A spectroscopic and imaging investigation of sporopollenin-metal interactions

The main objective has been the determination of the nature of the interaction of metal complexes and salts with the surface of sporopollenin exine capsules (SEC) and other naturally occurring spore exines. These natural materials derived from plant pollen and spores can interact with the inorganic compounds via the formation of coordination bonds and can impart unusual properties. This makes them ideal materials for investigation as they can be used in a wide variety of applications including catalysis, metal remediation, imaging and biological delivery. Although there have been many studies using brown SECs, the focus of this work has been on bleached SECs as the paler colour enables the use of a wider variety of spectroscopic techniques. The first row transition metals copper, iron, nickel, and zinc were used and a selection of spectroscopic techniques (IR, Raman, ICP-OES, UV-Vis, NMR, EPR, Mössbauer and X-ray absorption spectroscopy) were employed to characterise the complexes formed between the metals and the brown and white SECs. Metal loadings of 0.5 to 10 wt% were observed for all the metals and both the brown and bleached SECs. The higher loadings were observed for complexes derived from acetate salts for copper, nickel and zinc. IR spectroscopy of the SECs revealed the presence of aliphatic chains and hydroxyls, aliphatic carbons, carbonyls, unsaturation, ester and ether groups. For the copper, nickel and zinc complexes the IR spectra showed the presence of νCO modes indicating the mode of coordination, and in the acetate complexes there were a significant difference in the spectrum indicating the presence of bound acetate. The IR spectra of the iron complexes were different indicating the presence of a different structural motif. The UV-vis spectra displayed the characteristic features of metal(II) for copper, nickel and zinc, with the spectra of the complexes prepared from chloride and nitrate solutions being essentially identical, but different to that from the acetate solution. There were slight differences between all the spectra of the iron-BL-SEC complexes, with the complex derived from SEC and solution of (NH4)Fe(SO4)2 presenting the highest intensity peak. The 13C NMR solid state spectra of the brown and bleached SECs, as well as those of the zinc complexes showed peaks characteristic of aliphatic, olefinic and aromatic carbon, C-O, carboxylic acid and ester groups. For the zinc acetate with BL-SECs was different in the 35 – 10 ppm aliphatic region compared to that of zinc nitrate and zinc chloride with BL-SEC. However, the spectra were similar for all zinc salts with BR-SECs. The metal K-edge EXAFS data from the nickel and zinc complexes were more similar to the copper data rather than the iron data, indicating the presence of mononuclear octahedral metal complexes for nickel and zinc. For copper, the EXAFS data indicated the presence of a Jahn-Teller distortion for copper, which was confirmed by EPR spectroscopy. In the case of iron the EXAFS data indicated the formation of small oxide or oxyhydroxide particles. The metal K-edge XANES data confirmed the presence of Cu(II), Ni(II) and Zn(II), but indicated that in the case of iron, this was present as Fe(III), which was also consistent with the 57Fe Mössbauer data. XRF imaging data using synchrotron radiation has shown that the metal distribution in the copper, nickel and zinc complexes is very closely associated with the underlying physical structure of the SEC. The conclusion from all the spectroscopic data is that the most likely source of coordination of the copper, nickel and zinc metals are the carboxylate groups in the sporopollenin structure resulting in monomeric complexes on the sporopollenin surface. The structures of the chloride and nitrate complexes are very similar, but in the case of acetate there is evidence for the presence of acetate ligands in the coordination environment. The higher metal loadings observed for the acetate complexes can be explained by this as the metal does not require so many ligand groups in close proximity on the SEC surface. In the case of iron, the structures appear to be different, and are based on very small clusters of iron oxide or oxyhydroxide particles attached to the SEC surface

Synthesis, characterization, DFT calculations and biological activity of new Schiff base complexes

Schiff bases ligand (HL) was produced by condensing 4-aminobenzohydrazide with N-(4-chlorophenyl)-2-(4-formylphenoxy)acetamide. Cobalt (II), nickel (II), and copper (II) acetate and ligand are reacted to form 1:1 complexes. By using electronic spectra, magnetic susceptibility measurements, infrared data from 1H NMR, and XRD studies, the ligand and its metal complexes have been characterized. According to the spectrum data, the ligand functions as a monobasic bidentate, coordinating with the nitrogen atom of azomethine (−CN−) group and the oxygen atom of carbonyl group in enol form. An octahedral structure has been proposed for Co(II), Ni(II), and Cu(II) complexes according to magnetic and electronic spectrum analysis. Using the DFT method, the computational investigations of the ligand and its metal complexes showed the bond lengths, bond angles, and quantum chemical parameters. To determine the thermal stability and mode of thermal degradation of hydrazone ligand and its complexes, thermogravimetric analysis was approved out on the samples. Two calculated method, Horowitz-Metzger and Coats-Redfern, were used to calculate the characteristics of the composites' thermal degradation mechanisms at each step, including their breakdown kinetics. The ligand and its complexes were investigated for their cytotoxicity in vitro compared to human amnion (WISH) and epitheliod carcinoma (Hela). The Ni(II) complex showed highly inhibition against (WISH) growth (IC50 = 18.28±1.8 μM) with relationship to the produced chemicals and other common medications. The interaction between the ligand and its complexes with the genetic tumor (3hb5) receptor was examined using docking experiments

