IR-Spectroscopic Study of Complex Formation of Nitrogen Oxides (NO, N2O) with Cationic Forms of Zeolites and the Reactivity of Adsorbed Species in CO and CH4 Oxidation

The formation of complexes and disproportionation of nitrogen oxides (NO, N2O) on cationic forms of LTA, FAU, and MOR zeolites was investigated by diffuse-reflectance IR spectroscopy. N2O is adsorbed on the samples under study in the molecular form and the frequencies of the first overtone of the stretching vibrations ν10–2 and the combination bands of the stretching vibrations with other vibrational modes for N2O complexes with cationic sites in zeolites (ν30–1 + ν10–1, ν10–1 + δ0–2) are more significantly influenced by the nature of the zeolite. The presence of several IR bands in the region of 2400–2600 cm−1 (the ν10–1 + δ0–2 transitions) for different zeolite types was explained by the availability of different localization sites for cations in these zeolites. The frequencies in this region also depend on the nature of the cation (its charge and radius). The data can be explained by the specific geometry of the N2O complex formed, presumably two-point adsorption of N2O on a cation and a neighboring oxygen atom of the framework. Adsorption of CO or CH4 on the samples with preliminarily adsorbed N2O at 20–180 °C does not result in any oxidation of these molecules. NO+ and N2O3 species formed by disproportionation of NO are capable of oxidizing CO and CH4 molecules to CO2, whereas NOx is reduced simultaneously to N2 or N2O. The peculiarities in the behavior of cationic forms of different zeolites with respect to adsorbed nitrogen oxides determined by different density and localization of cations have been established.

EGFR transactivates RON to drive oncogenic crosstalk

Crosstalk between different receptor tyrosine kinases (RTKs) is thought to drive oncogenic signaling and allow therapeutic escape. EGFR and RON are two such RTKs from different subfamilies, which engage in crosstalk through unknown mechanisms. We combined high-resolution imaging with biochemical and mutational studies to ask how EGFR and RON communicate. EGF stimulation promotes EGFR-dependent phosphorylation of RON, but ligand stimulation of RON does not trigger EGFR phosphorylation – arguing that crosstalk is unidirectional. Nanoscale imaging reveals association of EGFR and RON in common plasma membrane microdomains. Two-color single particle tracking captured formation of complexes between RON and EGF-bound EGFR. Our results further show that RON is a substrate for EGFR kinase, and that transactivation of RON requires formation of a signaling competent EGFR dimer. These results support a role for direct EGFR/RON interactions in propagating crosstalk, such that EGF-stimulated EGFR phosphorylates RON to activate RON-directed signaling.

Photoinduced Atom Transfer Radical Addition/Cyclization Reaction between Alkynes or Alkenes with Unsaturated α-Halogenated Carbonyls

We have developed a photochemical ATRA/ATRC reaction that is mediated by halogen bonding interactions. This reaction is caused by the reaction of malonic acid ester derivatives containing bromine or iodine with unsaturated compounds such as alkenes and alkynes in the presence of diisopropylethylamine under visible light irradiation. As a result of various control experiments, it was found that the formation of complexes between amines and halogens by halogen-bonding interaction occurs in the reaction system, followed by the cleavage of the carbon–halogen bonds by visible light, resulting in the formation of carbon radicals. In this reaction, a variety of substrates can be used, and the products, cyclopentenes and cyclopentanes, were obtained by intermolecular addition and intramolecular cyclization.

Nonlinear regression for analysis of the uptake of KMnO4 from aqueous solutions onto natural marl

The present work aims to evaluate the performance of raw marl collected from the region of Oum El Bouaghi on the elimination of KMnO4 from aqueous solution. The adsorption capacities were studied using the batch technique as a function of pH, initial concentration and temperature. The maximum adsorption for KMnO4 was found to be 83.517% at pH 3.0. When the pH is low (pH<3.0), the uptake of KMnO4 occurs with an electrostatic attraction between the MnO4-ions and the surface proton groups, while at pH ≥3.0-8.0, the formation of complexes with the surface functional groups during the adsorption process and/or cation exchange are responsible for retention of Mn(II) ions onto marl. Experimental adsorption data were modeled with different nonlinear isotherms and kinetic models. Furthermore, statistical errors (SSE, SD, ARE, χ 2, R2 and R2 adj) were calculated to choose the suitable model. Langmuir isotherm was found to be best for fitting the experimental data. The calculated thermodynamic parameters indicated that adsorption process was physical, spontaneous and endothermic in nature. From this work, it was concluded that the natural marl can be used for effective elimination of KMnO4 from aqueous solution and wastewater.

