Design and nonlinear optical properties (NLO) using DFT approach of new Cr(III), VO(II), and Ni(II) chelates incorporating tri-dentate imine ligand for DNA interaction, antimicrobial, anticancer activities and molecular docking studies

Synthesis and characterization of nano crystallite carboxamide-based iron(III) complexes: SOD mimetic activity, antibacterial and anticancer activity and molecular docking study

Three carboxamide-based ligands and their iron(III) complexes were prepared and structurally characterized. Analytical, thermal and mass spectra measurements showed a 1:1 stoichiometric (M:L) of the synthesized iron(III) complexes. The distorted octahedral geometry of the present iron(III) complexes was assigned based on the results of spectroscopy and magnetometry. Processing of X-ray diffraction data for powder samples by the software Expo 2014 confirmed the octahedral geometry of the three iron(III) complexes. Electrochemical properties of the present iron(III) complexes were studied by cyclic voltammetric measurements. The present iron(III) complexes exhibit SOD like activity with IC50 values of 16.45, 15.24 and 9.70 μM. The drive forces (-λ or ΔG°) controlling these biocatalytic reactions were determined and correlated with catalytic activity. The proposed catalytic mechanistic implications for the conversion of O2•- to H2O2 and H2O were discussed. The antimicrobial activity has been studied in vitro against G(+) and G(-) pathogenic bacteria. The in vitro anticancer activity of the carboxamide-based ligands and their iron(III) complexes against human Hepatocellular carcinoma (HepG-2) cell lines was examined. The obtained results demonstrated the potent anticancer activity of iron(III) complexes with increased safety on normal cells compared to cisplatin. Molecular docking calculations confirmed the experimental findings of the antibacterial and anticancer activities of both free ligands and their iron(III) chelates.Communicated by Ramaswamy H. Sarma.

Comparative Linkage of Novel Anti-Tumor Pd(II) Complex with Bio-Macromulecules: Fluorescence, UV-Vis, DFT, Molecular Docking and Molecular Dynamics Simulation Studies

A novel mononuclear palladium complex, [Pd(dach)(SSA)], where dach and SSA are diaminocyclohexane and sulfosalicylic acid ligands, respectively, has been synthesized and identified utilizing analytical and spectral methods. DFT calculations, namely geometry optimization, MEP, HOMO-LUMO and NBO analysis, have been conducted at B3LYP level by aug-ccpVTZ-PP and 6-311G(d, p) basis sets. NBO and HOMO-LUMO analysis exhibited that the palladium compound is stable. MEP showed the potential sites of molecule for the interaction. By employing MTT assay, the cytotoxicity activity of the aforesaid compound was examined on K562 cell line, which revealed a proper activity compared to cisplatin. To ascertain the lipophilicity of the newly made compound, the partition coefficient measurement was accomplished, which follows the order of cisplatin < Pd(II) complex. Next, investigation of binding properties of the studied compound with DNA of calf thymus and BSA were done by spectroscopic (CD, fluorescence emission and electronic adsorption) and non-spectroscopic (viscosity measurements, DNA gel electrophoresis, molecular docking and molecular dynamics simulation) methods. The outcomes of CD and UV-Vis spectroscopy demonstrated that the title compound refolded the protein via increasing the alpha helix percentage. The data obtained from UV-Vis studies indicated the non-intercalative mutual action between Pd(II) complex with DNA. It also revealed that the Kapp magnitude of CT-DNA (7.43 × 104 M- 1) is higher than the BSA (5.17 × 103 M- 1), and L1/2 (midpoint of transition) of CT-DNA (5 µM) is lower than the BSA (5.7 µM), indicating that the complex has a greater binding affinity to CT-DNA than BSA. Fluorescence quenching mechanism of the two biomolecules by the metal complex is static and the calculated thermodynamic parameters (ΔS° < 0 and ΔH° < 0) suggested the hydrogen bonding and/ or van der Waals forces with DNA and BSA. Further, molecular docking indicated that the studied compound fits into the groove of DNA and the site I of BSA. The stability of metal compound-DNA/-BSA in the presence of H2O solvent and over the time were validated via molecular dynamics simulation.

