Quantitative study on a simple electrochemical dsDNA-pregabalin biosensor; multi-spectroscopic, molecular docking and modelling studies.

Pregabalin (PGB) is a γ-aminobutyric acid (GABA) alkylated analog prescribed to treat neuropathic pain, fibromyalgia, and postherpetic neuralgia. Using analytical, spectroscopic methods and molecular docking and molecular dynamics (MD) simulations, a detailed experimental and theoretical investigation was conducted into the binding process and interactions between PGB and double-stranded fish sperm deoxyribonucleic acid (dsDNA). It was evident from the collected experimental results that PGB binds with ds-DNA. PGB attaches to dsDNA via minor groove binding, as demonstrated by the results of electrochemical studies, UV-Vis absorption spectroscopy, and replacement study with ethidium bromide and Hoechst-32588. PGB's binding constant (Kb) with dsDNA, as determined by the Benesi-Hildebrand plot, is 2.41×104 ± 0.30 at 298 K. The fluorescence investigation indicates that PGB and dsDNA have a binding stoichiometry (n) of 1.21 ± 0.09. Molecular docking simulations were used in the research to computational determination of the interactions between PGB and dsDNA. The findings demonstrated that minor groove binding was the mechanism by which PGB interacted with dsDNA. Based on the electrochemically responsive PGB-dsDNA biosensor, we developed a technique for low-concentration detection of PGB utilizing differential pulse voltammetry (DPV). The voltammetric analysis of the peak current decrease in the deoxyadenosine oxidation signals resulting from the association between PGB and dsDNA enabled a sensitive estimation of PGB in pH 4.80 acetate buffer. The deoxyguanosine oxidation signals exhibited a linear relationship between 2 and 16 µM PGB. The values for the limit of detection (LOD) and limit of quantitation (LOQ) were 0.57 µM and 1.91 µM, respectively.

Development and Fabrication of a Molecularly Imprinted Polymer-Based Electroanalytical Sensor for the Determination of Acyclovir.

Acyclovir (ACV), a synthetic nucleoside derivative of purine, is one of the most potent antiviral medications recommended in the specific management of varicella-zoster and herpes simplex viruses. The molecularly imprinted polymer (MIP) was utilized to create an effective and specific electrochemical sensor using a straightforward photopolymerization process to determine ACV. The polymeric thin coating was developed using the template molecule ACV, a functional monomer acrylamide, a basic monomer 2-hydroxyethyl methacrylate, a cross-linker ethylene glycol dimethacrylate, and a photoinitiator 2-hydroxy-2-methyl propiophenone on the exterior of the glassy carbon electrode (GCE). Scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry were employed for the purpose of characterizing the constructed sensor (AM-ACV@MIP/GCE). Differential pulse voltammetry and a 5 mM ferrocyanide/ferricyanide ([Fe(CN)6]3-/4-) redox reagent were used to detect the ACV binding to the specific cavities on MIP. The study involves density functional theory (DFT) calculations, which were conducted to investigate template-functional monomer interactions thoroughly, calculate template-functional monomer interaction energies, and determine the optimal template/functional monomer ratio. DFT calculations were performed using Becke's three-parameter hybrid functional with the Lee-Yang-Parr correlation functional (B3LYP) method and 6-31G(d,p) basis set. The sensor exhibits linear performance throughout the concentration region 1 × 10-11 to 1 × 10-10 M, and the limit of detection and limit of quantification were 7.15 × 10-13 M and 2.38 × 10-12 M, respectively. For the electrochemical study of ACV, the sensor demonstrated high accuracy, precision, robustness, and a short detection time. Furthermore, the developed electrochemical sensor exhibited exceptional recovery in tablet dosage form and commercial human blood samples, with recoveries of 99.40 and 100.44%, respectively. The findings showed that the AM-ACV@MIP/GCE sensor would effectively be used to directly assess pharmaceuticals from actual specimens and would particularly detect ACV compared to structurally similar pharmaceutical compounds.

Quantification of mirtazapine in tablets via DNA binding mechanism; development of a new HPLC method.

