A combination of dispersive liquid–liquid microextraction and surface plasmon resonance sensing of gold nanoparticles for the determination of ziram pesticide

We have developed a reliable, fast, and highly sensitive analytical method utilizing dispersive liquid–liquid microextraction and gold nanoparticles probes for ziram (zinc bis(dimethyldithiocarbamate)) determination. The method is based on the in situ formation of gold nanoparticles in carbon tetrachloride as an organic phase. It was found that the trace levels of ziram influenced the formation of gold nanoparticles, leading to absorbance change of a sedimented phase. The results of the colorimetric ziram determination were in the concentration range of 0.12–2.52 ng/mL with a limit of detection of 0.06 ng/mL. The formation of the stable and dispersed gold nanoparticles in the organic phase provides a good precision for dispersive liquid–liquid microextraction method, resulting in the relative standard deviation of 3.8 and 1.2% for 0.56 and 1.58 ng/mL of ziram, respectively. This method has been successfully used for the ziram determination in samples of well and river water, soil, potato, carrot, wheat, and paddy soil.     

Head–Tail Asymmetry as the Determining Factor in the Formation of Polymer Cubosomes or Hexasomes in a Rod–Coil Amphiphilic Block Copolymer

The self‐assembly of a rod–coil amphiphilic block copolymer (ABCP) led to Im m and Pn m polymer cubosomes and p6mm polymer hexasomes. This is the first time that these structures are observed in a rod–coil system. By varying the hydrophobic chain length, the initial concentration of the polymer solution, or the solubility parameter of the mixed solvent, head–tail asymmetry is adjusted to control the formation of polymer cubosomes or hexasomes. The formation mechanism of the polymer cubosomes was also studied. This research opens up a new way for further study of the bicontinuous and inverse phases in different ABCP systems.     

Salting‐out assisted liquid–liquid extraction coupled to dispersive liquid–liquid microextraction for the determination of chlorophenols in wine by high‐performance liquid chromatography

A novel procedure of sample preparation combined with high‐performance liquid chromatography with diode array detection is introduced for the analysis of highly chlorinated phenols (trichlorophenols, tetrachlorophenols, and pentachlorophenol) in wine. The main features of the proposed method are (i) low‐toxicity diethyl carbonate as extraction solvent to selectively extract the analytes without matrix effect, (ii) the combination of salting‐out assisted liquid–liquid extraction and dispersive liquid–liquid microextraction to achieve an enrichment factor of 334–361, and (iii) the extract is analyzed by high‐performance liquid chromatography to avoid derivatization. Under the optimum conditions, correlation coefficients (r) were >0.997 for calibration curves in the range 1–80 ng/mL, detection limits and quantification limits ranged from 0.19 to 0.67 and 0.63 to 2.23 ng/mL, respectively, and relative standard deviation was <8%. The method was applied for the determination of chlorophenols in real wines, with recovery rates in the range 82–104%.     

Enhancement of Iodine–Hydride Interaction by Substitution and Cooperative Effects in NCX–NCI–HMY Complexes

The NCX‐NCI‐HMY (X=H, Cl, Br, I, Li; M=Be, Mg; Y=H, Li, Na) trimers are investigated to find ways to enhance the iodine–hydride interaction. The interaction energy in the NCI–HMH dimer is ?2.87 and ?5.87 kcal mol^?1 for M=Be and Mg, respectively. When the free H atom in the NCI–HMH dimer is replaced with an alkali atom, the interaction energy is enhanced greatly. When NCX is added into this dimer, the interaction energy of the iodine–hydride interaction is increased by 9–45 % and its increased percentage follows the order X=Cl<Br<H<I<Li and M=Be<Mg. The combination of the alkali substitution and the cooperativity results in a more prominent enhancing effect. The largest interaction energy is found for the NCLi–NCI–HMgLi trimer (?7.03 kcal mol^?1). The influence of the I???H interaction on the X???N interaction is also studied in the trimers. Both types of interactions are analyzed with NBO, AIM, and MEP. The interaction energy in the trimer is also unveiled by a many‐body analysis.     