Metal Chelates of Sulfafurazole Azo Dye Derivative: Synthesis, Structure Affirmation, Antimicrobial, Antitumor, DNA Binding, and Molecular Docking Simulation

A series of divalent and one trivalent metal chelates of the azo ligand resulting from coupling of sulfafurazole diazonium chloride with resorcinol have been designed and synthesized. Structure investigation of the isolated chelates have been achieved by applying spectroscopic and analytical tools which collaborated to assure the formation of the metal chelates in the molar ratios of 1L: 1M for Ni(II), Co(II), and Fe(III) chelates, where Cu(II) and Zn(II) complexes formed in the ratio 2L : 1M. The geometrical arrangement around the metal canters was concluded from UV-Vis spectra to be octahedral for all metal chelates. The attachment of the ligand to the metal ions took place through the azo group nitrogen and o-hydroxyl oxygen through proton displacement leading to the ligand being in monobasic bidentate binding mode. Antimicrobial and antitumor activities of the interested compounds have been evaluated against alternative microorganisms and cancer cells, respectively, in a trial to investigate their extent of activity in addition to docking studies. The mode of interaction of the compounds with SS-DNA has been examined by UV-Vis spectra and viscosity studies

Dependence of the Magnetization Process on the Thickness of Fe70Pd30 Nanostructured Thin Film

Fe–Pd magnetic shape-memory alloys are of major importance for microsystem applications due to their magnetically driven large reversible strains under moderate stresses. In this context, we focus on the synthesis of nanostructured Fe70Pd30 shape-memory alloy antidot array thin films with different layer thicknesses in the range from 20 nm to 80 nm, deposited onto nanostructured alumina membranes. A significant change in the magnetization process of nanostructured samples was detected by varying the layer thickness. The in-plane coercivity for the antidot array samples increased with decreasing layer thickness, whereas for non-patterned films the coercive field decreased. Anomalous coercivity dependence with temperature was detected for thinner antidot array samples, observing a critical temperature at which the in-plane coercivity behavior changed. A significant reduction in the Curie temperature for antidot samples with thinner layer thicknesses was observed. We attribute these effects to complex magnetization reversal processes and the three-dimensional magnetization profile induced by the nanoholes. These findings could be of major interest in the development of novel magnetic sensors and thermo-magnetic recording patterned media based on template-assisted deposition techniques

Evaluation of tetracycline removal by magnetic metal organic framework from aqueous solutions: Adsorption isotherm, kinetics, thermodynamics, and Box-Behnken design optimization

In our current research, an intriguing magnetic nano sorbent Fe3O4@Zr-MOF was synthesized in the lab. We used this adsorbent for successfully removing tetracycline (TC) from water. We performed a number of experiments and studies to further support this, including the following: vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller surface area (BET). Our studies have determined that the Fe3O4@Zr-MOF boasts a considerable surface area of 868 m2/g with the highest adsorption capacity (qmax) of 942.12 mg/g. Study the factors that effect on adsorption process such as pH, TC concentration, adsorbent dose, and temperature. The adsorption isotherm was fitted to the Langmuir equation, whereas the kinetic isotherm to the pseudo-second-order equation. The adsorption process was chemisorption as well as the adsorption energy was 20 kJ/mol. Adsorption thermodynamics indicated that the adsorption process was both endothermic and spontaneous. As temperatures increased, the amounts of materials absorbed also increased. The Fe3O4@Zr-MOF has magnetic properties as it easily to remove from the solution after adsorption process. The adsorbent was used for five cycles with high efficiency and without change in the chemical composition as well as the XRD was the same before and after reusability. The mechanism of the interaction between Fe3O4@Zr-MOF and TC was expected on: Electrostatic interaction, π-π interaction, hydrogen bonding, and pore filling. The adsorption results were optimized using Box Behnken-design (BBD)