Main Group Chemistry

A novel transition metal chelate Cd(SCZ)₂Cl₂ (SCZ = semicarbazide) was synthesized from a known 1D metal-organic framework (MOF) Cd(SCZ)Cl₂ and fully characterized by elemental analysis and FTIR spectroscopy. Then the 1D MOF Cd(SCZ)Cl₂ was regained by adding CdCl₂ to the chelate Cd(SCZ)₂Cl₂. Single-crystal X-ray diffraction analysis revealed that Cd(SCZ)₂Cl₂ crystallizes in orthorhombic Pbcn space group. Differential scanning calorimetry (DSC) was applied to assess the thermal decomposition behavior of Cd(SCZ)₂Cl₂. The non-isothermal kinetics parameters of Cd(SCZ)₂Cl₂ were calculated by the methods of Kissinger and Ozawa-Doyle, respectively.

In this work a new magnetic nanocomposites based on Fe₃O₄-Hydrogel and Fe₃O₄@SiO₂-Hydrogel were synthesized. The poly(styrene-alt-maleic anhydride) was used as hydrogel compound. The hydrogel has the strong ability to remove some organic and inorganic compounds like methylene blue from water samples. Fe₃O₄ nanoparticles have the magnetic character that could help to the separation of hydrogel from the water after removal process by a magnet. The morphology of the hydrogel, Fe₃O₄, Fe₃O₄-Hydrogel and Fe₃O₄@SiO₂-Hydrogel was examined by scanning electron microscope (SEM). The structure of hydrogel and presence of the Fe₃O₄ and SiO₂ particles in the hydrogel nanocomposite was verified by FT-IR spectroscopy. The synthesized nanocomposites were used to remove the methylene blue from wastewater samples. Central Composite Design (CCD) and response surface method were used to optimize some parameters that affect the magnetic character, removal ability and removal efficiency, so the time of removal (minute), pH and the amount of hydrogel (mg) as important parameters were optimized by designing experiments. Determination of removal efficiency was done by spectrophotometric method. Results showed that the Fe₃O₄@SiO₂-Hydrogel had the more efficiency than Fe₃O₄-Hydrogel and the removal efficiency of methylene blue from water by synthesized Fe₃O₄@SiO₂-Hydrogel was between 50–95% that in the optimized condition it was almost 95%. Relative standard deviation (RSD) for 5 replicates the removal of methylene blue with synthesized sorbent was 4%.

In the present paper, the essential oil and the volatiles emitted in vivo by leaves of A. herba alba, which grows wild in center of Tunisia, were analyzed by GC-MS and SPME, respectively. The essential oil was characterized by the predominance of oxygenated monoterpenes (93.3%) with α-thujone as the major compound (45.5%) followed by β-thujone (11.4%), trans-sabinyl acetate (10.1%) and 1,8-cineole (7.4%). The SPME analyses showed that oxygenated monoterpenes were the most representative compounds (64.9%). The major ones were α-thujone (37.9%), germacrene D (16.5%), 1,8-cineole (8.4%) followed by β-thujone (7.8%). Moreover, different activities (antioxidant, antibacterial, allelopathic and insecticidal) of the leaf essential oil were investigated. The antioxidant activity was ascertained by evaluating its inhibitory effect against DPPH and ABTS. The results showed that the essential oil had a strong activity and it was more effective against the DPPH radical (IC₅₀ = 6μg/mL) than the ABTS radical (IC₅₀ = 40μg/mL). In antibacterial screening, it inhibited the growth of all bacteria tested except Salmonella anatum and Salmonella salamae which were resistant to this oil type. Staphylococcus aureus and Vibrio cholera were found to be extremely sensitive with the lowest MIC value (0.007 mg/mL). In addition, allelopathic activity was evaluated against Lactuca sativa and Raphanus sativus. Data showed that, with essential oil, seed germination was completely inhibited for both of them, suggesting a potent allelopathic potential for the evaluated oil. Insecticidal activity was investigated against Culex pipiens larvae and a weak activity (LC₅₀ 241.1 ppm) for this A. herba alba essential oil.

In this work, chitosan-g-itaconic acid copolymer nanocomposites containing nanoclay (1–5%, weight ratio) were synthesized using cerium (IV) ammonium nitrate as initiator. The optimum reaction conditions were identified as chitosan/itaconic acid monomer weight ratio of 3/9 and initiator concentration of 0.003 mol/L. These reaction conditions were used as preparation of chitosan-g-itaconic acid copolymer nanocomposites. XRD analysis and grafting percentage determination were used for characterization of nanocomposites. XRD patterns of nanocomposites indicate that clay sheets are exfoliated. Grafting percentages of chitosan-g-itaconic acid copolymers were determined as about 30%. Chitosan-g-itaconic acid nanocomposites were used for the removal of heavy metal ions from aqueous solutions. The results showed that the second-order kinetic model was suitable for the adsorption of Cu(II) and Pb(II) onto chitosan-g-itaconic acid nanocomposites. The equilibrium adsorption data have been evaluated using Langmuir, Freundlich, Temkin, Dubinin-Raduskevich and Redlich–Peterson models. Langmuir isotherm model (Type 1) and Redlich–Peterson isotherms are the best-fit models forthe adsorption process in this study.