Atypical antidepressant mirtazapine (MIR) is mostly prescribed for the management of major depressive disorder. The identification of MIR in pharmaceutical dosage forms was made possible by developing a novel, quick, sensitive high-performance liquid chromatography (HPLC) approach that was verified in accordance with ICH recommendations. In the first part of this study, HPLC investigations were optimized with regard to variables including pH, working column, mobile phase, temperature, and flow rate. The limit of detection (LOD) was 0.013 ppm, the limit of quantification (LOQ) was 0.044 ppm, and the linear range was computed as 0.5-15 ppm (R2 = 0.9998). The recovery investigation assessed the method's accuracy, which was shown to range between 98.82 and 100.97 %. In the second part, by using UV-vis spectroscopy, HPLC, thermal denaturation, and viscosity measurements, the mechanism of binding interaction of MIR with double-stranded fish sperm deoxyribonucleic acid (dsDNA) has been thoroughly studied. The DNA binding constants (Kb) were determined using UV-Vis absorption and HPLC methods. To investigate the interactions of MIR with dsDNA, molecular docking calculations and additionally, molecular dynamics simulations were performed. Results showed that MIR is located in the minor groove of dsDNA, and in addition to hydrogen bonding, electrostatic interaction is also formed between the aromatic ring of MIR and phosphate oxygen of dsDNA. Finally, a binding characterization study using MIR tablets was also conducted in order to assess the interaction mechanism of the DNA with the drug using the validated analytical procedure developed for the MIR molecule.

The Effect of Polymerization Techniques on the Creation of Molecularly Imprinted Polymer Sensors and Their Application on Pharmaceutical Compounds.

Molecularly imprinted polymers (MIPs) have become more prevalent in fabricating sensor applications, particularly in medicine, pharmaceuticals, food quality monitoring, and the environment. The ease of their preparation, adaptability of templates, superior affinity and specificity, improved stability, and the possibility for downsizing are only a few benefits of these sensors. Moreover, from a medical perspective, monitoring therapeutic medications and determining pharmaceutical compounds in their pharmaceutical forms and biological systems is very important. Additionally, because medications are hazardous to the environment, effective, quick, and affordable determination in the surrounding environment is of major importance. Concerning a variety of performance criteria, including sensitivity, specificity, low detection limits, and affordability, MIP sensors outperform other published technologies for analyzing pharmaceutical drugs. MIP sensors have, therefore, been widely used as one of the most crucial techniques for analyzing pharmaceuticals. The first part of this review provides a detailed explanation of the many polymerization techniques that were employed to create high-performing MIP sensors. In the subsequent section of the review, the utilization of MIP-based sensors for quantifying the drugs in their pharmaceutical preparation, biological specimens, and environmental samples are covered in depth. Finally, a critical evaluation of the potential future research paths for MIP-based sensors clarifies the use of MIP in pharmaceutical fields.

Controlled synthesis and computational analysis of gold nanostars for the treatment of Fusarium oxysporum.

Fusarium oxysporum (F. oxysporum) is linked to the widespread fusarium wilt in plants affecting the quality and yield of food crops. Management of fusarium wilt by synthetic fertilizers poses safety concerns. Safer-by-design nanomaterials synthesized with a greener approach can meet the needs of commercial antifungal drug resistance. Herein, a simple aqueous reduction method has been adopted for the synthesis of anisotropic gold nanostars (AuNSs) using quercetin-para aminobenzoic acid (QPABA) as both a reducing and stabilizing agent at room temperature for the treatment of F. oxysporum. QPABA was used to control the growth of Au3+ star-shaped nanoparticles at increasing concentrations in the ratio of 2 : 1 (QPABA : Au3+ ions) respectively. Transmission electron microscopy (TEM) analysis of the as-prepared gold nanoparticles confirmed the formation of nanostars with sizes of 40 ± 2 nm. The formation of anisotropic gold nanoparticles was evaluated by UV-vis characterizations which showed longitudinal surface plasmon modes at 540 and 800 nm. The gold nanoparticles exhibit excellent antifungal activity against F. oxysporum with the minimum inhibitory concentration (MIC) of 100 µg mL-1 using an agar well-diffusion assay. AuNSs proved to be efficacious in controlling F. oxysporum, as shown in the SEM analysis with a disintegrated cell membrane upon treatment. Computational analysis was performed to determine the specific binding sites on the QPABA ligand for gold ion interactions using the DFT B3LYP method, with a 6-31+G(d) basis set. Results showed that the interaction between Au3+ and QPABA at the 4 and 3 positions yielded the highest stability and formation of gold nanostars. The results suggest that the synthesized AuNSs act as a promising antifungal agent with great potential in treating frequent fungal infections that affect agricultural production.