Synthesis, characterization, molecular modeling studies, and biological evaluation of metal piroxicam complexes (M = Ni(II), Pt(IV), Pd(II), Ag(I)) as antibacterial and anticancer agents

Four piroxicam metal complexes; NiL2 , PtL2 , PdL2 , and AgL were synthesized and characterized by different techniques with enhanced antibacterial and anticancer activity. Regarding in vitro antimicrobial activity, complex NiL2 displayed potent antibacterial effect against Escherichia coli and Pseudomonas aeruginosa that was 1.9-folds higher than piroxicam (minimum inhibitory concentration [MIC] = 31.85, 65.32 µM), respectively. In case of G+ve bacteria, complex PtL2 had potent activity on Staphylococcus aureus which was 2.1-folds higher than piroxicam (MIC = 43.12 µM), while activity of complex AgL against Enterococcus faecalis was threefolds higher than piroxicam (MIC = 74.57 µM. Complexes PtL2 and PdL2 exhibited higher inhibition of DNA gyrase than piroxicam (IC50  = 6.21 µM) in the range of 1.9-1.7-folds. The in vitro antiproliferative activity depicted that all investigated complexes showed better cytotoxic effect than piroxicam, specifically Pt and Pd complexes which had lower IC50 values than piroxicam on human liver cancer cell line HepG2 by 1.8 and 1.7-folds, respectively. While Pd and Ag complexes showed 2 and 1.6-folds better effect on human colon cancer cell line HT-29 compared with piroxicam. Molecular modeling studies including docking on Stranded DNA Duplex (1juu) and DNA gyrase enzyme (1kzn) that gave good insight about interaction of complexes with target molecules, calculation of electrostatic potential map and global reactivity descriptors were performed.

Syntheses and characterization of novel antimony (III) and bismuth (III) derivatives containing β-enamino ester along with antimicrobial evaluation, DFT calculation, and cytotoxic study

Four novel antimony (III) and bismuth(III) complexes of the kind Cl-Sb-O-C(OR)-CH(CH3 )C-NH-(CH2 )2 -NH-C(CH3 )CH:C(OR)-O [where R = -CH3 , M = Sb (1a); R = -C2 H5 , M = Sb (1b); R = -CH3, M = Bi (1c); R = -C2 H5 , M = Bi (1d)] were successfully prepared by reacting antimony(III)chloride and bismuth(III)chloride with sodium salt of β-enamino esters in 1:1 stoichiometry, which were further structurally characterized by physicochemical and IR, 1 H, 13 C NMR spectral and mass spectrometry. Structural analysis revealed that all four derivatives of both antimony and bismuth display octahedarl geometry which has been optimized through computational studies. These derivatives along with their parent ligands were subsequently assayed in vitro for antibacterial (Bacillus subtilis, Pseudomonas aeruginosa) and antifungal (Aspergillus niger and Candida albicans) activities. Synthesized complexes were more efficacious in terms of biological activities as compared to parent ligands Further synthesized compounds were evaluated for their in vitro cytotoxic activity against lung cancer cell line A549 using MTT method. IC50 value for all four complexes was determined and all of them are found active. Computational studies of the representative complexes have been done using B3LYP/631-G* basis sets to provide optimized geometry.

Cobalt oxide-chitosan based nanocomposites: Synthesis, characterization and their potential pharmaceutical applications

This research aimed to prepare, characterize, and investigate the biological efficacy of chitosan‑cobalt (II) oxide hybrid nanocomposites against a variety of micrograms. Analytical methods, FTIR, SEM, XRD, and EDX, were utilized to thoroughly characterize the produced CS-CoO nanocomposite. In FTIR spectra, the presence of the chitosan peaks in addition to that of CoO at 681 and 558 cm-1 confirmed that CoO molecules interact with the chitosan backbone. Moreover, in the XRD measurements, significantly less chitosan crystallinity was observed. Due to the incorporation of a larger amount of cobalt oxide within the polymer matrix. Applying the Debye-Sherrer calculation, the crystallite size was obviously reduced from 48.24 nm (5 wt %) to 19.27 nm (20 wt %) for the obtained nanocomposites. Furthermore, SEM measurements showed a transformation in the chitosan surface with the physical adsorption of CoO molecules on the surface active sites of chitosan that were visible in SEM graphs. Additionally, EDX determined the amount of Co element within the chitosan, with the sample of 20 wt % weight being found to be 19.26 wt %. The variable dose well-diffusion method was utilized to assess the efficacy of the CS-Co nanocomposite against a wide range of bacteria and fungi. CS - CoO nanocomposite is more effective than chitosan alone as an antibacterial agent against both Gram-positive and Gram-negative bacteria. Moreover, the MTT approach was employed to measure the cytotoxicity based on the cell viability of different cancer cell lines under different UV expositions. The proportion of the destroyed cells elevated due to the easy diffusion of CS - CoO nanocomposite into cancer cells as UV-free anticancer activity. UV exposition has stimulated the anticancer activity, which was attributed to an increase in ROS generation caused by the increased dose of the chitosan and its CS - CoO nanocomposites. Furthermore, the antioxidant capacities of the prepared nano-composites thin films were validated using the DPPH free radical scavenging method and showed good antioxidant activities with the DPPH radical compared with standard vitamin C. It has been noticed that by increasing the content of CoO nanoparticles from 5 to 20 wt %, the biological activity of the prepared nanocomposites was enhanced.