Simple evaluation of Franck–Condon factors and non‐Condon effects in the Morse potential

The calculation of Franck–Condon factors between different 1‐D Morse potential eigenstates using a formula derived from the Wigner function is discussed. Our numerical calculations using a simple program written in Mathematica are compared with other calculations. We show that our results have a similar accuracy as those calculations performed with more sophisticated methods. We discuss the extension of our method to include non‐Condon effects in the calculation. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem 88: 280–295, 2002     

Smart Approach for In Situ One‐Step Encapsulation and Controlled Delivery of a Chemotherapeutic Drug using Metal–Organic Framework–Drug Composites in Aqueous Media

Controlled release of an anticancer drug, doxorubicin (dox), from metal–organic framework (MOF)–drug composites is demonstrated under different external stimuli. 1,3,5‐Benzenetricarboxylic acid (H₃BTC) is used as an organic ligand, and iron acetate and zinc nitrate are used as metal sources to synthesize Fe–BTC and Zn–BTC MOFs, which are known to be biocompatible. The in situ formation of MOF–drug composites demonstrates high drug loading capacity compared to conventional methods. The present methodology is devoid of any extra steps for loading the drug after synthesis. Moreover, the drug loading is also independent of pore size of the MOF as the drug molecules are embedded inside the MOF during their in situ formation. The drug release was monitored under external stimuli including change to acidic pH and the presence of biocompatible liposomes for a period of more than 72 h. Steady‐state fluorescence spectroscopy is used to monitor the drug release as a function of time and confocal laser scanning microscopy is used to unravel the post‐release fate of doxorubicin in the presence of liposomes. It is found that drug release rate is higher for the Zn–BTC–dox composite than for the Fe–BTC–dox composite. This is attributed to the stronger binding between dox and Fe‐BTC than that between dox and Zn–BTC. This study highlights a novel approach for the preparation of MOF–drug composites in an aqueous medium for future biomedical applications.     

First example of the correlated calculation of the one‐bond tellurium–carbon spin–spin coupling constants: Relativistic effects,vibrational corrections,and solvent effects

This work reports on the comprehensive calculation of the NMR one‐bond spin–spin coupling constants (SSCCs) involving carbon and tellurium, ¹J(¹²⁵Te,¹³C), in four representative compounds: Te(CH₃)₂, Te(CF₃)₂, Te(C?CH)₂, and tellurophene. A high‐level computational treatment of ¹J(¹²⁵Te,¹³C) included calculations at the SOPPA level taking into account relativistic effects evaluated at the 4‐component RPA and DFT levels of theory, vibrational corrections, and solvent effects. The consistency of different computational approaches including the level of theory of the geometry optimization of tellurium‐containing compounds, basis sets, and methods used for obtainig spin–spin coupling values have also been discussed in view of reproducing the experimental values of the tellurium–carbon SSCCs. Relativistic corrections were found to play a major role in the calculation of ¹J(¹²⁵Te,¹³C) reaching as much as almost 50% of the total value of ¹J(¹²⁵Te,¹³C) while relativistic geometrical effects are of minor importance. The vibrational and solvent corrections account for accordingly about 3–6% and 0–4% of the total value. It is shown that taking into account relativistic corrections, vibrational corrections and solvent effects at the DFT level essentially improves the agreement of the non‐relativistic theoretical SOPPA results with experiment. © 2016 Wiley Periodicals, Inc.     

Optimization of hydrophilic interaction LC by univariate and multivariate methods and its combination with salting‐out liquid–liquid extraction for the determination of antihypertensive drugs in the environmental waters

Hydrophilic interaction LC for the separation of four antihypertensive drugs was optimized by both univariate and multivariate methods. The column efficiency, resolution, and separation time were used as the three assessment parameters. The best separation condition of 97% ACN with 3% aqueous buffer containing 50 mM ammonium acetate at a pH of 3.0 was obtained by the two optimization methods. The multivariate optimization, orthogonal array design herein, was demonstrated to be a little tedious, but afforded a much better understanding of underlying separation factors. The content of ACN in the mobile phase contributed most significantly to separation. Furthermore, sample diluent and injection volume were found to influence the chromatographic performance. To match the hydrophilic interaction LC mobile phase, a proper sample pretreatment method, salting‐out liquid–liquid extraction, in which ACN was the extractant, was chosen. Since reserpine was unstable under both acidic and alkaline conditions, it was not studied in this part. The optimal salting‐out liquid–liquid extraction parameters were as follows: 400 μL ACN was added to 1 mL sample solution containing 500 mg NH₄Cl at a pH of 14.0. The linearity ranged from 0.01 to 1.00 μg/mL with r² > 0.9937. The LODs were between 1.9 and 2.5 ng/mL. The developed method was applied to the environmental water sample with good performance.     