The reaction of BAL with Sn(IV), SnCl₂·2H₂O, Pb(II), Ag(I), Cd(II) and Pd(II) gave water-insoluble solids where BAL coordinated using its two sulfur atoms, BAL(S,S)M, while anhydrous SnCl₂ gave BAL(O,S)Sn. Apart from the Sn(IV) and Ag(I) which should be monomeric, the structure of the other solids (monomeric or polymeric) could not be established. Indium(III) chloride did not react with either thiophenol or BAL in the absence of a base. In the presence of sodium hydroxide under 1:1:1, 1:2:2 and 1:3:3 molar ratios of InCl₃/PhSH/NaOH, the products incorporated the formed sodium chloride and In(SPh)₃ was isolated after aqueous work up in the 1:3:3 case. Thallium(III) aceteate gave Tl-SPh and PhSSPh. Thallium(I) acetate and thallium(I) fluoride also gave Tl-SPh in 100% and 75% yields, respectively. The lower yields with TlF is attributed to the non thiophilic HTlF₂ formed during the reaction. Theoretical calculations of TlF, (TlF)₂ and TlF₂^- revealed a novel structure of (TlF)₂ and shed light to the non thiophilicity of TlF₂^-. Thallium(I) acetate and BAL gave the expected bis salt while the reactions of TlF under various stoichiometries of BAL:TlF were complicated. Summarizing these and previous results it seems that BAL cannot detoxify heavy metal cations by forming water soluble complexes.

We perform density functional calculations on the ground state geometries of VO_n (n = 1–5) complexes and analyze their stability against dissociation to O atom and O₂ molecule in neutral as well as anionic forms. It is shown that a V binds with four O atoms stably such that the maximum possible oxidation state of V can be as high as +7. The electron affinity of VO_n suggests that these species behave as superhalogen for n≥3, which become as large as 4.52 eV for n = 5. The interaction of VO_n superhalogen with appropriate alkali metal is stronger than traditional alkali halides. This is exemplified by formation of stable NaVO₃ complex compound by interacting alkali Na atom with VO₃ superhalogen. This finding demonstrates that VO_n superhalogens form a new class of salt,which is relatively more stable than NaCl molecule.

Pandermite (Ca₄B₁₀O₁₉ 7H₂O) can be defined as a type of calcium borate hydrate which generally founds in Turkey and USA. It has been identified by using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Scanning electron microscope (SEM) during dehydration process. Thermal gravimetry and differential thermal gravimetry (TG/DTG) methods have been applied to investigate the thermal dehydration kinetic of pandermite. The results showed that it lost its crystal water via three-step process approximately between 280°C and 550°C temperatures. Activation energies (E_a . ) were found as 98.83, 136.86 and 391.24 kJ using Ozawa–Flynn–Wall (OFW) model; 89.82, 133.16 and 399.01 kJ using Kissinger–Akahira–Sunose (KAS) model; and 140.78, 131.01 and 486.22 kJ using Kissinger non-isothermal kinetic model for steps 1, 2 and 3, respectively. At the end of the dehydration process, Pandermite lost its water content and it decomposed to CaB₂O₄ (powder diffraction file number: 00-009-0247) and B₂O₃ (powder diffraction file number: 01-072-0626) occurred.

In this study by using the precursors of Zn₅(CO₃)₂·(OH)₆ and H₃BO₃, Zn₃B₆O₁₂·3.5H₂O type of a zinc borate compound is synthesised. A green sonochemical method of ultrasonic irradiation is used with several parameters such as; reaction temperature and reaction time. Synthesized zinc borate compounds are characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy techniques. Then the surface morphologies are investigated by scanning electron microscopy (SEM). From the XRD results, the minimum reaction conditions to successfully synthesize Zn₃B₆O₁₂·3.5H₂O were found as 80°C – 50 min, 85°C – 40 min, 90°C – 40 min. The FT-IR and Raman spectroscopies showed that the synthesized products characteristic bands were in good agreement with the bands of boron compounds. SEM morphological analyses showed that synthesized compounds were in particularly thorn like and tubular with the particle sizes between 77– 296 nm. Also the reaction yields were calculated between 90.34– 97.12%.