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New single crystals and the nanoscale particles of 3D-host-guest supramolecular coordination polymers (SCP1 and 2); ∞3[(Cu3(CN)3)2.(DAHP)], [1,7-diaminoheptane=.(DAHP)] had been synthesized by self-assembly and utilizing ultrasonic radiation, respectively. X-ray single crystal diffraction of SCP1 supported the formation of the [Cu3(CN)3]2 units exhibiting tetrahedral geometry of copper(I) atoms which had been assembled in unique way to construct 3D-network. The neutral [Cu3(CN)3]2 building blocks create pretty-complex structure containing the unique [Cu2(μ3-CN)2] motif with wide cavities enable to capsulate the long chain DAHP as guest molecule. The topology and purity of 1 and 2 had been studied by elemental analysis, PXRD, IR-spectra, TEM and thermogravimetric analysis. The topology of 1 had been compared with the prototype SCPs containing different aliphatic diamines which indicated the effect of structural variability and flexibility of aliphatic diamines on the network structure of these SCP. The catalytic and photo-catalytic activity of the nanosized 2 was studied for mineralization of methylene blue (MB) utilizing H2O2 as an oxidant.

In this work, we investigate the lone pair (lp)…π interaction for the halogens (X2=I2, Br2, Cl2, and F2) binding to the rGO surface. Electronic and optical properties of rGO significantly tuned upon adsorption of halogen molecules, although the weak nature of (lp)…π forces. The structure and optical properties of rGO, rGOI2, rGOBr2, rGOCl2 and rGOF2 adducts were investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT) method. Halogen molecules (X2) stable structures were planer on rGO surface and stabilized by the lone pair X2(lp)…π(C) interactions. The surface oxygen atoms contributed to the stability by the O(lp)… π(X2) charge transfer process. Bader analysis reveals significant charge transfer and bond length elongation for X2 on rGO monolayer sheet in the order I2 > Br2 > Cl2 > F2. Surface adsorption of X2 molecules on rGO surface tunes both band gap energy and optical properties. The TDOS and PDOS reveal that X2 adsorption on rGO surface forms an intermediate states in band gap region, which decrease the energy values. These results are beneficial for photocatalysis and light harvesting applications.

Two novel Mn(II) complexes were prepared from new simple ligands. The two complexes were isolated in the form of 1:1 molar ratio via coordination mode of neutral bidentate. This formula was suggested based on CHN, mass spectra and EDX analysis. HL1 ligand coordinated by C=O and C=N groups, while H2L2 ligand coordinated by C=O13 and C-S groups. The tetrahedral geometry was the structural form suggested for the two Mn(II) complexes according to electronic transitions assign for 6A1g→4Eg(4D) and 6A1g→4T1g(4P). Conductometric titrations were carried out to estimate essential constants for the complex in solution sate. Using density-functional theory (DFT) via Gaussian 09 program, we optimized the structural forms of the ligands and their complexes. Valence double-zeta polarized basis set (6-31G*) and efficient core potential basis set (SDD) level were the two sets adjusted for optimizing the ligands and their Mn(II) complexes, respectively. The calculated parameters as well as the electrostatic potential maps (MEP) support the mode of bonding inside the complexes which agreed with the practical data. Also, functional activity relationships were obtained after calculating important physical parameters which suggest the superiority of two Mn(II) complexes in catalytic behavior with superoxide dismutase (SOD) enzyme. Interestingly, the antioxidant activity of the complexes was examined computationally (in-silico) and practically (in-vitro), to evaluate mimic MnSOD enzyme feature. Pharmacophore query was done according to ligand-based, to get a brief view about the ability of complexes to enhance SOD-enzyme function. The two complexes could being able to resident slightly the active core in 3cei and 2pgc proteins, which leads to improve antioxidant function of SOD-enzyme, to be mimic MnSOD-enzyme. This suggestion was further supported by MOE-docking approach which offered all interaction details. Moreover, in-vitro assay results exhibited antioxidant feature of the two complexes which reach up to 87% and surely considered promising. Finally, from in-silico and in-vitro assessments, we could introduce such two Mn(II) complexes as a mimic MnSOD enzyme in its antioxidant function.

Generally olive oil generated two forms of waste by-products: solid olive residue (SOR) and olive wastewater (OWW). In the present study a promising solution is given to treat both SOR and OWW waste by-products. The first process consists of converting the solid olive residue to activated carbon using pyrolysis process at 600 °C, followed by steam activation procedure at three different temperatures. The attained activated carbon was examined by different experimental techniques such as FTIR, SEM, BET and iodine number. The surface area was increased by increasing stream activation temperature (reach 1020 m2 g−1 BET). However, the steam activation at 700 °C was found to be ideal for environmental and economic performance. On the other hand, the activated carbon at 700 °C displayed high removal capacity of both polyphenolic compounds and COD from olive wastewater. In fact, after 2 h of treatment, 95.5% of COD and 84.2% of polyphenolic compounds were completely removed.

Microwave irradiation was used to create Sn-(5%, 10%, and 15%) doped CdO nanostructures. XRD, FTIR, UV–vis spectra, SEM, EDX, and TEM were used to investigate structural, vibrational, surface morphological, and optical properties of CdO and Tin doped CdO nanostructures. The phase and structure of pure and Tin doped nanostructures are verified by the XRD profile. Debye Scherrer's method was used to measure the mean crystallite sizes of CdO and Tin doped CdO nanostructures. It shows that as the concentration of Sn doping increases, the crystallite size decreases. SEM was used to observe the impact of Tin doping on surface morphology. EDX confirms the existence of Sn, Cd, and O elements in all of the samples. The presence of chemical bonding in various nanostructures is confirmed by a Fourier transform infrared spectrum. With more Sn doping, the optical band gap varied from 1.94 to 1.69 eV. The electric measurement was carried out for all the samples using Hall setup and two probe methods. CdO doped with 10% of Sn samples exhibits better electrical property than the other samples.

Surface adsorption of small molecules modulates both optical and electronic structure, which is beneficial for different applications. The molecular adsorption of halogens X2 (X2 = I2, Br2, Cl2, and F2) was investigated using density functional theory and the dispersion (Wb97xd) module. The electronic structure and optical properties of the pristine graphene oxide (GO) and its molecular complexes with halogens (GOI2, GOBr2, GOCl2, and GOF2) are explored. The adsorption of X2 (X2 = I2, Br2, and Cl2) molecules were stabilized by non-covalent lone pair-π bonding, (O)lp… π, interactions and π-π interactions. The F2 molecule were stabilized by lone pair-π bonding, (O)lp… π, as well as halogen bonding (XB). The GOX2 complexes were energetically stable and optically red shifted in polar solvents. The simulated optical absorption spectra at TD-DFT calculations of GOX2 complexes and TDOS uncover the presence of intermediate sates in the energy gap region, which is beneficial for harvest of visible light and photocatalysis.