Elucidation of DNA-Eltrombopag Binding: Electrochemical, Spectroscopic and Molecular Docking Techniques.

Eltrombopag is a powerful adjuvant anticancer drug used in treating MS (myelodysplastic syndrome) and AML (acute myeloid leukemia) diseases. In this study, the interaction mechanism between eltrombopag and DNA was studied by voltammetry, spectroscopic techniques, and viscosity measurements. We developed a DNA-based biosensor and nano-biosensor using reduced graphene oxide-modified glassy carbon electrode to detect DNA-eltrombopag binding. The reduction of desoxyguanosine (dGuo) and desoxyadenosine (dAdo) oxidation signals in the presence of the drug demonstrated that a strong interaction could be established between the eltrombopag and dsDNA. The eltrombopag-DNA interaction was further investigated by UV absorption and fluorescence emission spectroscopy to gain more quantitative insight on binding. Viscosity measurements were utilized to characterize the binding mode of the drug. To shed light on the noncovalent interactions and binding mechanism of eltrombopag molecular docking and molecular dynamics (MD), simulations were performed. Through simultaneously carried out experimental and in silico studies, it was established that the eltrombopag binds onto the DNA via intercalation.

Sample Stacking-Capillary Electrophoretic Analysis of Nitrate and Nitrite in Organic- and Conventional-Originated Baby Food Formulas from Turkey.

Commercially available baby food formulas represent a convenient alternative to homemade meals especially in the recent years. The main purpose of this study is the determination of nitrate and nitrite levels by a sample stacking-capillary electrophoresis technique in the baby foods. The baby foods analyzed were organic-originated, vegetable-based, fruit-based, mixed puree, and a vegetable soup. Vegetables and fruits have high nitrate and nitrite concentrations. Nitrate itself is not actually hazardous. However, nitrite has negative health effects. Thus, baby foods have to be strictly controlled due to the potential health risk of nitrite. In this study, the sample stacking method enhanced the sensitivities of both anions. Nitrate contents ranged from 16.1 to 285 mg/kg with a mean concentration of 149 mg/kg for all samples. The lowest nitrate amount belonged to red fruity milky baby food whereas the highest nitrate was found in organic pumpkin, banana, and carrot mixed puree. The nitrite levels in all the samples were below the LOQ value of the analyzed method. As a conclusion, there is no health risk of the analyzed baby foods regarding nitrate and nitrite levels considering the regulations.

Identification of a 3-(5-methyl-2-thiazolylamino)phthalide as a new minor groove agent.

A new 3-(5-methyl-2-thiazolylamino)phthalide molecule, 3-((5-methylthiazol-2-yl)amino)isobenzofuran-1(3H)-one, was synthesized and characterized experimentally by FT-IR, NMR, UV-Vis, and single-crystal X-ray analysis and theoretically by quantum chemical calculations. The single-crystal X-ray studies revealed that the compound crystallizes in the monoclinic space group P-21/c with unit-cell parameters a = 8.0550(6) Å, b = 6.1386(3) Å, c = 23.3228(18) Å, ß = 97.724(6)° and Z = 4. Optimized geometries and the vibrational frequencies were studied at the density functional theory (DFT) level by using the hybrid functional B3LYP with a 6-311 G (d,p) basis set. The title compound was evaluated for its anti-quorum sensing (anti-QS) activity on Chromobacterium violaceum 12472 and additionally for its antibacterial activity against Staphylococcus aureus 29213, Staphylococcus epidermidis 12228, Pseudomonas aeruginosa 27853, Escherichia coli 25922, and Proteus mirabilis 14153. The lowest MIC value was 0.24 µg/mL for S. aureus 29213 and the highest MIC value was 30.75 µg/mL for E. coli 25922. While anti-bacterial activity was observed in those other than the S. epidermidis and P. Mirabilis, anti-QS activity wasn't detected. Investigations on dsDNA binding affinity indicate that the title compound binds to dsDNA via the groove binding mode. Molecular docking calculations and molecular dynamics simulations results showed also that the title compound prefers binding to the minor groove of dsDNA and remains stable in the minor groove throughout the molecular dynamics simulation.Communicated by Ramaswamy H. Sarma.

