Modified carbon paste ion selective electrode for determining Cr(iii) ions in aqueous solutions and some real samples using tetragonal zirconia nanoparticles.

Tetragonal zirconia (t-ZrO2) nanoparticles (ionophore) are used in newly designed and improved ion selective electrodes for chromium ion detection as an alternative, low-cost, high-precision, and selectivity method. Tetragonal zirconia nanoparticles were synthesized using a modified co-precipitation technique and calcined at 1000 °C for an hour. The phase composition, surface area, microstructure, pore size and particle size of synthesized t-ZrO2 nanoparticles were examined using the X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscope (TEM) and scanning electron microscopy (SEM) attached with an EDAX unit, respectively. Results from XRD showed that the t-zirconia was synthesized and have nanocrystallites size about 20.2 nm. The nano size of t-ZrO2 was confirmed by the SEM and TEM (the particle size between 26.48 and 40.4 nm), the mesoporous character (average pore size about 4.868 nm) and large surface area (76.2802 m2 g-1) was confirmed by BET analysis. The paste composition with 67.3 : 30.5 : 2.7 (wt%) graphite, t-ZrO2, and TCP, respectively, exhibited the best results. With a detection limit of 1.0 × 10-8 mol L-1, the electrode displayed a good Nernstian slope of 19.50 ± 0.10 mV decade-1 over the concentration range from 1.0 × 10-2 to 1.0 × 10-8 mol L-1 of Cr(iii) ions. The built-in sensor displayed a quick response time (7 s), was highly thermally stable in the range of 10 to 60 °C without departing from Nernstian behaviour and could be used for about 60 days in the pH range of 2.0 to 6.0. The electrode demonstrated excellent selectivity for the Cr(iii) ion towards a variety of metal ions. For chromium ion determination, numerous spiked real samples, including honey, water, tea, coffee, milk, cheese, and cosmetics, were used. Validation methods were used, and the results showed that there is no significant difference between the two methods (ICP and ISE) at a 95% confidence level. In several real water samples, the estimated limits of detection, limits of quantification, percent recovery, standard deviation, and relative standard deviation showed the effectiveness of the proposed electrode in the potentiometric detection of Cr(iii) ions.

Coordination modes of bidentate lornoxicam drug with some transition metal ions. Synthesis, characterization and in vitro antimicrobial and antibreastic cancer activity studies.

The NSAID lornoxicam (LOR) drug was used for complex formation reactions with different metal salts like Cr(III), Mn(II), Fe(III) and Ni(II) chlorides and Fe(II), Co(II), Cu(II) and Zn(II) borates. Mononuclear complexes of these metals are obtained that coordinated to NO sites of LOR ligand molecule. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, IR, UV-Vis, (1)H NMR, mass, electronic spectra, magnetic susceptibility and ESR spectral studies, conductivity measurements, thermogravimetric analyses (TG-DTG) and further confirmed by X-ray powder diffraction. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. The data show that the complexes have composition of ML2 type except for Fe(II) where the type is [ML3]. The electronic absorption spectral data of the complexes suggest an octahedral geometry around the central metal ion for all the complexes. The antimicrobial data reveals that LOR ligand in solution show inhibition capacity less or sometimes more than the corresponding complexes against all the species under study. In order to establish their future potential in biomedical applications, anticancer evaluation studies against standard breast cancer cell lines (MCF7) was performed using different concentrations. The obtained results indicate high inhibition activity for Cr(III), Fe(II) and Cu(II) complexes against breast cancer cell line (MCF7) and recommends them for testing as antitumor agents.

Ligational behaviour of lomefloxacin drug towards Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO(2)(VI) ions: synthesis, structural characterization and biological activity studies.

Nine new mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Th(IV) and UO(2)(VI) complexes of lomefloxacin drug were synthesized. The structures of these complexes were elucidated by elemental analyses, IR, XRD, UV-vis, (1)H NMR as well as conductivity and magnetic susceptibility measurements and thermal analyses. The dissociation constants of lomefloxacin and stability constants of its binary complexes have been determined spectrophotometrically in aqueous solution at 25±1°C and at 0.1 M KNO(3) ionic strength. The discussion of the outcome data of the prepared complexes indicate that the lomefloxacin ligand behaves as a neutral bidentate ligand through OO coordination sites and coordinated to the metal ions via the carbonyl oxygen and protonated carboxylic oxygen with 1:1 (metal:ligand) stoichiometry for all complexes. The molar conductance measurements proved that the complexes are electrolytes. The powder XRD study reflects the crystalline nature for the investigated ligand and its complexes except Mn(II), Zn(II) and UO(2)(II). The geometrical structures of these complexes are found to be octahedral. The thermal behaviour of these chelates is studied where the hydrated complexes lose water molecules of hydration in the first steps followed by decomposition of the anions, coordinated water and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated using Coats-Redfern and Horowitz-Metzger methods. A comparative study of the inhibition zones of the ligand and its metal complexes indicates that metal complexes exhibit higher antibacterial effect against one or more bacterial species than the free LFX ligand. The antifungal and anticancer activities were also tested. The antifungal effect of almost metal complexes is higher than the free ligand. LFX, [Co(LFX)(H(2)O)(4)]·Cl(2) and [Zn(LFX)(H(2)O)(4)]·Cl(2) were found to be very active with IC50 values 14, 11.2 and 43.1, respectively. While, other complexes had been found to be inactive at lower concentration than 100 µg/ml.