Adsorption of CO2 on biopolymers such as cellulose (CELL) and chitosan (CS) attracts researchers’ interest, in particular, the aerogel formation with high surface area and unique physical properties. In this work, we studiedthe molecular adsorption of CO2 molecule on the CELL and CS surfaces by performing density functional theory (DFT) calculations, using dimeric and trimeric structures as model compounds. The structure of the individual CELL and CS along with the molecular adsorbed CO2 systems CELLCO2 and CSCO2 were investigated using B3LYP/6-311++G(d,p) level of theory. The interaction energy of CELLCO2 indicated a weak physical adsorption process, where CSCO2 showed higher binding energies. The co-adsorption of CO2 and H2O on CELL and CS surfaces was also investigated. The results showed that H2O stabilized the adsorption of the CO2 on CELL and CS surface through hydrogen bond (HB), where the adsorption energies increased in the presence of the H2O molecule. The stability of CELLCO2 and CSCO2 was supported by an increase in the charge transfer process. This result highlighted the role of the humidity for the stabilization of CO2 on biopolymers surface.

A novel momonuclear metal chelates were derived from Zn(II), Pd(II), VO(II) and Cr(III) ions with azomethine (BSQ) [BSQ = 4-Bromo-2-(quinolin-8-yliminomethyl)-phenol] ligand. The prepared compounds were subjected to different analytical and spectroscopic techniques as, IR, 1H NMR, UV–Vis, molar conductivity, magnetic moment and thermogravimetric analysis (TGA) to elucidate their structures. Accordingly, the most fitted geometry has been suggested for each complex. The ligand acts as a tri-dentate via NNO donors towards the metal ions inside octahedral geometry with Cr3+, square pyramidal with VO2+, tetrahedral with Zn2+ and square planner with Pd2+ ion. Thermo-kinetic parameters for the complexes have been determined and the values suggest the presence of ordered activated complexes. The reactivity of new compounds towards DNA was examined by different methods and the binding kinds seem to electrostatic, intercalation, or replacement. Also, in-vitro antimicrobial and anticancer potency of the compounds were evaluated. In addition, the therapeutic behavior of the complexes appeared promising towards breast cancer cells (MCF-7) in a concentration-dependent manner. Moreover, the redox potential of the newly synthesized compounds was evaluated and the results reflect suitability of Pd(II) complex in controlling the free radicals. Variable theoretical treatments were performed aiming to confirm the structural formulae as well as the biological assay results. A promising antimicrobial and anticancer behavior was recorded with Pd(II) complex (BSQPd) via in-vitro and in-silico ways.

Mesopores silica nanotubes (MSNTs)-based chemical sensors for the rapid detection and of highly selective Fe2+ ions have been prepared. The novel nanosensors were prepared via immobilization of 1,10-phenanthroline-5-amine (PA) and bathophenanthroline (BP) onto the MSNTs. The resultant PA and BP sensors display high sensitivity for detection the Fe2+ ions in tap water, river water, sea water, two units in simple cycle power station, and biological samples. More interestingly, upon meeting ultra-trace amount of Fe2+ ions, a red complex appears at once. Color changes can be seen from the naked eye and tracked with a smartphone or spectrophotometric techniques. The response time that is necessary to achieve a stable signal was less than 15 s. The Univariate (Univar) calibration technique had been utilized for the determination of figures of merits. The detection limit obtained from the digital image analysis was 19 ppb (7.04 × 10−7 M) for Fe2+ ions, while the obtained from the spectrophotometric method was 6.7 ppb (2.48 × 10−7 M). Therefore, the two sensors had been successfully used in the determination of Fe2+ in several real samples with high sensitivity and selectivity. In addition, they can be used as a simple, rapid, and portable method to detect and quantify the pre rust in any cooler system.

Thyroid hormone inhibition by 1,1-dimethylbiguanide (metformin), a potent drug used to treat type-2 diabetes, has been recently reported. However, the mechanism of inhibition has not yet been explored. Orthogonal hydrogen bonds (HBs) and halogen bonds (XBs) extend the properties of the material for different applications, in addition to allowing the molecular recognition of biomolecules. In this study, the solvent effects on orthogonal HBs and XBs in metformin (MET) complexes with halogen molecules (X2 = I2, Br2, and Cl2) were investigated by experimental and theoretical (DFT) studies. The molecular adducts were investigated using spectroscopic techniques, such as UV–Vis, FT-IR, TGA, and SEM imaging. DFT (rwb97xd and MP2) and experimental (FT-IR of solid complexes) results revealed the presence of cis and trans imine groups (C N H). Upon complexation with X2, two conformations were formed: METX2-I and METX2-II, in which the imine groups were trans and cis, respectively. Orthogonal HBs and XBs were directly involved with the stabilization of METX2-II over METX2-I by ~5.0 kcal/mol. The effect of the solvent on the stability of the complexes was investigated experimentally (using acetonitrile, ethanol, methanol, and dichloromethane) and theoretically (using the polarized continuum model (PCM) at MP2/aug-cc-pvdz. The results demonstrate that the formed complexes were stabilized by orthogonal XBs and HBs in polar solvents. The formation constants measured in different solvents correlate with the stability constants of the complexes (R = 0.95).

Two new VO(II) complexes have been synthesized from ligands based on cyanoacetohydrazide (H2L1 & H2L2). Variable analytical and spectral methods have elucidated these complexes as well as their original ligands. IR, 1H NMR, UV-Vis, Mass, EPR, SEM, EDX, XRD and elemental analysis were the practical techniques applied for characterization. Binegative tetradentate mode was suggested within (VO)2-L1 complex, while neutral tetradentate mode was suggested within (VO)2-H2L2 complex. The geometry of complexes was suggested according to VU-Vis spectra as well as EPR spectra to be a square-pyramidal form. In order to optimize their structural forms and extract critical quantum parameters, the DFT analysis was introduced under valence double-zeta polarized base set (6-31G*). The extracted physical parameters suggest that, the (VO)2-L1 complex has excellent characteristics. Hirshfeld's surface properties, on the other hand, indicate its distinctive crystal properties. The (VO)2-L1 complex was therefore selected to catalyze the synthesis of biodiesel via transesterification processes from waste frying oil. In particular, the physical characteristics and combustion efficiency of the synthesized biofuel suggest its high quality due to absence of Cd and Pb metals. The valuable goal attained in this study is to perform a catalytic function for selected VO(II) complex in preparing an economical product as a biofuel through a low cost and safe process.