Detection of Axitinib Using Multiwalled Carbon Nanotube-Fe2O3/Chitosan Nanocomposite-Based Electrochemical Sensor and Modeling with Density Functional Theory.

In this study, axitinib (AXI), a potent and selective inhibitor of vascular endothelial growth factor receptor (VEGFR) tyrosine kinase and used as a second-generation targeted drug, was investigated electrochemically under optimized conditions using multiwalled carbon nanotubes/iron(III) oxide nanoparticle-chitosan nanocomposite (MWCNT/Fe2O3@chitosan NC) modified on the glassy carbon electrode (GCE) surface. Characterization of the modified electrode was performed using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The adsorptive stripping differential pulse voltammetric (AdSDPV) technique was used for the sensitive, rapid, and precise detection of AXI. The current peak obtained with the MWCNT/Fe2O3@chitosan NC modified electrode was 23 times higher compared to the bare electrode. The developed modified electrode showed excellent electrocatalytic activity in AXI oxidation. Under optimized conditions, the effect of supporting electrolyte and pH was investigated, and 0.1 M H2SO4 was chosen as the electrolyte with the highest peak current for the target analyte. In the concentration range of MWCNT/Fe2O3@chitosan NC/GCE, 6 × 10-9 and 1 × 10-6 M, the limit of detection (LOD) and limit of quantification (LOQ) values were calculated to be 0.904 and 0.0301 pM, respectively. Tablet and serum samples were used for the applicability of the developed sensor, relative standard deviation (RSD) values for all samples were below 2%, and the recovery results were 99.23 and 101.84%, respectively. The MWCNT/Fe2O3@chitosan NC/GCE designed to determine AXI demonstrated the applicability, selectivity, precision, and accuracy of the sensor. The mechanism of electron transfer from the modified GCE surface to the analyte solution is studied via modeling the modified GCE surface by the density functional theory (DFT) method at B3LYP/6-311+g(d,p) and M062X/6-31g(d,p) levels. We observed that the iron oxide nanoparticles play an important role in channeling electron flow from the analyte solution to the MWCNT-coated GCE electrode surface. Adsorption of the nanocomposite material onto the GCE surface occurs via strong electrostatic interactions, including ionic and hydrogen bond formations. During the adsorption-controlled oxidation process of the axitinib, the electrons are transferred via the highest occupied molecular orbital (HOMO) localized on the iron oxide moiety to the lowest unoccupied molecular orbital (LUMO) of the MWCNT/GCE surface.

Deciphering the mechanism and binding interactions of Pemetrexed with dsDNA with DNA-targeted chemotherapeutics via spectroscopic, analytical, and simulation studies.

Pemetrexed is a well-known and widely used antineoplastic drug under the category of cytotoxic, folate anti-metabolites that is used in chemotherapeutic treatments, especially in malignant mesothelioma and non-small cell lung carcinoma. Here, the binding mechanism and interactions of Pemetrexed with double strain fish sperm deoxyribonucleic acid (dsDNA) were studied thoroughly both experimentally and theoretically, using multi-spectroscopic techniques and molecular docking simulations. Our ultimate goal is to understand better the potential of such antineoplastic drugs and, hence, to design drugs with high dsDNA binding affinities and fewer adverse effects. We employed several techniques yielding different but complementary results such as UV, fluorescence, thermal denaturation, electrochemical and viscosity, and molecular docking studies under physiological conditions. Our results revealed that the Pemetrexed binds fairly strongly to dsDNA's minor groove through hydrogen bond interactions with the mostly adenine and guanine bases via its p-carbamide and p-carboxylic groups. MD simulations of the drug-dsDNA complex were followed for 50 ns to confirm that interaction is stable and robust electrostatic interactions were due to hydrogen bonding mostly with the adenine and guanine nucleotides in the minor groove.

Mechanism of Interactions of dsDNA Binding with Apigenin and Its Sulfamate Derivatives Using Multispectroscopic, Voltammetric, and Molecular Docking Studies.