Spin–orbit effects on magnetically induced current densities in the () clusters

This study reports the spin–orbit effects on the aromaticity of the , , , , , and anionic clusters via the magnetically induced current‐density method. All‐electron density functional theory (DFT) calculations were carried out using the four‐component Dirac‐Coulomb (DC) hamiltonian, including scalar and spin–orbit relativistic effects. The magnetic index of aromaticity was calculated by numerical integration over the current flow between two atoms in the pentagonal ring. These values were compared to the spin‐free values (spin–orbit coupling switched off), in order to assess the spin–orbit effect on aromaticity. It was found that in the heavy anions, and , there is a significant influence of the spin–orbit coupling. © 2018 Wiley Periodicals, Inc.     

Spatial,Hysteretic, and Adaptive Host–Guest Chemistry in a Metal–Organic Framework with Open Watson–Crick Sites

Biological and artificial molecules and assemblies capable of supramolecular recognition, especially those with nucleobase pairing, usually rely on autonomous or collective binding to function. Advanced site‐specific recognition takes advantage of cooperative spatial effects, as in local folding in protein–DNA binding. Herein, we report a new nucleobase‐tagged metal–organic framework (MOF), namely ZnBTCA (BTC=benzene‐1,3,5‐tricarboxyl, A=adenine), in which the exposed Watson–Crick faces of adenine residues are immobilized periodically on the interior crystalline surface. Systematic control experiments demonstrated the cooperation of the open Watson–Crick sites and spatial effects within the nanopores, and thermodynamic and kinetic studies revealed a hysteretic host–guest interaction attributed to mild chemisorption. We further exploited this behavior for adenine–thymine binding within the constrained pores, and a globally adaptive response of the MOF host was observed.     

Relativistic effects in the one‐bond spin–spin coupling constants involving selenium

One‐bond spin–spin coupling constants involving selenium of seven different types, ¹ J(Se,X), X = ¹H, ¹³C, ¹⁵ N, ¹⁹ F, ²⁹Si, ³¹P, and ⁷⁷Se, were calculated in the series of 14 representative compounds at the SOPPA(CCSD) level taking into account relativistic corrections evaluated both at the RPA and DFT levels of theory in comparison with experiment. Relativistic corrections were found to play a major role in the calculation of ¹ J(Se,X) reaching as much as almost 170% of the total value of ¹ J(Se,Se) and up to 60–70% for the rest of ¹ J(Se,X). Scalar relativistic effects (Darwin and mass‐velocity corrections) by far dominate over spin–orbit coupling in the total relativistic effects for all ¹ J(Se,X). Taking into account relativistic corrections at both random phase approximation and density functional theory levels essentially improves the agreement of theoretical results with experiment. The most ‘relativistic’ ¹ J(Se,Se) demonstrates a marked Karplus‐type dihedral angle dependence with respect to the mutual orientation of the selenium lone pairs providing a powerful tool for stereochemical analysis of selenoorganic compounds. Copyright © 2014 John Wiley & Sons, Ltd.     

Characterization and screening of metals,metalloids and biomarkers in crude oil by ICP–MS/OES,and GC–MS techniques after digestion by microwave‐induced combustion

A method for digestion of light and medium Iraqi crude oils (Basrah and Khanaken oils) using microwave‐induced combustion (MIC) in closed vessels is described for the determination of Hg, Au, Cu, Al, Ca, Co, K, Mg, Si and Sr by inductively coupled plasma optical emission spectrometry (ICP–OES) and Mo, Ti, Mn, Li, Se^?1, Rb, Ag, Ba, Pb, As, Cd, Cr, Fe, Ni, V and Zn by inductively coupled plasma mass spectrometry (ICP–MS). Upon using MIC it was possible to obtain lower limits of detection by ICP–MS and also by ICP–OES compared with those obtained by microwave‐assisted digestion. The MIC was the best choice with regard to the possibility of using dilute nitric acid as an absorbing solution, which is important to minimize the interference encountered by ICP–MS and ICP–OES.The physicochemical parameters and some contaminants of crude oil samples were analyzed to classify and assess the quality of the crude oils. This study determines the viability of the use of Fourier transform infrared spectroscopy as an alternativee to traditional petroleum geochemical methods for crude oil characterization. The infrared fingerprints agree with the results obtained from GC–MS analysis.     