A new chlorobis(2-aminomethylbenzimidazole)zinc(II) perchlorate complex [Zn(AMB)2Cl](ClO4) 1 has been synthesized and characterized. Spectral and X-ray structural features led to the conclusion that the zinc(II) complex has a square-pyramidal environment around zinc(II) center with coordination chromophore ZnN4Cl. Different amounts of complex 1 were supported on glassy carbon (GC) electrode yielding three GC-supported complex 1 electrodes with different loading densities (0.2, 0.4, and 0.8 mg cm−2). These electrodes were tested as molecular electrocatalysts for the hydrogen evolution reaction (HER) in phosphate buffer aqueous solutions (pH 7), employing linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Results showed that GC-complex 1 catalysts are highly active for the HER, and this catalytic activity enhances with the loading density. The one with the highest loading density (0.8 mg cm−2) exhibited high HER catalytic activity with low onset potential of −140 mV vs. RHE and a high exchange current density of 0.22 mA cm−2. It required an overpotential of 240 mV to achieve a current density of 10 mA cm−2. It also recorded a turnover frequency (TOF) of 1722 mol of hydrogen per mole of catalyst per hour at overpotential 500 mV, which is comparable with the most active molecular electrocatalysts reported in the literature for H2 generation from aqueous neutral solutions. A catalytic cycle is proposed for the generation of hydrogen by complex 1 and the mechanism of the HER is discussed based on the measured Tafel slope (140 mV dec−1).

An equimolar series of binary complexes of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) with guaifenesin (glyceryl guaiacolate) (H 2 L or Gf) have been synthesized. The Gf ligand is deprotonated and coordinated to the metal ion with both oxygen's donor atoms with 1:1 (metal:Gf) ratio and it is determined by micro-analytical technique. The resulting metal chelates of Gf were characterized using the conductivity measurements, FT-IR, Laser Raman, electronic solid reactance, magnetic susceptibility calculation, 1 H NMR, TGA and ESR spectral studies. The conductivity measurements confirm that all the metal complexes were non-electrolytic in DMSO except for chromium and iron(III) complexes have an electrolytic behavior. Based on spectral and analytical data octahedral geometry is assigned to the Cr(III), Mn(II), Fe(III), Co(II) and Ni(II) complexes with four coordinated water molecules, but the copper and zinc(II) complexes have square planner molecular geometry with two coordinated water molecules. The general molecular formula of the solid Gf complexes has been found as [M(Gf)(H 2 O) n ]· x · y H 2 O, where M = Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II), n = 2 or 4, x = Cl − for (Fe and Cr(III) complexes) and y = 3 for (Cr(III) and Ni(II) complexes). The electrochemical reduction of Gf and its complexes were realized on a platinum wire electrode in Britton–Robinson (BR) buffer using the cyclic voltammetric (CV) technique. The effect of functional groups on reduction potential of the Gf was investigated. A general electrochemical reduction mechanism of the compounds is suggested.

Two oxovanadium(IV) complexes, viz., [VO(Me-IDA)(H 2 O) 2 ] ( 1 ) and NaH[VO(EDTA)]·4H 2 O ( 2 ) (Me-IDA = methyliminodiacetic acid and EDTA = ethylenediaminetetraacetic acid) have been synthesized and characterized by FT-IR, UV–Vis, mass spectrometry, elemental analysis, magnetic moment and thermal analysis, as well as electrochemical measurements including cyclic voltammetry. Both compounds are monomeric with distorted octahedral geometries. Compound 2 has been structurally characterized by using X-ray crystallography. It shows an octahedral V(O)N 2 O 3 coordination geometry, which exhibits chemically significant hydrogen bonding interactions besides showing coordination polymer formation. Compounds 1 and 2 show an irreversible redox peak around +0.80 V versus Ag/AgCl corresponding to one-electron oxidation of V(IV) to V(V). The free radical scavenging activity of compounds 1 and 2 were done using 2,2-diphenyl- 1-picrylhydrazyl (DPPH). Both compounds have shown encouraging ROS scavenging activities. The cytotoxicity effects of both compounds toward two different tumor cells (HePG2 and MCF-7) have been also studied by MTT assay. The IC 50 values obtained, after 48 h incubation at 37 °C for HepG2 and MCF-7 cell lines were 74.23 and 42.04 μg/mL for compound 1 and 65.56 and 48.34 μg/mL for compound 2 , respectively. Conclusively, the present investigation provides preliminary results which suggest that such compounds can be promising alternative antitumor agents.

Two new thione-based nickel complexes, viz., [Ni(Tmipr)2Cl2]⋅2H2O 1 and [Ni(Ttxyly)2] ⋅H2O⋅2CH3OH 2 {Tmipr = 1-(2-isopropylphenyl)-1H-imidazole-2(3H)-thione; Ttxylyl− = hydrotris[1-(2,6-dimethylphenyl)-1H-imidazole-2(3H)-thione]borate anion} have been synthesized. Their structures and properties were characterized by several physicochemical methods, namely elemental and thermal analysis, FT-IR and Raman and UV–Vis spectroscopes, as well as electrical molar conductivity measurements. Structural determination of complex 2 showed that the coordination geometry around nickel atom is distorted tetrahedral with four thione sulfur donors from two molecules of the ligand KTtxylyl. Steric interactions between the xylyl rings appear to be responsible for the formation of the mononuclear nickel(II) complex 2. Molecules of complex 2 are connected via S–H···O hydrogen bonds, involving hydrogen atoms of the coordinated thiones and lattice water molecules. The superoxide dismutase biomimetic catalytic activities of both complexes were tested and found to be promising candidates as functional mimic enzyme to serve for complete superoxide radical’s detoxification. The observed IC50 values of these complexes are 8.38 and 7.4 mM for complexes 1 and 2, respectively.

A series of mixed-ligand complexes, viz., [CuLL'X]Y {L = bipyridine; L' = glycine; X = 0, Y = ClO4− (1); X = Cl, Y = 2H2O (2); X = H2O, Y = NO3− (3); X = CH3COO−, Y = H2O (4)} and {[Cu(Gly)(BPy)]2-μ-(SO4)}(5)} have been synthesized and characterized by means of elemental analysis, spectroscopic (FT–IR, UV–Vis and ESR), and thermal analysis, as well as magnetic moment measurements. Spectral and X-ray structural features led to the conclusion that complexes 2–5 have square-pyramidal environments around copper(II) center with coordination chromophores CuN3OCl and CuN3O2, respectively. Whereas complex 1 displays square planar geometry. The quasi-reversible CuII/CuI redox couple slightly improves its reversibility with considerable decrease in current intensity. Additionally, the antioxidant (superoxide dismutase and catalase) biomimetic catalytic activities of the obtained complexes have been tested and found to be promising candidates as dual functional mimic enzyme to serve for complete reactive oxygen species (ROS) detoxification, both with respect to the superoxide radicals and the related peroxides.

