Intermetallic Competition in the Fragmentation of Trimetallic Au–Zn–Alkali Complexes

Cationization is a valuable tool to enable mass spectrometric studies on neutral transition‐metal complexes (e.g., homogenous catalysts). However, knowledge of potential impacts on the molecular structure and catalytic reactivity induced by the cationization is indispensable to extract information about the neutral complex. In this study, we cationize a bimetallic complex [AuZnCl₃] with alkali metal ions (M⁺) and investigate the charged adducts [AuZnCl₃M]⁺ by electrospray ionization mass spectrometry (ESI‐MS). Infrared multiple photon dissociation (IR‐MPD) in combination with density functional theory (DFT) calculations reveal a μ³ binding motif of all alkali ions to the three chlorido ligands. The cationization induces a reorientation of the organic backbone. Collision‐induced dissociation (CID) studies reveal switches of fragmentation channels by the alkali ion and by the CID amplitude. The Li⁺ and Na⁺ adducts prefer the sole loss of ZnCl₂, whereas the K⁺, Rb⁺, and Cs⁺ adducts preferably split off MCl₂ZnCl. Calculated energetics along the fragmentation coordinate profiles allow us to interpret the experimental findings to a level of subtle details. The Zn²⁺ cation wins the competition for the nitrogen coordination sites against K⁺, Rb⁺, and Cs⁺ , but it loses against Li⁺ and Na⁺ in a remarkable deviation from a naive hard and soft acids and bases (HSAB) concept. The computations indicate expulsion of MCl₂ZnCl rather than of MCl and ZnCl₂.     

Accurate and simple determination of oxcarbazepine in human plasma and urine samples using switchable-hydrophilicity solvent in GC–MS

This work presents a sensitive and rapid analytical method for the determination of oxcarbazepine in human plasma and urine samples. A vortex-assisted switchable hydrophilicity solvent-based liquid phase microextraction (VA–SHS–LPME) was used to preconcentrate oxcarbazepine from the samples before the determination by gas chromatography mass spectrometry. The switchable hydrophilicity solvent was synthesized by protonating N,N-dimethylbenzylamine with carbon dioxide to make it totally miscible with an equivalent volume of water. Parameters of the VA–SHS–LPME method including volume of switchable hydrophilicity solvent, concentration/volume of sodium hydroxide and vortex period were systematically optimized. Under the optimum conditions, good linearity ranging from 27.03 to 353.47 μg/kg was obtained for the analyte. Limit of detection and quantitation values were found to be 6.2 and 21 μg/kg (mass base), respectively. The relative standard deviation was calculated as 6.9% for six replicate measurements of the lowest concentration of the calibration plot. Satisfactory recovery results were calculated in the range of 97–100% for human plasma and urine samples spiked at five different concentrations.     

Synthesis,Characterization, and Theoretical Calculation of New Azo Dyes Derived from [1,5‐a]Pyrimidine‐5‐one Having Solvatochromic Properties

7‐Amino‐3‐phenylazo‐2‐methyl‐4H‐pyrazolo[1,5‐a]pyrimidine‐5‐one ( 3 ) was synthesized by the reaction of 5‐amino‐3‐methyl‐4‐phenylazo‐1H‐pyrazole and 2‐aminobenzothiazole with ethyl cyanoacetate in acetic acid at 150°C. Four novel heterocyclic azo disperse dyes were obtained by the coupling of heterocyclic amines‐based diazonium chloride with compound 3 . They were purified and characterized by elemental analysis, FTIR, and ¹H NMR. Furthermore, solvatochromic behaviors of related dyes were studied in detail by using ultraviolet–visible absorption spectrometer. The experimental data were supported by density functional theory using b3lyp/cc‐pvtz level calculations, and a detailed analysis of predicted tautomeric structures was made.     

Arsenic speciation in water and biota samples at trace levels by ion chromatography inductively coupled plasma-mass spectrometry

A sensitive, reliable, simple and rapid analytical method was developed for the determination of arsenite [As(III)], arsenate [As(V)] and arsenobetaine (AsB) species using ion chromatography combined with inductively coupled plasma-mass spectrometry (IC-ICP-MS). Inorganic and organic arsenic species were separated with an anion exchange column (Dionex AS9) and a 50 mM sodium bicarbonate mobile phase (pH 10) at a flow rate of 1.0 mL min^?1. %RSD values were found to be lower than 5.1% for all arsenic species. The limits of detection (LOD) obtained for As(III), As(V) and AsB were 16.5 ng L^?1, 14.1 ng L^?1 and 6.2 ng L^?1, respectively. The developed analytical method was tested using AsB certified reference material (NMIJ CRM 7901-a), and spring water certified reference material (UME CRM 1201) for accuracy check. This method was applied for the quantitative determination of arsenic species in different water samples and chicken samples as a solid matrix.     