Design, spectral characterization, quantum chemical investigation, biological activity of nano-sized transition metal complexes of tridentate 3-mercapto-4H-1,2,4-triazol-4-yl-aminomethylphenol Schiff base ligand

A tridentate Schiff base ligand, H2MTIP, was produced by condensing salicylaldehyde with 4-amino-4H-1,2,4-triazole-3-thiol. The ligand was then used to create nanosized complexes of Pt(II), Ni(II), Cu(II), and Pd(II). The complexes have the composition [Pt/Ni/Cu/or Pd(MTIP)(H2O)], this conclusion is supported by molar conductance, magnetic moments, elemental analyses, spectral analyses. In DFT analysis, the 6-31+ g(d,p) basis set was used to fully optimize the energy with respect to the shapes of Schiff base ligand and metal complexes. Pt(II), Ni(II), Cu(II), and Pd(II) complexes have been assigned square-planar geometries. At the same time, the intense diffraction peaks in X-ray diffractograms show their crystalline features with particle sizes in the nanoscale range. The binding interaction of calf thymus DNA with these metal complexes and their insulin-like activity was examined in vitro by inhibiting α-amylase. The study investigated the in-vitro activity of several complexes and identified Pt(II) complex as the one with the highest activity. The researchers then tested this complex for in-vivo antidiabetic activity in induced diabetic rats using the STZ model, and it significantly lowered blood glucose levels. The antioxidant activity and toxicity level of Pt(II) complex were also excellent, suggesting that it could be a good candidate for further research as a possible diabetes drug.Communicated by Ramaswamy H. Sarma.

Spectroscopic and theoretical approach of DNA interaction and anticancer studies of bio-pharmaceutically active pyrimidine derived Cu(II) and Zn(II) complexes

New metal(II) complexes (CuL2 and ZnL2) with pyrimidine appended Schiff base ligand (HL) were synthesized and characterized by diverse spectroscopic methods, reveals the proposed structure of metal(II) complexes possess square planar geometry. DNA interaction ability of isolated compounds was studied by UV-Visible, fluorescence, viscometric and electrochemical methods and the results showed that isolated compounds intercalated with calf thymus DNA (CT-DNA). In addition, anticancer activities of HL, CuL2, and ZnL2 have been evaluated by MTT assay, signifying moderate cytotoxic activity on selected cancer cell lines and less toxicity on NHDF normal cell line due to the specific targeting of pyrimidine analogues. Moreover, antioxidant activities of isolated compounds towards diverse free radicals have been studied by spectrophotometric methods. These results showed that CuL2 has better antioxidant ability than HL and ZnL2. Finally, antimicrobial activities of isolated compounds against selected antimicrobial pathogens exposed that CuL2 has better antimicrobial activity on E. coli and C. albicans than other antimicrobial pathogens. The DFT calculations have been done to get the optimized geometry of the ligand and the metal complexes. In order to get a broad understanding of the interactions of these synthesized metal complexes, a detailed molecular docking analysis is taken up.

Synthesis, crystal structure, spectroscopic and computational investigations of the newly synthesized Schiff bases scaffold as enzyme inhibitor

The current project was planned to access the enzyme inhibition potential of the synthesize imines; (E)-2-(2-hydroxy-4,5-dimethoxybenzylideneamino)benzonitrile 1 and (E)-2-(((3-hydroxy-4-methylphenyl)imino)methyl)-4-methoxyphenol 2 by the reported protocol of our continuous research and also assess their theoretical function in term of in silico action. The structural characterization of imines was done through advanced techniques i.e., FTIR, ¹H NMR, ¹³C NMR, and UV spectroscopy. Moreover, a single X-Ray diffraction technique (SCXRD) was employed for real structural identification of imines dimensions, which revealed that compound 1 has a triclinic crystal system although 2 has a monoclinic one. A 2D fingerprint plot and Hirshfeld surface analysis (HS) was employed in the crystalline assembly of compounds to check intermolecular contacts and also their degree of contributions. Both compounds were optimized by B3LYP functional mode using a certain basis set (6-31G). The practical data (XRD) and theoretical data (DFT) of both molecules were compared and found between a sound coherence. Molecular docking studies in term of in silico assessment were conducted against enzymes of the esterase and alpha-glucosidase family. The docking outputs give a forecast about compounds that could be employed as protein inhibitors against analyzed protein surfaces.