The effect of microstructure and chemistry on the kinetics of passive layer growth and passivity breakdown of some Ti-based alloys, namely Ti-6Al-4V, Ti-6Al-7Nb and TC21 alloys, was studied. The rate of pitting corrosion was evaluated using cyclic polarization measurements. Chronoamperometry was applied to assess the passive layer growth kinetics and breakdown. Microstructure influence on the uniform corrosion rate of these alloys was also investigated employing dynamic electrochemical impedance spectroscopy (DEIS). Corrosion studies were performed in 0.9% NaCl solution at 37 &deg, C, and the obtained results were compared with ultrapure Ti (99.99%). The different phases of the microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Chemical composition and chemistry of the corroded surfaces were studied using X-ray photoelectron spectroscopy (XPS) analysis. For all studied alloys, the microstructure consisted of &alpha, matrix, which was strengthened by &beta, phase. The highest and the lowest values of the &beta, phase&rsquo, s volume fraction were recorded for TC21 and Ti-Al-Nb alloys, respectively. The susceptibility of the investigated alloys toward pitting corrosion was enhanced following the sequence: Ti-6Al-7Nb &lt, Ti-6Al-4V &lt, &lt, TC21. Ti-6Al-7Nb alloy recorded the lowest pitting corrosion resistance (Rpit) among studied alloys, approaching that of pure Ti. The obvious changes in the microstructure of these alloys, together with XPS findings, were adopted to interpret the pronounced variation in the corrosion behavior of these materials.

The effect of microstructure and chemistry of passive films on the kinetics of passive layer growth and passivity breakdown of some Ti-based alloys, namely Ti-6Al-4V, Ti-6Al-7Nb and TC21 alloys was studied. The rate of pitting corrosion was evaluated using cyclic polarization measurements. Chronoamperometry was applied to assess the passive layer growth kinetics and breakdown. Microstructure influence on the uniform corrosion rate of these alloys was also investigated employing Tafel extrapolation and dynamic electrochemical impedance spectroscopy. Corrosion studies were performed in 0.9% NaCl solution at 37 oC, and the obtained results were compared with ultrapure Ti (99.99%). The different phases of the microstructure were characterized by X-ray diffraction and scanning electron microscopy. Chemical composition and chemistry of the corroded surfaces were studied using X-ray photoelectron analysis. For all studied alloys, the microstructure consisted of α matrix, which was strengthened by β phase. The highest and the lowest values of the β phase’s volume fraction were recorded for TC21 and Ti-Al-Nb alloys, respectively. The uniform corrosion rate and pitting corrosion resistance (Rpit) of the studied alloys were enhanced following the sequence: Ti-6Al-7Nb < Ti-6Al-4V << TC21. The corrosion resistance of Ti-Al-Nb alloy approached that of pure Ti. The obvious changes in the microstructure of these alloys, together with XPS findings, were adopted to interpret the pronounced variation in their corrosion rates.

Synthesis of new N′- cyclohexylidene-3‑hydroxy-2-naphthohydrazide (H2L) complexes was carried out by ball milling technique in the lack of solvent (green approach) and then characterized by analytical and spectroscopic techniques. The metal salts used for preparations, were varied in their conjugated anions (Cl−, SO4−2 & OAc−) to investigate the changes in properties of obtained complexes, by changing anions, even with the same ligand. The ligand was coordinated mainly as monobasic with the metal acetate salts, while a neutral with metal chloride or sulfate salts. Such coordination modes were appeared through bidentate or tridentate towards central metals within different molar ratios (1: 1 or 1:2, M:L). Conductometric study was performed for Co(II) complex to estimate the complex stoichiometry and either formation or association constants, in solution state. DMOL3 program was used via DFT/B3LYP method to optimize the studied compounds and to obtain essential quantum parameters. Consequently, we confirmed the coordination of O(11), O(13) and N(16) atoms according to their features appeared in molecular modeling study. In-silico assessment was performed to examine the interaction features of new compounds with pathogenic-DNA, before in-vitro screening. Such assessment was carried out firstly by pharmacophore query within MolPort drug-library to discover the analogues drugs in activity towards DNA proteins. MolPort-007–588–377 and MolPort -000–734–772 were the code numbers of two analogues drugs. Secondly MOE-docking process was executed to explain all interaction features and rank the inhibition activity of complexes. Furthermore, antimicrobial, antioxidant and antitumor activity were investigated for all compounds and Ni(II)-Bis(HL) complex showed excellent antioxidant activity. Whereas, Co(II)-Bis(HL) complex showed excellent cytotoxicity towards liver cancer cells. Finally, the whole characteristics of complexes were changed by changing conjugated anions, even with the same ligand.

The present study examines the role of leguminous compost (LC), humic acids (HA), and phosphate-solubilizing bacteria (P-SB) in alleviating the stress effects of high soil CaCO3 content in Phaseolus vulgaris. Two pot trials for two consecutive seasons, fall 2019 and summer 2020 were implemented in an open greenhouse. A mixed three-way ANOVA, two independent factors (season and soil treatments) and one within factors (time) were used with four replicates. Residual maximum likelihood (REML) analysis was used for the mixed model of the studied traits. Inoculation of calcareous soil with P-SB (a 1:1 mixture of two Pseudomonas sp., Ps. mallei and Ps. cepaceae) significantly exceeded LC, HA, or even LC+HA for the positive results obtained. P-SB facilitated nutrient solubility (e.g., N, K, Fe, and Mn), including conversion of insoluble phosphorous into a form available in the tested soil due to increased soil enzymatic activities (e.g., phosphatases and phytases). This mechanism, combined with a decrease in soil calcium carbonate content and an increase in cation exchange capacity (CEC) and organic matter (OM) content, increased the availability of various nutrients to plants, including P, in the soil, which contributed to the increased plant output. Adequate P content in plants led to a marked decrease in plant acid phosphatase activity under high content of CaCO3. The study concluded that the use of P-SB promotes biological activities, nutrient availability, and thus the productivity of calcareous soils, enabling Phaseolus vulgaris plants to withstand stress produced by high CaCO3 content through the development and/or adoption of potentially effective mechanisms. Strong highly significant interactions between the treatments and time were observed using the Wald’s statistics test, which indicates a positive correlation.

Nanocrystalline lanthanum orthoferrite (LaFeO3) powders have been synthesized using the oxalic acid precursor route. The ferrite precursors were obtained by the auto combustion of aqueous mixtures of lanthanum nitrate and ferric chloride in the presence of oxalic acid as a fuel. This precursor was annealed at different temperatures ranging from 400 to 1200 °C for 2 h. The effect of annealing temperature on the formation, crystalline size, morphology and magnetic properties were systematically studied. The powders formed were investigated using X-ray diffraction, Field emission scanning electron microscope and vibrating sample magnetometer. The results showed that the single-phase LaFeO3 powders were obtained from 800 °C. The average crystalline size increased with increasing the annealing temperature up to 1000 °C. The average crystalline size varied from ≈54.7 to ≈168 nm with the annealing temperature. The saturation magnetization of the ferrite powders was continuously decreased with the increase in annealing temperature up to 1200 °C. The sensing properties for LaFeO3 nanoparticles were examined by modification of carbon paste electrode by LaFeO3. The cyclic voltammograms gave a well-defined redox peaks for K3[Fe(CN)6]/K4[Fe(CN)6] with significant higher peak current values. This may be due to the presence of LaFeO3 which increased the catalytic properties for the prepared sensors by increasing the surface area of the sensor in presence of LaFeO3 nanoparticle oxides which facilitate the formation of Fe(II)/Fe(III) redox couple.

