (II), Cu(II), Ni(II), Zn(II), and Cd(II) can be partitioned into four-coordinate and six-coordinate complexes, respectively. In addition, the TGA was used to investigate whether or not the ligand and specific complexes were thermally stable. Several different bacterial and fungus strains were utilized to examine the ligand and its complexes for potential antibacterial activity. According to the findings, the complexes are far more effective than the free ligand in combating a wider variety of species. Keywords: Structural study; Metal complexes; Mannich -β-amino carbonyl; Thermal stability; Staphylococcus aureus (G+).

Synthesis, characterization, crystal structure, thermal and redox behaviour and antiproliferative studies of morpholine‐based two copper(II) compounds

Two novel copper(II) complexes, [Cu(L)(Cl)2](H2O) (1) and [Cu(L)(N3)2] (2), have been synthesized from a morpholine‐based N,N,N donor tridentate Schiff base ligand, (E)‐N‐(2‐morpholinoethyl)‐1‐phenyl‐1‐(pyridin‐2‐yl)methanimine (L). Ligand (L) and its stabilized complexes, 1 and 2, have been comprehensively characterized by different physical and spectroscopic techniques. Solid‐state single‐crystal X‐ray structures of both 1 and 2 have been determined. Powder X‐ray diffraction studies on the bulk samples of 1 and 2 have been executed to demonstrate that the synthesized bulk materials retain their solid‐phase purity as that exists in the single crystals. Cyclic voltammetric experiments have been done to demonstrate the redox behaviour of 1 and 2. UV–vis spectra of the copper(II) complexes with variation in time were accrued to probe that both 1 and 2 retain their stability in solution. Thermogravimetric analysis (TGA) has been performed to collate the thermal stability of 1 along with its possible thermal degradation behaviour. Room temperature magnetic moments of 1 and 2 have been determined. Cytotoxic activity of 1 and 2 has been screened against non‐small human lung cancer cell, A549.

Synthesis, Structures and Photophysical Properties of Tetra- and Hexanuclear Zinc Complexes Supported by Tridentate Schiff Base Ligands

The synthesis, structure and photophysical properties of two polynuclear zinc complexes, namely [Zn6L2(µ3-OH)2(OAc)8] (1) and [Zn4L4(µ2-OH)2](ClO4)2 (2), supported by tridentate Schiff base ligand 2,6-bis((N-benzyl)iminomethyl)-4-tert-butylphenol (HL) are presented. The synthesized compounds were investigated using ESI-MS, IR, NMR, UV-vis absorption spectroscopy, photoluminescence spectroscopy and single-crystal X-ray crystallography. The hexanuclear neutral complex 1 comprises six-, five- and four-coordinated Zn2+ ions coordinated by O and N atoms from the supporting ligand and OH- and acetate ligands. The Zn2+ ions in complex cation [Zn4L4(µ2-OH)2]2+ of 2 are all five-coordinated. The complexation of ligand HL by Zn2+ ions leads to a six-fold increase in the intensity and a large blue shift of the ligand-based 1(π-π)* emission. Other biologically relevant ions, i.e., Na+, K+, Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+ and Cu2+, did not give rise to a fluorescence enhancement.

Synthesis, characterization, photocatalytic activity, DNA interaction and antimicrobial studies of some lanthanide(III) complexes with a tridentate Schiff base ligand

Lanthanide complexes of Sm(III), Nd(III), and Dy(III) with a Schiff base ligand, (potassium2-((4-hydroxy-3-methoxybenzylidene)amino)acetate, derived from condensation of 4-hydroxy-3-methoxybenzaldehyde and 2-aminoethanoic acid were synthesized. The compounds were characterized by elemental analysis, IR, UV–Vis, 1H-NMR, ESI-MS, photoluminescence spectra, thermogravimetric analysis, magnetic susceptibility, and molar conductivity measurements. No well-defined peaks were observed in X-ray diffractograms of the synthesized complexes, indicating an amorphous nature. The Schiff base ligand is tridentate and coordinated with the metal ion through phenolic oxygen, azomethine nitrogen, and carboxylic oxygen. Thermal properties of the metal complexes were studied using thermogravimetric analysis (TG/DTG) and revealed good thermal stability. The photocatalytic efficiencies of the complexes were explored using solar water-splitting. The optical band gaps (E g) were measured and found to be 2.94, 2.86, and 2.82 eV for Sm(III), Nd(III), and Dy(III) complexes, respectively. These values indicated the semi-conducting nature of the investigated complexes. At room temperature, samarium and dysprosium complexes showed characteristic luminescence of the central metal ions ascribed to the efficient transfer of energy from the Schiff base ligand to the metal center under excitation at 390 nm. The binding properties of these complexes with calf-thymus DNA (CT-DNA) have been investigated using absorption spectrophotometry and fluorescence studies. The physicochemical properties such as hydrodynamic size, zeta potential, and stability of the DNA/complexes were also investigated. DNA cleavage activities of the compounds were assayed using the Agarose gel electrophoresis method. In-vitro antimicrobial activities of the compounds were screened against selected pathogenic strains by Agar well diffusion method.