Design, Synthesis, Spectroscopic Inspection, DFT and Molecular Docking Study of Metal Chelates Incorporating Azo Dye Ligand for Biological Evaluation

A new heterocyclic azo dye ligand (L) was synthesized by the combination of 4-amino antipyrine with 4-aminophenol. The new Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) complexes were synthesized in excellent yields. The metal chelate structures were elucidated using elemental analyses, FT-IR, ¹H-NMR, mass, magnetic moment, diffused reflectance spectral and thermal analysis (TG-DTG), and molar conductivity measurement. According to the FT-IR study, the azo dye ligand exhibited neutral tri-dentate behavior, binding to the metal ions with the azo N, carbonyl O, and protonated phenolic OH. The ¹H-NMR spectral study of the Zn(II) complex supported the coordination of the zo dye ligand without proton displacement of the phenolic OH. Diffused reflectance and magnetic moment studies revealed the octahedral geometry of the complexes, as well as their good electrolytic nature, excepting the Zn(II) and Cd(II) complexes, which were nonelectrolytes, as deduced from the molar conductivity study. The theoretical calculations of optimized HOMO-LUMO energies, geometrical parameters, electronic spectra, natural atomic charges, 3D-plots of MEP, and vibrational wavenumbers were computed and elucidated using LANL2DZ and 6-311G (d, p) basis sets of density functional theory (DFT) with the approach of B3LYP DFT and TD-DFT methods. The ligand and complexes have been assayed for their antimicrobial activity and compared with the standard drugs. Most of the complexes have manifested excellent antimicrobial activity against various microbial strains. A molecular docking investigation was also performed, to acquire more information about the binding mode and energy of the ligand and its metal complexes to the Escherichia coli receptor using molecular docking. Altogether, the newly created ligand and complexes showed positive antibacterial effects and are worth future study.

Development of New Azomethine Metal Chelates Derived from Isatin: DFT and Pharmaceutical Studies

Through the condensation of isatin (indoline-2, 3-dione) and aniline in a 1:1 ratio, a Schiff base ligand was synthesized and characterized via (¹H-NMR, mass, IR, UV-Vis) spectra. Elemental analyses, spectroscopy (¹H-NMR, mass, UV-Vis), magnetic susceptibility, molar conductivity, mass spectra, scanning electron microscope (SEM), and thermal analysis have all been used to characterize a series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) metal complexes derived from the titled ligand. The metal-to-ligand ratio is 1:1, according to the analytical data. The Schiff base ligand displayed bidentate behavior with NO coordination sites when it bonded to metal ions, as seen by the IR spectra. The magnetic moment measurement and UV-Vis spectral investigation showed the octahedral geometry of the Cr(III), Fe(III), Co(II), Ni(II), and Zn(II) complexes, whereas they suggested the tetrahedral geometry of the Mn(II), Cu(II), and Cd(II) complexes. The thermal analysis study confirmed the presence of both hydrated and coordinated water molecules in all the compounds, except for the Mn(II) complex, and showed that the complexes decomposed in three or five decomposition steps leaving the corresponding metal oxide as a residue. The ligand and its metal complexes' antibacterial efficacy were evaluated. The findings showed that the metal complexes had stronger antibacterial properties than the ligand alone. The ligand and its metal complexes' anticancer properties were also investigated. A DFT investigation is also reported to gather information regarding the electronic features of the ligand and its metal complexes. Finally, drug-likeness and ADME characteristics were also calculated as parameters.

Two state "ON-OFF" NLO switch based on coordination complexes of iron and cobalt containing isomeric ligand: a DFT study

Coordination complexes are interesting materials for nonlinear optical (NLO) applications due to their large hyperpolarizability values. Moreover, switchable NLO response is also important in coordination complexes. Herein, we report two state ON-OFF switchable NLO contrast of coordination complexes of Fe and Co containing isomeric ligands. The optical, UV-visible, and electronic properties besides the "ON-OFF" switching effect are calculated using the CAM-B3LYP/6-31+G (d) method. The NLO responses of ligand-metal isomers are qualitatively evaluated through variation in charge transference (CT) style through TD-DFT. The higher β o in each isomeric pair is strongly dependent on the HOMO-LUMO gap. The isomer 4b with lowest HOMO-LUMO gap shows the highest NLO response. The charge transfer pattern in these complexes results in variation of their β o values. The notable β o contrast of 21.15 in isomeric pairs 3a and 3b makes these complexes a favorable material for genuine NLO switches. Hence, the outcome of the current investigation reveals that these ligand-metal isomeric complexes exhibit a two-state switch "ON-OFF" effect.