A new vanadate compound, which contains interlamellary, the insulin enhancing agent metformin was prepared. Its structure was established to be [Metformin] 2 [V 2 O 6 ]·H 2 O 1 by using elemental analysis, FT-IR and 1 H– 13 C NMR spectroscopic methods. The crystal structure of 1 shows that each of the two vanadium atoms is coordinated to four oxygen atoms, forming a distorted tetrahedral {VO 4 } that are arranged alternately to form one-dimension { V 2 O 6 } n 2 n − chains. The chains are stabilized by an extensive hydrogen bonding involving oxide ligands of the chains and metformin molecules which fill the space between the stacks of chains. Furthermore, powder X-ray diffraction, EDX-SEM and TGA-DTA analysis of compound 1 are also investigated, which demonstrates its high purity and thermal stability. The thermoanalytical data evidence that compound 1 undergo complete decomposition, resulting in V 2 O 5 as a residual product. Investigation of the glucose lowering activity by oral administration of compound 1 in streptozotocin-induced diabetic rats was examined.

Bimetallic nanoparticles of Au and Ni in the form of alloy nanostructures with varying Ni content are synthesized on reduced graphene oxide (rGO) sheets via a simple solution chemistry route and tested as electrocatalysts towards the hydrogen evolution (HE) and oxygen reduction (OR) reactions using polarization and impedance studies. The Au Ni alloy NPs/rGO nanocomposites display excellent electrocatalytic activity which is found to improve with increasing Ni content in the Au Ni/rGO alloy nanocomposites. For HER, the best Au Ni alloy NPs/rGO electrocatalyst, the one with the highest Ni content, exhibits high activity with an onset overpotential approaching zero versus the reversible hydrogen electrode and an overpotential of only 37 mV at 10 mA cm−2. Additionally, a low Tafel slope of 33 mV dec−1 and a high exchange current density of 0.6 mA cm−2 are measured which are very close to those of commercial Pt/C catalyst. Also, in the ORR tests, this electrocatalyst displays comparable activity to Pt/C. The Koutecky–Levich plots referred to a 4-electron mechanism for the reduction of dissolved O2 on the Au Ni alloy NPs/rGO catalyst. The electrocatalyst thus demonstrates excellent activity towards HER and ORR. Additionally, it exhibits outstanding operational durability and activation after 10,000th cycles assuring its practical applicability.

Reduced graphene oxide (rGO) nanosheets decorated with gold nanoparticles (Au NPs/rGO), palladium nanoparticles (Pd NPs/rGO), and gold–palladium bimetallic nanoparticles (Au–Pd NPs)/rGO are synthesized by a simple solution chemistry approach using ascorbic acid as an eco-friendly reducing agent. These materials are characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-angle annular diffraction field-scanning transmission electron microscopy (HAADF-STEM) and thermogravimetric analysis (TGA). The as-prepared nanocomposites are tested as electrocatalysts for efficient hydrogen evolution in deaerated 0.5 M H2SO4 aqueous solution using polarization and impedance measurements. Experimental findings show that the tested catalysts exhibit fast hydrogen evolution kinetics with onset potentials as low as −17, −7.2, and −0.8 mV vs. RHE for Au NPs/rGO, Pd NPs/rGO, and Au–Pd NPs/rGO, respectively. In addition, Tafel slopes of 39.2, 33.7 and 29.0 mV dec−1 and exchange current densities of 0.09, 0.11, and 0.47 mA cm−2 are measured for Au NPs/rGO, Pd NPs/rGO, and Au–Pd NPs/rGO, respectively. The tested materials not only maintain their high performance after 5000 sweep cycles, but their activity is simultaneously enhanced after this aging process. These findings reveal that the tested catalysts, particularly Au–Pd NPs/rGO, are promising candidates among other noble metal catalysts for hydrogen evolution, approaching the commercial Pt/C catalyst (onset potential: 0.0 mV, Tafel slope: 31 mV dec−1, and exchange current density: 0.78 mA cm−2). The high hydrogen evolution reaction (HER) activity of such materials is likely due to the abundance of active catalytic sites, the increased electrochemically accessible surface area and significantly improved electrochemical conductivity.

A dithiolate-containing a carbamate mononuclear cobalt(II) complex namely, [Co(Boc-S)2] (1), was obtained by the reaction of a methanolic solution of cobalt(II) nitrate hexahydrate with two equimolar amounts of the deprotonated form of tert-butyl N-(2-mercaptoethyl)carbamate (Boc-SH). The cobalt(II) complex (1) was characterized in the solid state and in solution by using FT–IR, Raman, UV–visible, and EI–mass spectroscopies, as well as thermal and X-ray diffraction studies. Spectral data showed that the carbamate (Boc-SH) acts as a mono-anionic bidentate ligand coordinating the cobalt(II) ion through two imine nitrogen and two deprotonated thiolate sulfur donor atoms in a distorted tetrahedral geometry. The thermoanalytical data evidence that the complex is stable up to 165 °C and undergoes complete decomposition, resulting in CoO. TEM imaging of the oxide residue shows its nano size clusters, suggesting that the complex (1) may be used as a precursor for nano-oxides. X-ray powder diffraction patterns evidence an isomorphism among the complex. The redox behavior of the cobalt(II) complex was also investigated by cyclic voltammetry. The reaction of the dithiolate cobalt(II) complex (1) with methyl iodide appears to occur intramolecularly with the cobalt-bound dithiolate, forming the cobalt(II)-bound dithioether complex [Co(Boc–SCH3)2]I2 (2), as a dication complex with a clean second-order reaction of 13.24 × 10−2 M−1·s−1.