Two Robust Porous Metal–Organic Frameworks Sustained by Distinct Catenation: Selective Gas Sorption and Single‐Crystal‐to‐Single‐Crystal Guest Exchange

Assembly of copper(I) halide with a new tripodal ligand, benzene‐1,3,5‐triyl triisonicotinate (BTTP4), afforded two porous metal–organic frameworks, [Cu₂I₂(BTTP4)]?2 CH₃CN ( 1? 2 CH₃CN) and [CuBr(BTTP4)]?(CH₃CN ? CHCl₃ ? H₂O) ( 2? solvents), which have been characterized by IR spectroscopy, thermogravimetry (TG), single‐crystal, and powder X‐ray diffraction (PXRD) methods. Compound 1.CH3CN is a polycatenated 3D framework that consists of 2D (6,3) networks through inclined catenation, whereas 2 is a doubly interpenetrated 3D framework possessing the ThSi₂‐type ( ths ) (10,3)‐b topology. Both frameworks contain 1D channels of effective sizes 9×12 and 10×10 Ų, which amounts to 43 and 40 % space volume accessible for solvent molecules, respectively. The TG and variable‐temperature PXRD studies indicated that the frameworks can be completely evacuated while retaining the permanent porosity, which was further verified by measurement of the desolvated complex [Cu₂I₂(BTTP4)] ( 1′ ). The subsequent guest‐exchange study on the solvent‐free framework revealed that various solvent molecules can be adsorbed through a single‐crystal‐to‐single‐crystal manner, thus giving rise to the guest‐captured structures [Cu₂I₂(BTTP4)]?C₆H₆ ( 1.benzene ), [Cu₂I₂(BTTP4)]?2 C₇H₈ ( 1.2toluene ), and [Cu₂I₂(BTTP4)]?2 C₈H₁₀ ( 1.2ethyl benzene ). The gas‐adsorption investigation disclosed that two kinds of frameworks exhibited comparable CO₂ storage capacity (86–111 mL g^?1 at 1 atm) but nearly none for N₂ and H₂, thereby implying its separation ability of CO₂ over N₂ and H₂. The vapor‐adsorption study revealed the preferential inclusion of aromatic guests over nonaromatic solvents by the empty framework, which is indicative of selectivity toward benzene over cyclohexane.     

Synthesis and crystal structure of a new Cu3Au‐type ternary phase in the Au–In–Pd system: distribution of atoms over crystallographic positions

A new Cu₃Au‐type ternary phase (τ phase) is found in the AuPd‐rich part of the Au–In–Pd system. It has a broad homogeneity range based on extensive (Pd,Au) and (In,Au) replacement, with the composition varying between Au_17.7In_25.3Pd_57.0 and Au_50.8In_16.2Pd_33.0. The occupancies of the crystallographic positions were studied by single‐crystal X‐ray diffraction for three samples of different composition. The sites with mm symmetry are occupied by atoms with a smaller scattering power than the atoms located on 4/mmm sites. Two extreme structure models were refined. Within the first, the occupation type changes from (Au,In,Pd)₃(Pd,In) to (Au,Pd)₃(In,Pd,Au) with an increase in the Au gross content. For the second model, the occupation type (Au,In,Pd)₃(Pd,Au) remains essentially unchanged for all Au concentrations. Although the diffraction data do not allow the choice of one of these models, the latter model, where Au substitutes In on 4/mmm sites, seems to be preferable, since it agrees with the fact that the homogeneity range of the τ phase is inclined to the Au corner and provides the same occupation type for all the studied samples of different compositions.     