Cytotoxic effects of Pd(II) complexes on cancer and normal cells: Their DNA & BSA adduct formation and theoretical approaches

Herein, we report the synthesis and characterisation of a series of Pd(II) complexes: Pd(TEEDA)Cl₂, C-1; [Pd(TEEDA)(OH₂)₂](NO₃)₂, C-2; [Pd(TEEDA)(l-cys)](NO₃)₂, C-3; [Pd(TEEDA)(NALC)], C-4; [Pd(TEEDA)(Meth)](NO₃)₂, C-5; and [Pd(TEEDA)(GSH)], C-6 (where TEEDA = N,N,N'-Triethylenediamine, l-cys = l-cysteine, NALC = N-acetyl-l-cysteine, Meth = dl-methionine and GSH = glutathione). UV-Vis spectroscopic characterisation was supported by TD-DFT theoretical simulation using Gaussian09 software. Different reactivity parameters were calculated from the energy difference between HOMO and LUMO of the complexes by DFT. The bonding mode of the labile ligands was confirmed by NBO analysis. Interaction of the complexes with DNA has been observed by gel electrophoresis experiment. DNA binding nature as well as binding constants of the complexes were measured with UV-Vis and fluorescence spectroscopic method. The binding nature of the complexes with DNA was confirmed by viscometric titration. Interaction of the complexes with BSA was investigated by UV-Vis and fluorescence titration method. Cytotoxic activity of the Pd(II) complexes was evaluated on A549 (lung carcinoma epithelial cells), HCT116(Colorectal Carcinoma) and HEK293 (Human embryonic kidney cells) cell lines. The ROS generation in the presence of the complexes was tested both on cancer cell lines A549 and HCT116 as well as human normal cell HEK293.

Design, Structural Inspection and Bio-Medicinal Applications of Some Novel Imine Metal Complexes Based on Acetylferrocene

Some novel imine metal chelates with Cr³⁺, Mn²⁺, Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Cd²⁺ cations were produced from 2-acetylferrocene and 3-aminophenol. The new acetylferrocene azomethine ligand ((Z)-cyclopenta-1,3-dien-1-yl(2-(1-((3-hydroxyphenyl)imino)ethyl)cyclopenta-2,4-dien-1-yl)iron) and its metal ion chelates were constructed and elucidated using FT-IR, UV/Vis, ¹HNMR, DTA/TGA, CHNClM studies, mass spectrometry and SEM analysis. According to the TGA/DTG investigation, the ferrocene moiety spontaneously disintegrates to liberate FeO. The morphology of the free acetylferrocene azomethine via SEM analysis was net-shaped with a size of 64.73 nm, which differed in Cd(II) complex to be a spongy shape with a size of 42.43 nm. The quantum chemical features of the azomethine ligand (HL) were computed, and its electronic and molecular structure was refined theoretically. The investigated acetylferrocene imine ligand behaves as bidinetate ligand towards the cations under study to form octahedral geometries in case of all complexes except in case of Zn²⁺ is tetrahedral. Various microorganisms were used to investigate the anti-pathogenic effects of the free acetylferrocene azomethine ligand and its metal chelates. Moreover, the prepared ligand and its metal complexes were tested for anticancer activity utilizing four different concentrations against the human breast cancer cell line (MCF7) and the normal melanocyte cell line (HBF4). Furthermore, the binding of 3-aminophenol, 2-acetylferrocene, HL, Mn²⁺, Cu²⁺, and Cd²⁺ metal chelates to the receptor of breast cancer mutant oxidoreductase was discovered using molecular docking (PDB ID: 3HB5).

Synthesis, Spectroscopic, Structural and Molecular Docking Studies of Some New Nano-Sized Ferrocene-Based Imine Chelates as Antimicrobial and Anticancer Agents

The newly synthesized organometallic acetyl ferrocene imine ligand (HL) was obtained by the direct combination of 2-acetyl ferrocene with 2-aminothiophenol. The electronic and molecular structure of acetyl ferrocene imine ligand (HL) was refined theoretically and the chemical quantum factors were computed. Complexes of the acetyl ferrocene imine ligand with metal(II)/(III) ions (Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)) were fabricated. They were inspected by thermal (DTG/TG), spectroscopic techniques (FT-IR, 1H NMR, mass, UV-Vis), molar conductivity, and CHNClM to explicate their structures. Studies using scanning electron microscope (SEM) were conducted on the free acetyl ferrocene imine ligand and its Cd(II) chelate to confirm their nano-structure. To collect an idea about the effect of metal ions on anti-pathogenic properties upon chelation, the newly synthesized acetyl ferrocene imine ligand and some of its metal chelates were tested against a variety of microorganisms, including Bacillus subtilis, Staphylococcus aureus, Salmonella typhimurium, Escherichia coli, Aspergillus fumigatus, and Candida albicans. The ligand and its metal chelate were tested for cytotoxic activity in human cancer (MCF-7 cell viability) and human melanocyte cell line HBF4. It was discovered that the Cd(II) chelate had the lowest IC50 of the three and thus had the prior activity. Molecular docking was utilized to investigate the interaction of acetyl ferrocene imine ligand (HL) with the receptors of the vascular endothelial growth factor receptor VEGFR (PDB ID: 1Y6a), human Topo IIA-bound G-segment DNA crystal structure (PDB ID: 2RGR), and Escherichia coli crystal structure (PDB ID: 3T88).