Ternary copper(II) and nickel(II) chelates of 2,2′-bipyridyl and glycine ligands with the formula of [Cu(BPy)(Gly)Cl] 1, [Cu(BPy)(Gly)(H2O)]NO3 2 and [Ni(BPy)(Gly)(H2O)2]Cl·H2O 3 were synthesized and structurally characterized by using X-ray crystallography. Copper(II) compounds 1 and 2 form slightly distorted square-pyramidal coordination geometries of CuN3ClO and CuN3O2, respectively. Whereas, nickel(II) compound 3 shows an octahedral coordination geometry of NiN3O3. Kinetic measurements have been made with the objective of correlating the influence of geometry. The thiourea substitution reaction of 1 in water is a monophasic process that involves the subsequent displacement of chloride ligand with k2300 = 21.1 ± 0.8 M−1s−1. The activation parameters, ΔH# = 79.2 ± 2.5 kJ mol−1 and ΔS# = 68.4 ± 8.7 J K−1 mol−1, for the chloride substitution reactions indicate that the reaction follows a dissociative mechanism. The interactions of compounds 2 and 3 towards DNA were examined with the help of absorption spectroscopic technique. The binding constants (Kb) of 2 and 3 to DNA were found to be 4.7 × 105 and 2.4 × 105 M−1, respectively, indicating that both compounds show good binding activity to calf thymus DNA. The nuclease mimic activity of both 2 and 3 was also assessed by its ability to cleave super coiled plasmid DNA to nicked and linear forms in the absence of any external additives. On the other hand, the quasi-reversible CuII/CuI redox couple slightly improves its reversibility with a considerable decrease in current intensity. All the experimental results indicated that the bipyridyl mixed copper(II) complex 2 intercalates more effectively into the DNA base pairs.

Two new dithiolate copper(II) and nickel(II) complexes with the ligand tert-butyl N-(2-mercaptoethyl)-carbamate (Boc-SH) were prepared. Their structures were established to be [(Boc-S)2M], where M=Cu (1) and Ni (2) by using elemental analysis, thermal analysis, molar conductivity, FT-IR, Raman, UV/VIS, and ESR as well as EI-mass spectroscopic methods. The X-ray structure of the ligand Boc-SH was also determined. Spectral data showed that the carbamate ligand act as anioinic bidentate through one immine nitrogen and one thiolate sulfur donor atoms. The spectral techniques suggest that both complexes appear to have square planar geometries. The very low electrical conductance of the two complexes supports their neutral nature. The redox behaviors of the obtained complexes were also investigated by cyclic voltammetry. The monomeric nature of both complexes was assessed from their magnetic susceptibility values. The thermoanalytical data evidence that complex (2) is stable up to 165°C and undergo complete decomposition, resulting in NiO as a residual product. The TEM image of the obtained oxide residue showed its nanosize cluster, suggesting that complex (2) may be used as a precursor for the formation of nanooxide. The methylation reactions of the two dithiolate complexes (1) and (2) with methyl iodide appear to occur intramolecularly at the metal(II)-bound dithiolates, forming the metal(II)-bound dithioether complexes [M(Boc-SCH3)2]I2 with clean second-order constants of 7.95×10(-2) and 10.59×10(-2) M(-1) s(-1), respectively.

Four new mixed ligand nickel(II) complexes, viz., [Ni(Barb)2(H2O)4] 1, [Ni(Barb)2(en)2] 2, [Ni(Barb)2(pn)2] 3, and [Ni(Barb)2(BPA)(H2O)] 4 (Barb = 5,5-diethylbarbiturate, en = ethylenediamine, pn = propylenediamine, and BPA = bis(2-picolyl)amine) have been synthesized and characterized by means of elemental analysis, spectroscopic (FT-IR, Raman, and UV–Vis), and thermal analysis measurements. The spectral techniques suggest that all the nickel(II) complexes (1–4) exhibit octahedral geometry. The very low electrical conductance of the complexes supports their neutral nature. The monomeric nature of the complexes was assessed from their electronic spectra. X-ray diffraction studies were performed for the drug Barb-H and its nickel(II) complex 2. Complex 2 crystallizes in monoclinic space group P21/c with Z = 2. The barbital drug is N-coordinated and the en molecules act as bichelating ligands, leading to an NiN6 octahedral coordination. Molecules of complex 2 are connected via N H⋯O hydrogen bonds, involving hydrogen atoms of both Barb and en ligands. The redox behavior of all complexes was investigated by cyclic voltammetry. Superoxide dismutase activity of these complexes has also been measured.

Preparation, spectroscopic characterization, electrochemical studies, and theoretical calculations of albendazole (Albz) and its mononuclear ferric(III) complex, [Fe(Albz)(Cl)3(H2O)], are described. Based on infrared and electronic spectra as well as magnetic measurements Albz molecule seems to be a neutral bidentate ligand via carbonyl group and NH of five-member ring with octahedral fashion toward Fe(III) ions. The thermogravimetric analysis confirms the presence of water molecules existed inside the coordination sphere. The kinetic parameters were estimated and gave an idea about the stability of ferric(III)–Albz complex dependent of TG–DTG curves.

Solution studies of the tetradentate ligand tris(2-benzylaminoethyl)amine, BzTren with both zinc(II) and copper(II) salts were investigated in aqueous methanol (33% v/v) by means of 1H NMR, potentiometric, and UV-visible titrations as well as cyclic voltammetry. Subsequently, their zinc(II) and copper(II) complexes [BzTren-M(OH2)]2+ 1 and 2 (M2+ = Zn2+ and Cu2+) were synthesized and fully characterized by using FT-IR spectroscopy, elemental analysis, and thermal analysis. Complexes 1 and 2 are investigated kinetically for the catalytic hydrolysis of the toxic organophosphate parathion at 50 °C in aqueous methanol (33%, v/v). The kinetic results indicate that copper(II) complex 2 is more active than zinc(II) complex 1, presumably a reflection of the effective electron-withdrawing as well as the greatest electrophilicity of copper(II) ion.

A novel, simple, sensitive and highly selective pseudo-carbon paste electrode modified with poly(acrylic) acid (PCPE-PAA) was described to be useful for the electrochemical determination of ephedrine substance. The PCPE-PAA electrode was characterized using scanning electron microscope (SEM) and cyclic voltammetry. Cyclic voltammogram for ephedrine shows only one anodic oxidation peak at 1.15 V (vs. SCE) using Britton–Robinson buffer (pH 9). Theoretical calculations were performed using PM3 method to be helpful in studying the electrochemical behavior of ephedrine. The highest occupied orbitals (HOMO) of ephedrine and the lowest unoccupied orbitals (LUMOs) of its oxidation product (methcathinone) are mainly localized in the side chain of benzene ring. The values of HOMOs, LUMOs and atomic charges clearly indicate that the oxidation process occurs on the hydroxyl group of ephedrine forming ketone group, supporting the proposed electrochemical mechanism. Square wave voltammetry was used for the direct electrochemical determination of ephedrine. Ephedrine gives a linear range from 6 × 10−5 to 1 × 10−3 M with a correlation coefficient of 0.998 and a relative standard deviation of 2.165 × 10−7. A lower detection limit of 3.5 × 10−7 M was obtained. The effect of some interferences such as ascorbic acid, uric acid, urea, glucose and glycine on the peak height of ephedrine was examined. The suggested method has been applied successfully for the direct electrochemical determination of ephedrine in urine and different pharmaceutical formulations.

