A novel approach to produce monodisperse hollow pure silica spheres

In this work, we report an efficient method to produce pure hollow silica spheres (HSS) using phenyltrimethoxysilane (PTMS) compound. The production of HSS was carried out via hydrolysis of PTMS in the aqueous media and followed by a condensation reaction to form silica spheres with phenyl groups. The product was then calcined to remove phenyl groups and obtain pure silica spheres with >95% fine structure. The chemical nature of pure silica was confirmed by Fourier transforms infrared spectroscopy. The calcined HSS were stable beyond the temperature of 900 °C as confirmed by thermal gravimetric analysis (TGA). The calcined spheres preserved their spherical appearance and hollow core as shown by SEM and TEM micrographs. Interestingly, the average size of the spheres was reduced significantly after calcination from 760 to 510 nm, confirming further the removal of phenyl groups. The calcined HSS offered much higher surface area (A_s) when analysed by BET; A_s for calcined product was ～406 and mere ～4.8 m²/g for uncalcined HSS. Finally, drug release study of cisplatin/HSS showed over 45% of steady cumulative release for 72 h. The prepared HSS can be dispersed in water opening the possibility of many novel bio/non-bio applications.     

Synthesis,characterization, and cytotoxic activity studies of new N4O complexes derived from 2-({3-[2-morpholinoethylamino]-N3-([pyridine-2-yl]methyl) propylimino} methyl)phenol

A new unsymmetrical five-coordinate Schiff base ligand (HL) with an N₄O donor set ( 2 ) has been prepared by condensation of N1-(2-morpholinoethyl)-N1-([pyridine-2-yl]methyl)propane-1,3-diamine with 2-hydroxy-benzaldehyde. Metal complexes [ML]ⁿ⁺ (M = Zn²⁺, Cd²⁺, Mn²⁺, Cu²⁺, Ni²⁺, Ag⁺, Fe³⁺, and Co²⁺ ( 3–10 ) were synthesized by the reaction of the ligand and metal salts in ethanol. The resulting products were characterized by elemental analyses, infrared, ¹H and ¹³C nuclear magnetic resonance spectra (in the case of Cd and Zn complexes), UV–Vis, electrospray ionization-mass spectrometric, and conductivity measurements. The structure of the complexes [ZnL](ClO₄) ( 3 ), [CdL](ClO₄) ( 4 ), and [CuL](ClO₄) ( 7 ) has been determined by single-crystal X-ray diffraction analysis. The metal complexes were determined to have a distorted trigonal bipyramidal (Zn and Cd) or a distorted square pyramidal (Cu) geometry. The cytotoxic potential of each compound (1–10) against MCF-7 and MDA-MB-231 (breast cancer cells), PC-3 (prostate cancer cells), and WI-38 human normal lung fibroblast cells was evaluated using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide) assay. Compounds 1, 2, and 10 did not display any activity toward any cell line tested. None of the compounds except compound 8 was cytotoxic toward PC-3. Compounds 4 and 8 showed the highest cytotoxic activity against the MCF-7 and MDA-MB-231 cell lines. Because compounds 3, 6, and 9 have similar half-maximal inhibitory concentration values against cancer cells and normal cells, these compounds displayed poor selectivity between cancer and normal cells. More importantly, it was observed that compound 5 acts differently toward different types of cell lines. For example, it displays lower cytotoxicity against the WI-38 normal cell line than it does against the MDA-MB-231 cell line.     

EPR study of Cu(2+)-doped tetraaqua-di(nicotinamide)Co(II) saccharinate single crystals

The electron paramagnetic resonance spectra of Cu(2+) impurities in [Co(nicotinamide)(2)(H(2)O)(4)](saccharinate)(2) single crystals have been studied at ambient temperature in three mutually perpendicular planes. The angular variation of the spectra shows that the Cu(2+) ion substitutes the Co(2+) site in the lattice. The EPR spectra of Cu(2+) ions are characteristic of tetragonally elongated octahedral site. The spin-Hamiltonien parameters were obtained from the single crystal EPR analysis. The ground-state wave function of Cu(2+) ion in the lattice has been constructed.     