Spectrophotometric and fluorometric detection of DNA/BSA interaction, antimicrobial, anticancer, antioxidant and catalytic activities of biologically active methoxy substituted pyrimidine-ligand capped copper nanoparticles

New Schiff base ligand (DPMN) was synthesized from the condensation of 2-hydroxy-5-nitrobenzaldehyde and 2-amino-4,6-dimethoxypyrimidine which was confirmed by spectroscopic and analytical methods. Solid air stable copper nanoparticles (DPMN-CuNPs) were synthesized from its copper chloride salt and it is stabilized by the prepared Schiff base ligand by phase transfer assisted synthesis which is a modified Brust-Schiffrin technique. The formation of ligand stabilized copper nanoparticles was confirmed by UV-Visible and FT-IR spectroscopic techniques. The size, surface morphology and quality of DPMN-CuNPs were analyzed by SEM and TEM techniques. Antioxidant activities of DPMN and DPMN-CuNPs with DPPH, SOD, peroxide and nitrous oxide were analyzed by electronic absorption spectroscopy. DNA interaction between DPMN and DPMN-CuNPs with CT-DNA was carried out using electronic absorption, fluorescence, viscometric measurements and cyclic voltammetric techniques. Interaction between BSA and the synthesized compounds analyzed by electronic absorption spectroscopy, Antimicrobial studies confirmed that the synthesized DPMN-CuNPs possess significant biological activities than DPMN. Anticancer results suggest that prepared DPMN-CuNPs have significant anticancer activity against different cancer cell lines and least toxic effect against the normal (NHDF) cell line. Other than the positive response in biological evaluation, our DPMN-CuNPs possess good catalytic activity in methyl orange reduction, methylene blue degradation and nitro phenol reduction.

Transition metal complexes of triazole-based bioactive ligands: synthesis, spectral characterization, antimicrobial, anticancer and molecular docking studies

In the present research work, four new heterocyclic Schiff base ligands (1–4) were synthesized by the condensation of 4-(4-amino-5-mercapto-4H-1,2,4-triazol-3-yl)phenol with salicylaldehyde derivatives in 1:1 molar ratio. The synthesized Schiff base ligands were allowed for complexation with Co(II), Ni(II), Cu(II), Zn(II) metal ions. The structure of the newly synthesized compounds (1–20) was elucidated with the help of various spectral and physicochemical techniques. Spectroscopic data confirm the tridentate nature of ligands which coordinate to the metal via deprotonated oxygen, azomethine nitrogen and thiol sulphur. Conductivity data showed the non-electrolytic nature of complexes. Furthermore, the synthesized compounds were evaluated for their in-vitro antimicrobial activity against four pathogenic bacterial strains and two pathogenic fungal strains. The observed results of microbial activity reveals that compound 3 and its complexes (13–16) were found most potent against the pathogenic strains. In addition, the anticancer activity of all the synthesized compounds was evaluated against human carcinoma cell lines i.e. HCT-116, DU145 and A549 using MTT assay. Among the tested compounds 12, 19, and 20 were found to show promising potency against the cancer cell lines. To rationalize the preferred modes of interaction of most potent compounds with the active site of human EGFR protein (PDB id: 5XGM), molecular docking studies were performed.

Computational and experimental insight into antituberculosis agent, (E)-benzyl-2-(4-hydroxy-2-methoxybenzylidene) hydrazinecarbodithioate: ADME analysis

A new Schiff base, (E)-benzyl-2-(4-hydroxy-2-methoxybenzylidene)hydrazinecarbodithioate (compound 1) has been synthesized and experimentally characterized by the IR, UV-Vis, ¹H-NMR and mass spectroscopies. The theoretical study of the synthesized compound was evaluated using the density functional theory (DFT) at B3LYP/6-31G+(d,p) basis set. The electronic absorption spectrum of compound 1 was evaluated using time-dependent density functional theory. Besides, in silico studies were done for the prediction of absorption, distribution, metabolism and excretion profiles of compound 1. According to the result, the theoretical data were well fitted with the experimental values. The studied compound has low chemical reactivity and high kinetic stability. In the molecular electrostatic potential map, the negative and positive potential sites were found around electronegative atoms and hydrogen atoms of compound 1, respectively. The 97.75% Lewis and 2.25% non-Lewis structure were present in the studied molecule. The molecular docking results reveal that compound 1 can be used as antituberculosis agent as compare to ethambutol.