A study of in vitro antimicrobial activities and antioxidant of lanthanide complexes with a tri dentate Schiff base ligand

The tridentate N3-type Schiff base 4-(anthracen-10-yl)-2,6-di(pyridin-2-yl)pyridine was synthesized from the condensation reaction of 2-acetyl pyridine and anthracene-10-carbaldehyde with ammonia using one pot methodology. This hybrid ligand was used for synthesis of lanthanide complexes (La, Sm and Eu) as novel potential biological agent. The lanthanide complexes were characterized on the basis of elemental, FT-IR, UV-Visible, mass spectrometry as well as molar conductivity. The complexes were screened for in vitro antibacterial and antifungal activities against the multidrug resistant pathogens such as Escherichia coli, Staphylococcus aureus and Aspergillus niger. The antimicrobial results revealed that Sm+3 complex has a good potency against different gram positive and gram negative bacteria in comparison with other complexes. All lanthanide complexes showed a moderate antioxidant activity with IC50. The DPPH· radical scavenging effects of the Schiff base ligand and its Ln (III) complexes were screened. The Ln (III) complexes were significantly more efficient in quenching DPPH· than the free Schiff base ligand.

Design, spectroscopic characterization, DFT, molecular docking, and different applications: Anti-corrosion and antioxidant of novel metal complexes derived from ofloxacin-based Schiff base

A new tridentate Schiff base ligand derived from ofloxacin (oflo) with 2-aminophenol was synthesized and a series of d-transition metal complexes were prepared. The ligand and its metal complexes were investigated using elemental, spectral, and thermal studies. The molecular and electronic structure of the free ligand and its Zn(II) complex were refined theoretically, and the chemical quantum parameters were computed. SEM studies were conducted on the free ligand and its Ni(II) chelate to confirm their nanostructure. The anti-corrosive performance of HL for mild steel (MS) was employed using electrochemical frequency modulation (EFM), potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) and showed a significant efficiency as anticorrosion agent (89.71%). Molecular docking studies were carried out between the ligand and its [Zn(HL)(H2O)Cl2] complex with active sites of 3T88, 3Q8U, and 3Q7K receptors and the complex showed the strongest binding with 3T88 receptor (-31.9 kcal mol−1). The antioxidant activity of the free ligand and its metal chelates had been carried out using the standard DPPH method and the free ligand showed the highest antioxidant activity (IC50 = 10.52 µg/mL). The in vitro antibacterial activity showed that all prepared compounds were biologically active and Fe(III) complex has the highest inhibiting activity against Proteus Vulgaris Gram-negative bacteria.

Ru(II) complexes containing NOO donors of tridentate Schiff base ligands: Synthesis, characterization, crystal structure and catalytic activity in transfer hydrogenation of ketones

A new series of pincer type ruthenium(II) Schiff base complexes namely [Ru(CO)(PPh3)2(L1‒6)] (1–6) (where, L1‒6 ​= ​NOO ‒ donors of tri-dentate ligands) have been synthesized from ruthenium precursor such as [RuHCl(CO)(PPh3)3] containing tri-dentate Schiff bases ligands (H2L1‒H2L6). These ruthenium complexes were analyzed by elemental analysis and diverse characterizations such as FT‒IR, UV–Vis and NMR (1H and 31P) spectroscopy studies. The crystal structure of one of the complexes 5 ([Ru(CO)(PPh3)2L5]) was determined by single crystal X‒ray crystallography that revealed pincer type of coordination mode of complexes. Furthermore, complexes 1–6 have been utilized for transfer hydrogenation of aromatic ketones to secondary alcohols in the presence of i‒PrOH/KOH. The catalytic efficiency of complexes showed an efficient for transfer hydrogenation of ketones with alcohol as moderate to high conversions.