The electrochemical behavior of caffeine was investigated by using a simple, cheap, and highly selective pseudo carbon paste electrode. The electrode was characterized using scanning electron microscope (SEM). Cyclic voltammetry of caffeine showed only one oxidation peak at 1.46 V (vs. SCE) in phosphate buffer pH 7. Chemical calculations were performed using PM3 method to prove the electrochemical oxidation mechanism of caffeine studied by cyclic voltammetry. Square wave voltammetry was used for the direct electrochemical determination of caffeine. The effect of different experimental parameters was investigated on the peak height of caffeine. Caffeine showed a linear calibration curve ranged from 1 × 10−6 to 1 × 10−3 M, with 3.03 × 10−7 standard deviation and a correlation coefficient of 0.999. A lower detection limit of 3.48 × 10−7 M was obtained. The effect of ascorbic acid and paracetamol on the peak height of caffeine was studied. The proposed method has been successfully applied for the direct electrochemical determination of caffeine in different real samples such as tea, coffee, cola, and pharmaceutical formulations.

Interaction of the tridentate ligand bis(2-picolyl)amine L with copper(II) salts gave a series of copper(II) complexes with the formula types: [LCu(X)2] (X = Cl− 1, = Br− 2), [(LCu(H2O)(μ-SO4)(LCu(H2O)]SO4 3, [LCu(OAc)](OAc)H2O 4, [LCu(H2O)2](Y)2 (Y = NO 3 - 5, = ClO 4 - 6). Their structures and properties were characterized by elemental analysis, thermal analysis (TGA), IR, UV–vis and ESR spectroscopy, electrochemical measurements including cyclic voltammetry and electrical molar conductivity, and magnetic moment measurements. A square pyramidal geometry is proposed for the halogeno complexes 1 and 2 in monomeric structures. For sulfate complex, the sulfate group bridged two copper(II) ions of the two [N3O] donor units to give the dimeric complex molecule 3 in square pyramidal environment around the copper(II) ions. In the case of complexes 4–6, square planar stereochemistries in monomeric structures are suggested. The SOD biomimetic catalytic activity of the obtained complexes was assessed for their ability to inhibit the reduction of nitroblue tetrazolium (NBT). The catalytic efficiency of O 2 - scavenging by complexes depends on the nature of the particular acidic anion radical incorporated in the complex molecule and follows the order: NO 3 - > ClO 4 - > Br- ⩾ Cl− > SO 4 - > AcO−. A probable mechanistic implications for the catalytic dismutation of O 2 - by copper(II) complexes are proposed. Furthermore, complex 1 exhibits significant hydrolytic cleavage of the genomic DNA in the absence of any external additives. In addition, the in vitro study of cytotoxicity of complex 1 on colon cancer cell line (Caco-2) indicates that the complex has the potential to act as an effective anticancer drug with IC50 value of 156 ± 0.35 μM.

Rates of corrosion of low alloy ASTM A213 grade T22 boiler steel were monitored in aerated stagnant 0.50 M HCl solutions at different temperatures (283–303 K) using Tafel extrapolation method and the non-destructive electrochemical frequency modulation (EFM) technique, complemented with XPS examinations. Serine (Ser) was introduced as a corrosion-safe inhibitor. Corrosion rates (in μm y −1 ) obtained from these two methods was in good agreement. Tafel plots showed that Ser acted mainly as a cathodic-type inhibitor. The inhibition process was attributed to the formation of an adsorbed film on the metal surface that protects the metal against corrosive agents. XPS examinations of the electrode surface confirmed the existence of such adsorbed film. The inhibition efficiency increased with increase in Ser concentration, while it decreased with temperature, suggesting physical adsorption. Activation energies have been calculated in the absence and presence of various concentrations of Ser by measuring the temperature dependence of the corrosion rate obtained from the two methods employed. It was found that the activation energy in the presence of Ser is higher than that in bare HCl solution. The adsorptive behaviour of Ser followed Temkin-type isotherm. The standard free energy of adsorption was estimated to be −25 kJ mol −1 at 303 K. These results confirmed the occurrence of physical adsorption.

Complex formation of tris(2-aminoethyl)amine, Tren, with both Zn(II) and Cu(II) ions in aqueous solution was investigated spectroscopically by using 1H NMR and UV-visible titrations as well as electrochemically by using cyclic voltammetry. Analysis of the titration data indicated that the aqua complexes [(Tren)Zn(OH2)](ClO4)21 and [(Tren)Cu(OH2)](ClO4)22 deprotonate at pH = 10.6 and 9.7, forming the dinuclear bridged hydroxo species {[(Tren)Zn]2(μ-OH)}3+3 and {[(Tren)Cu]2(μ-OH)}3+4, respectively. The catalytic hydrolysis of the activated phosphate ester tris(p-nitrophenyl)phosphate (TNPP) by using these model complexes was examined and the released phenolate anions were determined by using spectroscopic and electroanalytical techniques.

The determination of glucose in microfluidic chips made of glass or PMMA was used as a model for the combination of an enzymatic reaction with the separation of compounds. It was based on the enzymatic oxidation of glucose and the amperometric detection of hydrogen peroxide. Real samples frequently contain compounds, such as ascorbic acid, which may interfere with quantitative glucose determinations. Thus, electrophoretic separation of specific from unspecific signals was envisaged by applying electric fields which are also used to control the flow of liquid via electroosmotic effects. Surface charge densities of the capillaries influence the electroosmotic flow (EOF). They are dependent on the chip material and on the adsorption of components from the background electrolyte. Reversal of the EOF after addition of cetyltrimethylammonium bromide (CTAB) and an increase in EOF after addition of sodium dodecylsulfate (SDS) were observed at lower surfactant concentrations with the PMMA chips rather than with the glass chips. For both chip materials these concentrations were below the critical micelle concentration. Effective separation of H2O2 and ascorbic acid was achieved with low CTAB concentrations, which lead to a reduction, but not to a reversal of the EOF. Reversal of the EOF by higher CTAB concentrations or the increase in cathodic EOF by SDS accelerated ascorbic acid transportation and reduced the differences in migration times. Thus, for the specific determination of glucose, glucose oxidase was added together with low CTAB concentrations to the background electrolyte. This avoided interference from ascorbic acid, and data obtained from the analysis of fruit juices showed a good correlation to data obtained from a reference method.