Synthesis of polymer particles possessing radical initiating sites on the surface by emulsion copolymerization and construction of core–shell structures by a photoinduced atom transfer radical polymerization approach

The crosslinked polystyrene particles possessing photofunctional N,N‐diethyldithiocarbamate groups on their surface were prepared by free‐radical emulsion copolymerization of a mixture of styrene, divinylbenzene and 4‐vinylbenzyl N,N‐diethyldithiocarbamate with redox system as an initiator under UV irradiation. In this copolymerization, the inimer 4‐vinylbenzyl N,N‐diethyldithiocarbamate acted the formation of hyperbranched structures by living radical photopolymerization. The particle sizes (number‐average particle diameter = 214–523 nm) were controlled by varying the feed amount of surfactant and size distributions were relatively narrow. Subsequently, core–shell particles were synthesized by photoinduced atom transfer radical polymerization approach of methyl methacrylate initiated by photofunctional polystyrene particles as a macroinitiator. Such core–shell particles were stabilized sterically by grafted chains in organic solvents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1771–1777, 2007     

In Situ Observation of Successive Crystallizations and Metastable Intermediates in the Formation of Metal–Organic Frameworks

Understanding the driving forces controlling crystallization is essential for the efficient synthesis and design of new materials, particularly metal–organic frameworks (MOFs), where mild solvothermal synthesis often allows access to various phases from the same reagents. Using high‐energy in situ synchrotron X‐ray powder diffraction, we monitor the crystallization of lithium tartrate MOFs, observing the successive crystallization and dissolution of three competing phases in one reaction. By determining rate constants and activation energies, we fully quantify the reaction energy landscape, gaining important predictive power for the choice of reaction conditions. Different reaction rates are explained by the structural relationships between the products and the reactants; larger changes in conformation result in higher activation energies. The methods we demonstrate can easily be applied to other materials, opening the door to a greater understanding of crystallization in general.     

Activation of – N=CH – bond in a Schiff base by divalent nickel monitored by NMR evidence

The Schiff base, 2–salicylidene–4–aminophenyl benzimidazole in ethanol undergoes activation of –N=CH– bond by Ni²⁺ in the presence of ammonia or primary alkyl amine to produce nickel complexes of the formula Ni{o–C₆H₄(O)CH NR}₂ . n H₂O [R = H, Me; n = 0; R = Et, n = 0.5] and 4–aminophenyl benzimidazole. The products have been identified by elemental analysis, magnetic susceptibility measurements and IR, ESR, mass and extensive NMR spectral studies. The possible mechanism for the activation of –N=CH – bond has also been proposed. Copyright © 2012 John Wiley & Sons, Ltd.     

Periodic minimal surface structures in bicontinuous lipid–water phases and nanoparticles

The accumulated evidence for the existence of periodic minimal surface (PMS) bilayer structure of the bicontinuous cubic phases in lipid–water systems is summarized. There are three fundamental PMS: the G, D, and P types. These three and no others have been observed in lipid–water systems. Due to the so-called Bonnet relation, the PMS structures are isometric conjugates to one another at coexistence, which determines the cubic axis ratio and water content at equilibrium. A number of lipid systems exhibiting coexisting cubic phases have been examined in relation to fulfilling the Bonnet relation. In all cases with known unit cell dimensions, the phases are Bonnet-related. This is regarded as strong evidence for their PMS structure. The phase transitions in relation to swelling and water content also fulfill the Bonnet relations. Aside from bulk phases with PMS structure, it has also been shown possible to produce nanoparticles with internal PMS structure. New developments enable the manufacturing of such particles with uniform size and internal structure, of interest in practical applications such as in vivo delivery of drugs.     

Studies of proteasome inhibition and apoptosis induction in triple‐negative breast cancer cells by novel amino acid–polypyridine–copper complex

An innovative ternary copper(II) complex, [Cu(Cl‐PIP)(Tyr)Cl]_n, has been synthesized and characterized using infrared spectroscopy, elemental analysis and single‐crystal X‐ray diffraction analysis. X‐ray crystallography indicates that the Cu atom is five‐coordinated in a square‐pyramidal configuration. The unit forms a one‐dimensional chain along the crystallographic c‐axis. The complex was screened for cytotoxicity against a panel of eight human cancer cell lines, namely MDA‐MB‐231, CAL‐51, K562, HeLa, SGC‐7901, A549, MCF‐7 and SMMC‐7721. The best anticancer activity was obtained with triple‐negative breast cancer CAL‐51 and MDA‐MB‐231 cell lines, with IC₅₀ values in the range 0.035–0.10 μM, and this was better than using carboplatin. The complex inhibits proteasomal chymotrypsin‐like activity, and docking studies reveal its interaction with 20S proteasome. In addition, the complex causes accumulation of ubiquitinated proteins, induces apoptosis and inhibits cell proliferation, indicating its great potential as a novel therapy for triple‐negative breast cancer.