DNA binding investigations are critical for designing better pharmaceutical compounds since the binding of a compound to dsDNA in the minor groove is critical in drug discovery. Although only one in vitro study on the DNA binding mode of apigenin (APG) has been conducted, there have been no electrochemical and theoretical studies reported. We hereby report the mechanism of binding interaction of APG and a new class of sulfonamide-modified flavonoids, apigenin disulfonamide (ADSAM) and apigenin trisulfonamide (ATSAM), with deoxyribonucleic acid (DNA). This study was conducted using multispectroscopic instrumentation techniques, which include UV-vis absorption, thermal denaturation, fluorescence, and Fourier transform infrared (FTIR) spectroscopy, and electrochemical and viscosity measurement methods. Also, molecular docking studies were conducted at room temperature under physiological conditions (pH 7.4). The molecular docking studies showed that, in all cases, the lowest energy docking poses bind to the minor groove of DNA and the apigenin-DNA complex was stabilized by several hydrogen bonds. Also, π-sulfur interactions played a role in the stabilization of the ADSAM-DNA and ATSAM-DNA complexes. The binding affinities of the lowest energy docking pose (schematic diagram of table of content (TOC)) of APG-DNA, ADSAM-DNA, and ATSAM-DNA complexes were found to be -8.2, -8.5, and -8.4 kcal mol-1, respectively. The electrochemical binding constants K b were determined to be (1.05 × 105) ± 0.04, (0.47 × 105) ± 0.02, and (8.13 × 105) ± 0.03 for APG, ADSAM, and ATSAM, respectively (all of the tests were run in triplicate and expressed as the mean and standard deviation (SD)). The K b constants calculated for APG, ADSAM, and ATSAM are in harmony for all techniques. As a result of the incorporation of dimethylsulfamate groups into the APG structure, in the ADSAM-dsDNA and ATSAM-dsDNA complexes, in addition to hydrogen bonds, π-sulfur interactions have also contributed to the stabilization of the ligand-DNA complexes. This work provides new insights that could lead to the development of prospective drugs and vaccines.

Elucidation of binding interactions and mechanism of Fludarabine with dsDNA via multispectroscopic and molecular docking studies.

Fludarabine is a purine derivative, anti-neoplastic drug and is still being used in the treatments of chronic lymphocytic leukemia, small lymphocytic lymphoma, acute myeloid leukemia, Non-Hodgkin's lymphoma. It achieves its function by interacting with DNA. Therefore, the binding interactions of such drugs with deoxyribonucleic acid (DNA) is an important subject for pharmaceutical and biochemical studies aiming at designing better DNA binding drugs. Although DNA binding mode of some of the anti-neoplastic drugs has been studied, DNA interaction of Fludarabine has not been explored yet. For this reason, this work has been dedicated to deciphering the experimental and theoretical investigation of Fludarabine binding mechanism via multispectroscopic techniques including UV absorption spectroscopy, thermal denaturation, fluorescence and FTIR spectroscopy, electrochemical and viscosity measurement methods as well as with molecular docking studies under physiological conditions. We observed in the lowest energy docking poses that Fludarabine binds to DNA via major groove binding mode. The nonplanar and extended structure and hydrogen bonding interactions of Fludarabine with the Adenine-Thymine base-pair played a very decisive role in the binding mode as supported by the experimental results.

SOD activity and DNA binding properties of a new symmetric porphyrin Schiff base ligand and its metal complexes.

4-Methoxy-2,6-bis(hydroxymethyl)phenol (1) was prepared from the reaction of 4-methoxyphenol and formaldehyde. The compound (1) was then oxidized to the 4-methoxy-2,6-diformylphenol (2) compound. Molecular structure of compound (2) was determined by X-ray diffraction method. A new symmetric porphyrin Schiff base ligand 4-methoxy-2,6-bis[5-(4-iminophenyl)-10,15,20-triphenylporphyrin]phenol (L) was prepared from the reaction of the 5-(4-aminophenyl)-10,15,20-triphenylporphyrin (TTP-NH2) and the compound (2) in the toluene solution. The metal complexes (Cu(II), Fe(III), Mn(III), Pt(II) and Zn(II)) of the ligand (L) were synthesized and characterized by the spectroscopic and analytical methods. The DNA (fish sperm FSdsDNA) binding studies of the ligand and its complexes were performed using UV-vis spectroscopy. Additionally, superoxide dismutase activities of the porphyrin Schiff base metal complexes were investigated. Additionally, electrochemical, photoluminescence and thermal properties of the compounds were investigated.