Temperature and salt effects of the kinetic reactions of substituted 2-pyridylmethylene-8-quinolyl iron (II) complexes as antimicrobial, anti-cancer, and antioxidant agents with cyanide ions

Kinetics of substitution reaction of three high-spin pyridylmethylene-8-quinolyl iron (II) complexes by CN– ions were studied spectrophotometrically in various ratios of aqueous–methanol binary mixtures at 298 ± 0.2 K. Kinetics of the substitution reaction follow the rate law (k2[CN−][complex]) on applying of the conditions of the pseudo first order reaction. Reactivity of the reaction was investigated in terms of ligand moiety and solvent effects. The rate of the reaction increased as the co-solvent methanol ratio increased. This reactivity trend is predominantly due to increases in the activity coefficient of those hydrophobic complexes in the organic methanol co-solvent, depending upon the hydrophobicity of the substituent groups (R) in the coordinated ligand in the complexes. Reactivity trends of the prepared complexes in the presence of the inserted hydrophobic salts such as tetrabutylammonium bromide (TBAB), tetraethylammonium bromide (TEAB), and tetramethylammonium bromide (TMAB) or hydrophilic salt potassium bromide (KBr) were studied. The observed decrease in the rate constants with increasing salt concentration was due to the cationic character of the reacting complexes. In addition, the synthesized compounds were tested for antimicrobial activity against selected strains of microbes. The results showed that the order of reactivity of the investigated complexes against the selected microbes were as follows: ppaqFe > paaqFe > pmaqFe. In addition, the investigated ligands and their Fe(II) complexes were screened for anticancer activities against several cell lines of cancer. The ppaqFe complex showed the best cytotoxic efficiency against the selected cancer lines (IC50 = 8.75–21.50 µg/µl), whereas the pmaq ligand showed the lowest cytotoxic efficiency (IC50 = 58.25– 72.40). Furthermore, the antioxidant potential of the presented compounds was studied by applying DPPH assays and showed a potential activity compared with standard vitamin C. The excellent antimicrobial and anticancer activities of the investigated Fe(II) chelates compared with literature values are promising and deserve further study.

Development of New Thiazole Complexes as Powerful Catalysts for Synthesis of Pyrazole-4-Carbonitrile Derivatives under Ultrasonic Irradiation Condition Supported by DFT Studies

In this study, we are interested in preparing Fe(III), Pd(II), and Cu(II) complexes from new thiazole derivatives. All syntheses were elaborately elucidated to estimate their molecular and structural formulae, which agreed with those of mononuclear complexes. The square-planer geometry of Pd(II) complex (MATYPd) was the starting point for its use as a heterocatalyst in preparing pyrazole-4-carbonitrile derivatives 4a-o using ultrasonic irradiation through a facile one-pot reaction. The simple operation, short-time reaction (20 min), and high efficiency (97%) were the special advantages of this protocol. Furthermore, this green synthesis strategy was advanced by examination of the reusability of the catalyst in four consecutive cycles without significant loss of catalytic activity. The new synthesis strategy presented remarkable advantages in terms of safety, simplicity, stability, mild conditions, short reaction time, excellent yields, and use of a H₂O solvent. This catalytic protocol was confirmed by the density functional theory (DFT) study, which reflected the specific characteristics of such a complex. Logical mechanisms have been suggested for the successfully exerted essential physical parameters that confirmed the superiority of the Pd(II) complex in the catalytic role. Optical band gap, electrophilicity, and electronegativity features, which are essential parameters for the catalytic behavior of the Pd(II) complex, are based mainly on the unsaturated valence shell of Pd(II).

Second-order NLO properties and two-state switching effects of transition metal redox complexes of iron and cobalt: A DFT study

Designing switchable materials with large contrasts of nonlinear optical properties has been the focus of research in recent decades because of their widespread applications. Redox-active metal complexes due to charge transfer excitation are suitable to produce switchable nonlinear optical (NLO) material. In this regard, we present here the redox switchable NLO response of active metal complexes of iron and cobalt. The geometric, electronic, molecular absorption, nonlinear optical properties, and switch "ON/OFF" style of these metal complexes are studied at the CAM-B3LYP/6-31 + G(d) level of theory. NLO responses of these redox metal complexes are described in terms of change in the charge transfer (CT) patterns by time dependent density functional theory (TD-DFT). The highest β_o value of 301534 × 10^-30 esu is noticed in [Fe-ethynyl-ZnP]¹⁺ complex, because of obvious charge transfer transition from metal to ligand i.e meatal-ligand charge transfer (MLCT) in redox metal complex. In each redox metal isomeric pair, the greater hyperpolarizability value of individual isomer is quite consistent with its smaller energy gap (H-Lgap) between highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO), low crucial excitation energy, and bathochromic shift of λ_max. The remarkable β_o contrasts of these isomeric redox complexes illustrate that they can be appropriate for effective redox-triggered NLO switches. Thus, the results reveal that these redox pair complexes show two-state switching "ON/OFF" effect.