Elucidating the Stereochemistry of Enzymatic Benzylsuccinate Synthesis with Chirally Labeled Toluene

Benzylsuccinate synthase is a glycyl radical enzyme that initiates anaerobic toluene metabolism by adding fumarate to the methyl group of toluene to yield (R)‐benzylsuccinate. To investigate whether the reaction occurs with retention or inversion of configuration at the methyl group of toluene, we synthesized both enantiomers of chiral toluene with all three H isotopes in their methyl groups. The chiral toluenes were converted into benzylsuccinates preferentially containing ²H and ³H at their benzylic C atoms, owing to a kinetic isotope effect favoring hydrogen abstraction from the methyl groups. The configuration of the products was analyzed by enzymatic CoA‐thioester synthesis and stereospecific oxidation using enzymes involved in benzylsuccinate degradation. Assessment of the configurations of the benzylsuccinate isomers based on loss or retention of tritium showed that inversion of configuration at the methyl group occurs when the chiral toluenes react with fumarate.     

Surface and chemical characteristics of platinum modified activated carbon electrodes and their electrochemical performance

Platinum (Pt) loaded activated carbons (ACs) were synthesized by the thermal decomposition of platinum (II) acetylacetonate (Pt(acac)₂) over chemically activated glucose-based biochar. The effect of Pt loading on surface area, pore characteristics, surface chemistry, chemical structure, and surface morphology were determined by various techniques. XPS studies proved the presence of metallic Pt⁰ on the AC surface. The graphitization degree of Pt loaded ACs were increased with the loaded Pt⁰ amount. The electrochemical performance of the Pt-loaded ACs (Pt@AC) was determined not only by the conventional three-electrode system but also by packaged supercapacitors in CR2032 casings. The capacitive performance of Pt@AC electrodes was investigated via cyclic voltammetry (CV), galvanostatic charge-discharge curves (GCD), and impedance spectroscopy (EIS). It was found that the Pt loading increased the specific capacitance from 51 F/g to 100 F/g. The ESR drop of the packaged cell decreased with the Pt loading due to the fast flow of charge through the conductive pathways. The results showed that the surface chemistry is more dominant than the surface area for determining the capacitive performance of Pt loaded AC-based packaged supercapacitors.     

The generalization of the generalized Al-Oboudi differential operator

In this paper, firstly we define the generalization of the generalized Al-Oboudi differential operator. Then we also define new classes of analytic and p-valently starlike and convex functions with complex order by means of this new general differential operator. Our main purpose is to determine coefficient bounds for functions in certain subclasses of this classes, which are introduced here by means of a family of nonhomogeneous Cauchy-Euler differential equations. Relevant connections of some of the results obtained with those in earlier works are also provided.     

Use of ionic liquid based chitosan as sorbent for preconcentration of fluoroquinolones in milk,egg, fish,bovine, and chicken meat samples by solid phase extraction prior to HPLC determination

The possibility of using ionic liquid based chitosan sorbent for the separation and preconcentration of fluoroquinolone antibiotics (marbofloxacin, enoxacin, ofloxacin, ciprofloxacin, and enrofloxacin) has been studied. For this reason, different ionic liquids were prepared and coated on the chitosan sorbent. The conditions of the preconcentration of fluoroquinolones on a microcolumn have been optimized and the extraction efficiencies of the prepared sorbents have been compared. The compounds were eluted with 5 mL of 20% NH₃ (v/v, MeOH) solution and determined by HPLC with diode array and fluorescence detector. The limits of detection were found as 4.23 µ g L^?1 for marbofloxacin, and 1.09 µg L^?1 for enoxacin; 3.23 × 10^?3 µg L^?1 for ofloxacin; 8.39 × 10^?3 µg L^?1 for ciprofloxacin; and 19.50 × 10^?3 µg L^?1 for enrofloxacin. The developed method was applied for the analysis of fluoroquinolone in milk, egg, fish, bovine, and chicken samples and the recoveries were obtained in the range 70–100%.     

Synthesis and proton conductivity studies of azole functional organic electrolytes

As an attempt to produce azole functional proton conductors, organic electrolytes with triazole and tetrazole functional groups were synthesized via substitution reaction of 1,3,5-benzenetricarbonyl trichloride with aminotriazole and aminotetrazole. The samples were doped with triflic acid with molar ratios of 0.25 and 0.50. FTIR, nuclear magnetic resonance (NMR), and elemental analysis were used to characterize the resulting materials. Thermogravimetric analysis showed that the samples are thermally stable up to 150?°C. The effect of acid doping on proton conductivity was investigated with impedance spectrometer. Both pure samples and the doped ones revealed high proton conductivity. In anhydrous conditions (TMA)-TriTA_0.50 and TMA-TetTA_0.50 have proton conductivities of 1.8 and 19?mS/cm at 150?°C, respectively. Solid-state NMR studies revealed that there are three different types of hydrogen-bonded acidic proton in the systems. Moreover, these different types of acidic protons present at different ratio in triazole and tetrazole systems.