New metal based drugs: spectral, electrochemical, DNA-binding, surface morphology and anticancer activity properties.

The NSAID piroxicam (PRX) drug was used for complex formation reactions with Cu(II), Zn(II) and Pt(II) metal salts have been synthesized. Then, these complexes have been characterized by spectroscopic and analytical techniques. Thermal behavior of the complexes were also investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to fish sperm double strand DNA (FSFSdsDNA) with UV spectroscopy. UV studies of the interaction of the PRX and its complexes with FSdsDNA have shown that these compounds can bind to FSdsDNA. The binding constants of the compounds with FSdsDNA have also been calculated. The morphology of the FSdsDNA, PRX, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with FSdsDNA has been studied by means of differential pulse voltammetry (DPV) at FSdsDNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism. The effect of proliferation PRX and complexes were examined on the HeLA and C6 cells using real-time cell analyzer with four different concentrations.

Synthesis, crystal structures, DNA binding and cytotoxicity of two novel platinum(II) complexes containing 2-(hydroxymethyl)pyridine and pyridine-2-carboxylate ligands.

Two new platinum(II) complexes, trans-[Pt(2-mpy)(2)]·4H(2)O (1) and [PtCl(2-pyc)(2-hmpy)]·H(2)O (2), where 2-hmpy=2-(hydroxymethyl)pyridine, 2-mpy=deprotonated 2-hmpy and 2-pyc=pyridine-2-carboxylate, have been synthesized and characterized by elemental analysis, IR, NMR, and X-ray crystallography. The DNA binding affinities of these complexes for Fish Sperm DNA (FS-DNA) were investigated using fluorescence, viscosity, thermal denaturation and gel electrophoresis measurements. Fluorescence analysis indicates that complex 1 binds to DNA by a single intercalative mechanism, while complex 2 exhibits two types of interactions such as intercalation and covalent binding. Gel electrophoresis assay demonstrates ability of the complexes to cleavage the supercoiled pBR322 plasmid DNA. The in vitro cytotoxicities of both complexes were preliminarily evaluated and the cytotoxicity of complex 1 against the human lung cancer cells (H1299) is similar to oxaliplatin, but higher than transplatin and carboplatin.

Tetradentate Schiff base ligands and their complexes: synthesis, structural characterization, thermal, electrochemical and alkane oxidation.

Three Schiff base ligands (H(2)L(1)-H(2)L(3)) with N(2)O(2) donor sites were synthesized by condensation of 1,5-diaminonapthalene with benzaldehyde derivatives. A series of Cu(II), Co(II), Ni(II), Mn(II) and Cr(III) complexes were prepared and characterized by spectroscopic and analytical methods. Thermal, electrochemical and alkane oxidation reactions of the ligands and their metal complexes were investigated. Extensive application of 1D ((1)H, (13)C NMR) and 2D (COSY, HETCOR, HMBC and TOSCY) NMR techniques were used to characterize the structures of the ligands and establish the (1)H and (13)C resonance assignments of the three ligands. Ligands H(2)L(1) and H(2)L(3) were obtained as single crystals from THF solution and characterized by X-ray diffraction. Both molecules are centrosymmetric and asymmetric unit contains one half of the molecule. Catalytic alkane oxidation reactions with the transition metal complexes investigated using cyclohexane and cyclooctane as substrates. The Cu(II) and Cr(III) complexes showed good catalytic activity in the oxidation of cyclohexane and cyclooctane to desired oxidized products. Electrochemical and thermal properties of the compounds were also investigated.

Synthesis of trimethoprim metal complexes: Spectral, electrochemical, thermal, DNA-binding and surface morphology studies.