Microwave assisted synthesis, experimental and theoretical characterization and antibacterial activity screening of novel azomethine compounds containing thiophene and aminophenol functionality

Eight new azomethine compounds (3a-3h) containing thiophene and aminophenol functionality were synthesized in excellent yields by using conventional heating and microwave assisted synthesis methods. The structures of newly synthesized compounds were characterized by spectroscopic techniques such as UV-Vis, FTIR, ¹H and ¹³C NMR and elemental analysis. UV-Vis and ¹H NMR results show that all compounds prefer the phenol-imine tautomer form in solvent media. The chemical structure of 3a, 3b and 3g was also confirmed by single crystal X-ray diffraction method. The molecular conformations of 3a, 3b and 3g are stabilized by an N⁺-H⋯O^- type intramolecular hydrogen bond in zwitterionic form in the crystalline solid state. The optimized molecular structures, ¹H and ¹³C NMR chemical shift values, UV-Vis spectroscopic parameters, HOMO-LUMO energies, Mulliken (MPA) and natural (NBO) atomic charges, Natural bond orbitals (NBO), molecular electrostatic potential (MEP) maps and solvent accessible surfaces (SASs) for 3a-3h were calculated by using DFT/B3LYP/6-311G(2d,p) approach. The theoretical spectroscopic features obtained by DFT calculations show a very good agreement with the experimental data. In addition, the synthesized compounds (3a-3h) were screened for their antibacterial activities against Bacillus cereus (NRRL-B3711), Bacillus subtilis (NRRL-B4378), Escherichia coli (NRRL B-3008), Staphylococcus aureus (ATCC-6538) and Salmonella typhimurium (ATCC-13311). The results show that investigated compounds have either moderately active, slightly active or inactive among the tested microorganisms. 3a exhibited the stronger antibacterial activity against all test bacteria than other compounds. It also has been observed that compounds with relatively low HOMO-LUMO energy gaps exhibit better antibacterial effects.

Non-Linear Optical Property and Biological Assays of Therapeutic Potentials Under In Vitro Conditions of Pd(II), Ag(I) and Cu(II) Complexes of 5-Diethyl amino-2-({2-[(2-hydroxy-Benzylidene)-amino]-phenylimino}-methyl)-phenol

Herein, we report facile procedures for synthesis of a new Schiff base ligand (H₂L,5-Diethylamino-2-({2-[(2-hydroxy-benzylidene)-amino]-phenylimino}-methyl)-phenol) and its Ag(I), Pd(II) and Cu(II) complexes. The structure of the H₂L ligand as well as its metal complexes was deduced based on wide range of analytical, structural and spectroscopic tools, along with theoretical evidence via density functional theory (DFT) calculations. The obtained results indicated that the Schiff base (H₂L) ligand acts as a tetradentate N₂O₂ donor with two azomethine nitrogen’s (N1, N2) and two deprotonated phenolic oxygens (O1, O2) atoms. A distorted octahedral structure is assigned to [CuL(OH₂)₂]·3/2H₂O complex and square planar structure for PdL and AgL complexes. The electronic structure and non-linear optical (NLO) property of the prepared compounds were discussed theoretically by the B3LYP/GENECP program. Results revealed that all complexes have non-planner geometries as indicated from the dihedral angles. The charge transfer occurs within the synthesized complexes as indicated from the calculated energy gap between HOMO and LUMO energies. The H₂L ligand and its complexes are excellent candidates for NLO materials as implied from their hyperpolarizabilities and polarizabilities values. The biological activities of the prepared complexes against selected microorganisms and cancer cell lines gave good growth inhibitory effect. The biocidal potencies of the ligand and its complexes can be arranged as follows: AgL > CuL > PdL > H₂L, as compared to the used standard drugs. The antiproliferative activity of the studied complexes against different carcinoma cell lines such as liver (Hep-G2), breast (MCF-7) and colon (HCT-116) followed the order H₂L < AgL< PdL < CuL < vinblastine. Probing the binding interactions of prepared complexes with calf thymus (CT)-DNA using electronic absorption, gel electrophoresis and viscosity measurements revealed strong interaction via intercalation modes, as also evidenced by their molecular docking study.