USING OPTICALLY ACTIVE CHIRAL CROWN ETHER AT ENANTIOMERIC SEPARATION OF AMINES

The synthesized S-enantiomer of the crown ether was used as an adsorbent to separate the racemic mixture of L-alanine ether of phenamine into individual diastereomers by column chromatography. Chromatographic separation occurred due to the formation of complexes of different stability between diastereomers and optically selective adsorbents on a host-guest principle. The separated diastereomers were converted into enantiomers by hydrolysis. The structure and optical activity of the synthesized crown ether and separated enantiomers were investigated by physicochemical methods

Formation of complexes consisting of impurity Mn atoms and group VI elements in the crystal lattice of silicon

Formation of complexes of impurity Mn atoms with impurity atoms of group VI elements (S, Se, Te) in the silicon crystal lattice has been studied. It has been experimentally found that formation of electrically neutral molecules with an ionic-covalent bond between Mn atoms and group VI elements takes place, which possibly leads to formation of new Si2BVI++Mn binary unit cells in the silicon crystal lattice. It has been shown that in the samples Si<S, Mn>, Si<Se, Mn> and Si<Te, Mn>, an intense complex formation occurs at the temperatures 1100, 820 and 650°C, respectively.

Monochelic Versus Telechelic Poly(Methyl Methacrylate) as a Matrix for Photoluminescent Nanocomposites with Quantum Dots

Nanocomposites based on CdSe or CdSe/ZnS quantum dots (QDs) and poly(methyl methacrylate) (PMMA) of different molecular weights and functionality were synthesized by ligand exchange of oleic acid with RAFT-based PMMA. The successful ligand exchange was confirmed by dynamic light scattering in combination with the approach “macromolecules—ghosts” and transmission electron microscopy. Comparative study of mono- and telechelics of PMMA revealed the similarities and differences in their behavior in formation of complexes with QDs and the optical properties of the corresponding nanocomposites. Telechelics exhibited higher efficiency in the complex formation and seemed to be promising candidates for the construction of devices based on QDs and polymer matrix for optical applications.

Binding Between Cyclohexanohemicucurbit[n]urils and Polar Organic Guests

Inherently chiral, barrel-shaped, macrocyclic hosts such as cyclohexanohemicucurbit[n]urils (cycHC[n]) bind zinc porphyrins and trifluoroacetic acid externally in halogenated solvents. In the current study, we tested a set of eighteen organic guests with various functional groups and polarity, namely, thiophenols, phenols, and carboxylic and sulfonic acids, to identify a preference toward hydrogen bond–donating molecules for homologous cycHC[6] and cycHC[8]. Guests were characterized by Hirshfeld partial charges on acidic hydrogens and their binding by 1H and 19F NMR titrations. Evaluation of association constants revealed the complexity of the system and indirectly proved an external binding with stoichiometry over 2:1 for both homologs. It was found that overall binding strength is influenced by the stoichiometry of the formed complexes, the partial atomic charge on the hydrogen atom of the hydrogen bond donor, and the bulkiness of the guest. Additionally, a study on the formation of complexes with halogen anions (Cl− and Br−) in methanol and chloroform, analyzed by 1H NMR, did not confirm complexation. The current study widens the scope of potential applications for host molecules by demonstrating the formation of hydrogen-bonded complexes with multisite hydrogen bond acceptors such as cycHC[6] and cycHC[8].

Synthetic, structural and biochemical approach of the macro cyclic complexes of manganese (II) and tin (II)

This study presents a brief account of the synthesis, spectroscopic and biochemical aspects of tetraazamacrocyclic complexes of managenese (II) and tin (II). The complexes of manganese (II) and tin (II) were prepared by the template condensation of metal salts with phthalic acid and diamines (1,3-diaminobutane and 1,4- diaminobutane) in 1:2:2 molar ratio. All the complexes are soluble in polar solvent. The structures were investigated using elemental analyses, molecular weight determinations, conductivity measurements, electronic, infrared and X-Ray diffraction spectral studies. The elemental analyses are consistent with the formation of complexes of the type [M(Macn)Cl2] (where, n=1-2, M=Mn(II), Sn (II)). An octahedral geometry around the metal ion is suggested for these complexes. All the complexes were screened against several fungi and bacteria to assess its biological properties and results are discussed.The importance of this method includes shorter reaction time and high yield.

The Potential Role of Polyelectrolyte Complex Nanoparticles Based on Cashew Gum, Tripolyphosphate and Chitosan for the Loading of Insulin

Polyelectrolytic complexation has stood out due to its application in the development of drug delivery systems using biopolymers as raw materials. The formation of complexes between cashew gum and chitosan can be intermediated by cross-links, mediated by the action of the sodium tripolyphosphate crosslinking agent. These polymers have been used in the nanotechnological development of formulations to protect peptide drugs, such as insulin, allowing their oral administration. In this work, we describe the development of polyelectrolytic complexes from cashew gum and chitosan as biopolymers for oral administration of insulin. The obtained complexes showed a mean particle size of 234 nm and polydispersity index of 0.2. The complexes were 234 nm in size, PDI 0.2, zeta potential −4.5 mV and 22% trapping. The obtained complexes demonstrated considerable and promising characteristics for use as oral insulin delivery systems.