Complexes of trimethoprim (TMP), with Cu(II), Zn(II), Pt(II), Ru(III) and Fe(III) have been synthesized. Then, these complexes have been characterized by spectroscopic techniques involving UV-vis, IR, mass and (1)H NMR. CHN elemental analysis, electrochemical and thermal behavior of complexes have also been investigated. The electrochemical properties of all complexes have been investigated by cyclic voltammetry (CV) using glassy carbon electrode. The biological activity of the complexes has been evaluated by examining their ability to bind to calf-thymus DNA (CT DNA) with UV spectroscopy and cyclic voltammetry. UV studies of the interaction of the complexes with DNA have shown that these compounds can bind to CT DNA. The binding constants of the complexes with CT DNA have also been calculated. The cyclic voltammograms of the complexes in the presence of CT DNA have shown that the complexes can bind to CT DNA by both the intercalative and the electrostatic binding mode. The antimicrobial activity of these complexes has been evaluated against three Gram-positive and four Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with the reference drug TMP. Almost all types of complexes show excellent activity against all type of bacteria and fungi. The morphology of the CT DNA, TMP, metal ions and metal complexes has been investigated by scanning electron microscopy (SEM). To get the SEM images, the interaction of compounds with CT DNA has been studied by means of differential pulse voltammetry (DPV) at CT DNA modified pencil graphite electrode (PGE). The decrease in intensity of the guanine oxidation signals has been used as an indicator for the interaction mechanism.

Structural characterization and electrochemical properties of novel salicylidene phosphonate derivatives.

In this study, three novel salicylidene phosphonate ligands, diethyl (4-{[(1E)-(2-hydroxyphenyl)methylidene]amino}benzyl)phosphonate (HL1), diethyl (4-{[(1E)-(2-hydroxy-3-methoxyphenyl)methylidene]amino}benzyl)phosphonate (HL2) and diethyl (4-{[(1E)-(2,4-dihydroxyphenyl)methylidene]amino}benzyl)phosphonate (HL3) were synthesized and characterized by the analytical and spectroscopic techniques. We obtained their single crystals from the ethanolic solution. There are intramolecular phenol-imine hydrogen bonds in all three compounds between O1 and N1 atoms. The ligand HL3 contains a second phenol group and this is makes an intermolecular hydrogen bond with the phosphine oxide of a neighbouring molecule O2-O3 (under symmetry operation -x, 0.5+y, 0.5-z). In order to investigate the redox behaviours of the salicylidene phosphonate ligands (HL1-HL3), we were studied electrochemical properties of the ligands at the different pH and scan rates.

Synthesis, structural characterization, catalytic, thermal and electrochemical investigations of bidentate Schiff base ligand and its metal complexes.

In this study, we prepared the Schiff base ligand (L) and its Cu(II), Co(II) and Ni(II) complexes. The compounds were characterized by the analytical and spectroscopic methods. The ligand (L) behaves as a bidentate ligand and coordinates to the metal ions via the nitrogen atoms. The complexes have the mononuclear structures. The analytical and spectroscopic results indicated that the chloride ions coordinate to the metal ions. The complexes have the general formulae [M(L)(Cl)(2)] (M: Cu(II), Co(II) and Ni(II) metal ions). Electrochemical properties were investigated as ligand and metal centres in the different solvents and at the scan rates, respectively. The thermal properties of the metal complexes were studied in the N(2) atmosphere. We investigated the improved catalytic activity of the Cu(II), Co(II) and Ni(II) complexes on the cyclohexane as a substrate. Obtained data showed that the best catalyst is the Cu(II) complex. The single crystal of the ligand (L) was obtained from CH(3)CN solution. There is a C-H...N H-bond linking the molecules into chains (C6)...N(2) 3.4415(18)A under symmetry operation (x+1,y,z) as well as pi-pi stacking on the outside of the "V" shape--nothing on the inside.

Synthesis, structural characterization, thermal and electrochemical studies of the N,N'-bis[(3,4-dichlorophenyl)methylidene]cyclohexane-1,4-diamine and its Cu(II), Co(II) and Ni(II) metal complexes.

In this study, N,N'-bis[(3,4-dichlorophenyl)methylidene]cyclohexane-1,4-diamine (L) and its Cu(II), Co(II) and Ni(II) complexes were prepared and characterized by the analytical and spectroscopic methods. The analytical data show the composition of the metal complex to be [M(2)L(Cl)(4)(H(2)O)(2)], where L is the Schiff base ligand. The conductance data indicate that all the complexes are non-electrolytes. The compound (L) behaves as a monodentate ligand. But, obtained complexes have binuclear nature. The electrochemical properties of the metal complexes are dependent on reversible, irreversible and quasi-reversible redox waves in the anodic and cathodic regions due to oxidation and reduction of the metal ions. The single crystal of the ligand (L) was obtained from CH(3)CN solution. Space group and crystal system of the ligand are P2(1)/C and monoclinic, respectively.