The reaction of hexachlorocyclotriphosphazatriene with P-aminophenol

The reaction of hexachlorocyclotriphosphazatriene (1) with p-aminophenol (2) produced two new products: the open chain compound N₃P₃Cl₅(NHC₆H₄OH) (3), and the bridged compound N₃P₃Cl₅(NHC₆H₄O)N₃P₃Cl₅(4). The compounds 3 and 4 were separated and characterized by elemental analysis, massspectrometry and NMR spectroscopy. The molecular structures of compounds 3 and 4 were determined by X-ray crystallography. Compound 3 is the first example of cyclotriphosphazene including (p-hydroxyphenyl) amino group and compound 4 was the first example of the N-substituted p-aminophenoxy group with cyclotriphosphazene.     

Effects of solvent casted poly (lactic acid)/poly(ethylene glycol)/paraben derivative triazine films on antibacterial performance and cytotoxicity

A series of poly(lactic acid) (PLA) films that including fully paraben substituted triazine derivatives having anti-bacterial properties have been prepared by utilizing the solvent-casting method. PLA as biodegradable polymer, poly(ethylene glycol) (PEG) as a plasticizing agent and s-triazine molecules (TA01, TA02, TA03, TA04, and TA05) behaving as an anti-bacterial component have been utilized in the experiments. The influence of TA compounds on the antibacterial performance of PLA/PEG films was investigated for the first time against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria via the contact active method. TA01-03-05 incorporated PLA/PEG films gave the best results against E.coli bacteria and log10 reductions of these films were 0.78, 0.64, and 0.65 respectively. The effect of TA compounds on the cell viability was investigated against cancer and non-cancerous cell lines using an MTS assay. The results showed that TA compounds had a positive effect on cell growth in non-cancerous cells, while they had a negative effect on cell growth in cancer cells. Furthermore, the addition of TA considerably increased the decomposition temperatures from 349° to 361° and char yield from 0.65 for PLA/PEG film to 2.3 for PLA/PEG/TA05. All of the films had good transparency and low opacity which was 7.2 for pure PLA used for control and the maximum opacity value was 11.2 observed for PLA/PEG/01. TA03 and TA04 caused a decrement of water vapor permission when compared to PLA/PEG films from 1439 to 749 and 664. It was also observed that pure PLA/PEG film lost weight rapidly over time during degradation tests. On the other hand, weight loss wasn't observed in PLA/PEG/TA films. This study focused on demonstrating the use of our new, flexible PLA/PEG derivatives in food and medical packaging.     

Multiplication operators on Cesàro second order function spaces

Positivity - In this article, we investigate bounded, invertible and compact multiplication operators on the second order Cesàro function spaces.     

Determination of sodium migration in sol-gel deposited titania films on soda-lime glass with r.f. glow discharge optical emission spectroscopy

Transparent TiO₂ films were produced via sol-gel spin and dip-coating techniques. Soda-lime glass (SLG) and SiO₂ precoated glass were used as substrates. The thin films were characterized by X-ray diffraction (XRD), X-ray reflectometry (XRR), optical profilometer and glow discharge optical emission spectroscopy (GD-OES). Na migration was detected in the amorphous TiO₂ films which are deposited on SLG substrates. In order to prevent sodium migration a barrier layer was introduced between TiO₂ film and glass. The beneficial role of this barrier layer on alkali migration is verified and the mechanism of prevention of migration is proposed relying on the results of GD-OES depth profile measurements.     

On the performance of West’s bubble test: A simulation approach

In this research we examine the ability of West’s bubble test [1] in detecting speculative bubbles using Brock’s (1982) [2] intertemporal general equilibrium model of asset pricing as the basis for a simulation study. In this setting, (1) the economy, by construction is efficient and produces the maximally possible amount of welfare for society, and (2) asset prices reflect the utility-maximizing behavior of consumers and the profit-maximizing behavior of firms. We find that the West’s bubble test flag as “bubbles” in the simulated data yet the data is produced from an economy in which markets are efficient in welfare production.