Glucose oxidase (GOD) was immobilized on screen-printed platinum electrodes by entrapment in a screen printable paste polymerized by irradiation with UV-light. The influences of different additives, in particular polymers and graphite, on the sensitivity and stability of the sensor and the permeability of the enzyme layer for a possible electrochemical interferent were investigated. The chosen additives were Gafquat 755N, poly-L-lysine, bovine serum albumin (BSA), sodium dodecylsulfate (SDS), polyethylene glycol (PEG), Nafion and graphite. All additives led to increases of glucose signals, i.e. improved the sensitivity of glucose detection with Gafquat 755N, poly-L-lysine, SDS and graphite showing the strongest influences with increases by a factor 4, 6.5, 5 and 10, respectively. Ascorbic acid was used as a model interferent showing the influence of the enzyme layer composition on the selectivity of the sensor. The addition of Gafquat 755N or poly-L-lysine led to higher signals not only for glucose, but also for ascorbic acid. SDS addition already reduced the influence of ascorbic acid, which was almost completely eliminated when Nafion (5%) and PEG (10%) were added. A comparable beneficial effect on the selectivity of the sensors was also observed for the addition of 0.5% graphite. Thus, the enzyme electrodes with PEG, Nafion or graphite as additives in the enzyme layer were applied to glucose determinations in food samples and samples obtained from E. coli cultivations.

Microfluidic systems are capillary networks of varying complexity fabricated originally in silicon, but nowadays in glass and polymeric substrates. Flow of liquid is mainly controlled by use of electroosmotic effects, i.e. application of electric fields, in addition to pressurized flow, i.e. application of pressure or vacuum. Because electroosmotic flow rates depend on the charge densities on the walls of capillaries, they are influenced by substrate material, fabrication processes, surface pretreatment procedures, and buffer additives. Microfluidic systems combine the properties of capillary electrophoretic systems and flow-through analytical systems, and thus biochemical analytical assays have been developed utilizing and integrating both aspects. Proteins, peptides, and nucleic acids can be separated because of their different electrophoretic mobility; detection is achieved with fluorescence detectors. For protein analysis, in particular, interfaces between microfluidic chips and mass spectrometers were developed. Further levels of integration of required sample-treatment steps were achieved by integration of protein digestion by immobilized trypsin and amplification of nucleic acids by the polymerase chain reaction. Kinetic constants of enzyme reactions were determined by adjusting different degrees of dilution of enzyme substrates or inhibitors within a single chip utilizing mainly the properties of controlled dosing and mixing liquids within a chip. For analysis of kinase reactions, however, a combination of a reaction step (enzyme with substrate and inhibitor) and a separation step (enzyme substrate and reaction product) was required. Microfluidic chips also enable separation of analytes from sample matrix constituents, which can interfere with quantitative determination, if they have different electrophoretic mobilities. In addition to analysis of nucleic acids and enzymes, immunoassays are the third group of analytical assays performed in microfluidic chips. They utilize either affinity capillary electrophoresis as a homogeneous assay format, or immobilized antigens or antibodies in heterogeneous assays with serial supply of reagents and washing solutions.

Adsorptive cathodic stripping voltammetry was used for the determination of furazolidone (FZ) and furaltadone (FD) in borax and phosphate buffers, respectively, using HMDE as working electrode. The influence of different factors upon the peak current response such as accumulation potential, scan rate, preconcentration time, pH and other variables was studied.

Cathodic stripping voltammetry was used to determine the antibacterial drug Nitrofurantoin in phosphate buffer (pH 5.5). The adsorptive peak was observed at −0.173 V vs. Ag/AgCl. The peak response was characterized with respect to pH, preconcetration time, possible interferences, deposition potential, supporting electrolytes and other variables. The obtained results were analyzed and the statistical parameters were calculated. Also the method was applied to determine the mentioned drug in pharmaceutical formulations and urine. The limit of detection was 1 × 10−9 mol dm−3.

Two new ligand-containing histidine based on N , N′ , N″ -tris(N-benzyl- l -histidinyl)tri(2-aminoethyl)amine, L 1 , namely N , N′ , N″ -tris[(1S)-2-methoxy-2-oxy-1-(1-benzylimidazol-4-ylmethyl)]nitrilotriacetamide L 2 and N , N′ , N″ -tris{N-benzyl-N-[N-benzyl-N-(N-benzyl- l -histidinyl)- l -histidinyl]- l -histidinyl}tri(2-aminoethyl)amine L 3 were prepared. Zinc(II) binding studies by these ligand systems were analyzed by means of potentiometric and 1 H NMR titrations in aqueous methanol (33 % v / v ). Subsequently their zinc(II) complexes [ L 1 Zn(H 2 O)](ClO 4 ) 2 ·HClO 4 ( 1 ), [ L 2 Zn(OH 2 )](ClO 4 ) 2 ·H 2 O ( 2 ), and ([ L 3 Zn 3 (H 2 O) 3 ](ClO 4 ) 6 ·3HClO 4 ·5H 2 O ( 3 ), respectively were synthesized and characterized. The reactivity of the trinuclear complex ( 3 ) toward the hydrolysis of the toxic organophosphate parathion was investigated and compared with that of the mononuclear reference complex ( 1 ). From the pH dependence of the apparent rate constants, and the deprotonation constant (p K a ) of the coordinated water molecules in ( 1 ), the active species were confirmed to be {[H L 1 Zn(OH)] 2+ /[ L 1 Zn(H 2 O)] 2+ } at pH 8.5. The trizinc complex ( 3 ) effects hydrolysis of parathion, with three times rate enhancement over the mononuclear ( 1 ), indicating that cooperative action of the three zinc centers is limited.

Enzymes are attractive tools in biotechnology for example for the production of complex organic compounds, in chemical analysis and medical diagnostics for the quantitative determination of specific compounds in complex matrices, but also in bioelectrochemistry as components of biofuel cells. In all application areas the use of immobilised enzymes is preferred over the use of enzyme solutions, as this allows multiple uses and easy handling of the enzyme. The results are bioreactors with immobilised enzymes and enzyme sensor systems, respectively.

A one-step procedure for the immobilization of glucose oxidase in fused-silica capillaries and in glass microchips was developed based on enzyme entrapment in a polyacrylamide-based monolithic column. The inner capillary surface was silanized with gamma-methacryloxypropyltrimethoxysilane (gamma-MAPS) to allow covalent binding of the gel to the surface. The composition of the polymer was optimized to prevent the formation of bubbles, allow liquid transportation by electroosmotic flow and to maintain the enzymatic activity. These requirements resulted in the addition of polyethylene glycol and poly(acrylic acid) to the acrylamide mixture. The gel containing the enzyme was formed in situ in the capillaries, respectively, in one channel of the microchip. In the microchip, it was limited to the sample injection channel by accordingly controlled silanization of the inner capillary surface. Glucose was detected via the amperometric determination of hydrogen peroxide. A linear correlation between signals and glucose concentration was observed from 0.05 to 1.1 mM glucose with a correlation coefficient of 0.999. The enzymatic monolithic microreactor showed no loss of activity during 8 h of continuous use and during storage in the running buffer at 4 degrees C for about 2 months. Interferents, such as ascorbic acid, were separated from the analyte electrophoretically, so that glucose could be quantified in diluted juices.