CH CH2 Research Articles

High-level expression of human CH2 domain from the Fc region in Pichia pastoris and preparation of anti-CH2 antibodies.

Pichia pastoris is a popular eukaryotic system employed for the fast, simple and inexpensive production of recombinant protein including biotherapeutics such as human albumin. The CH2 domain of human Immunoglobulin G (IgG) is a promising scaffold for developing novel therapeutics. To accelerate the research of CH2 domain, we have established a procedure to highly express human CH2 domain (∼150 mg/l) as well as human Fc (∼30 mg/l) in yeast P. pastoris. The procedure yields, simultaneously, a major glycosylated (∼70%) and non-glycosylated (∼30%) fractions. They can be easily separated with high purity. Although both forms of CH2 domain have essentially the same secondary structure, the presence of the glycan increased the thermal stability of the CH2 domain by about 5°C as determined from calorimetry. The purified glycosylated CH2 domain elicited polyclonal antibodies in mouse, recognizing not only the CH2 domain, but also recombinant human Fc and the commercial IgG1 antibody Rituxan. Protein A and Protein G binding to the kink region between CH2 domain and CH3 domain of human Fc are used to purify therapeutic proteins. Therefore, these antibodies are candidates to develop a novel affinity material to purify human antibodies using their CH2 domain.

Significant inhibition of garlic essential oil on benzo[a]pyrene formation in charcoal-grilled pork sausages relates to sulfide compounds

To addgarlic more conveniently, the substitute–garlic essential oil(GEO)is wildly applied in meat product for flavor improvement. However, the effects of GEOon chemical hazard formation, such as benzo[a]pyrene (BaP), in meat processing have not been studied. This study focused on the inhibitory effect of garlic (0.05–0.15%, w/w), GEO (0.002–0.006%, w/w) and the active sulfide compounds (0.006%, w/w) on the formation of BaP in charcoal-grilled pork sausages. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity of the garlic, GEO and sulfide compounds was also determined. The results showed that the garlic was efficient in the decrease of DPPH free radicals (14.91–23.39%) and BaP content (37.2–62.3%). GEO was also efficient in scavenging DPPH free radicals (14.17–26.20%) and reducing BaP formation (29.1–57.1%). Gas chromatography-mass spectrometer (GC–MS) analysis identified a total of 41 compounds, of which six major sulfide compounds (allyl methyl sulfide, diallyl sulfide, allyl methyl disulfide, diallyl disulfide, allyl methyl trisulfide and diallyl trisulfide) were screened to assess their inhibition of BaP generation. The BaP inhibition of these sulfide compounds were dependent on the number of sulfur (-S-) and thioallyl group (–S–CH2–CH═CH2); and allyl methyl trisulfide (AMTS) showed the highest BaP inhibition (63.3%). A significant correlation was found between their BaP inhibition and DPPH scavenging activity (Spearman correlation = 0.91, P < 0.001), which indicates that the mechanism of sulfides influencing BaP formation in grilling sausage is related to free radical reaction. Our research gives an insight into the theoretical basis about application of GEO to inhibit BaP during food processing and supports use of GEO as a natural additive in meat products.

Comparative Studies on Flotation Performance of Saturated Fatty Acids and Unsaturated Fatty Acids Separated from Hogwash Oil

Low flotation recovery, high pulp temperature, and large dosage of reagents are the typical disadvantages when using mixed fatty acids (MFA) prepared from hogwash oil for flotation directly. To determine the type of fatty acid that yields poor flotation performance, flotation performance and adsorption characteristics of saturated fatty acids (SFA) and unsaturated fatty acids (UFA) separated from the MFA were studied in our work. GC-MS, FT-IR, iodine value detection and melting point measurement showed that UFA contained –(CH=CH–CH2)n- groups and had much lower melting point. Quartz flotation tests were used to compare the flotation performance of UFA and SFA, which showed that UFA had excellent low-temperature floatability, and the flotation recovery of UFA was 35 percentage points higher than that of SFA at 20 °C and pH = 11.5. Zeta potential, FT-IR and XPS analysis indicated that UFA and SFA could adsorb onto the surface of activated quartz through chemisorption and hydrogen bonding. However, the adsorption of UFA was much stronger and more favorable; thus, the reason MFA have poor flotation performance was the presence of SFA.

Theoretical study of pentavalent halosiliconates: structure and charge delocalization

This study is performed to detect the pentavalent silicon center in the structure of pentavalent halosiliconate R—O—Si(CH3)3X– and halotrimethylsilyloxyfurane structures (X—TMSOF), (X = F–; Cl–; Br–) and (R = CH3—; CH2—CH3; —CH(CH3)2; —CH=CH2; C6H5—). DFT calculations at the B3LYP/6-31G(d) level are caried out to understand their structures and charge delocalization. These intermediates are obtained by attacking the silicon center in trimethyl-alkoxysilanes and trimethyl-silyloxyfurane with halogen ions X–. The results obtained show that the attack by F– generates more stable structures because of the Si—F bond strong. In the case of Br– and Cl–, the structure of intermediates appears as an interaction between the ions and the silicon center. NBO analysis shows that one of F– lone pairs takes part in the Si—F bond formation. However, the lone pairs of Br– and Cl– do not contribute to generate a real bonding.

The "Hidden" Reductive [2+2+1]-Cycloaddition Chemistry of 2-Phosphaethynolate Revealed by Reduction of a Th-OCP Linkage.

The reduction chemistry of the newly emerging 2‐phosphaethynolate (OCP)− is not well explored, and many unanswered questions remain about this ligand in this context. We report that reduction of [Th(TrenTIPS)(OCP)] (2, TrenTIPS=[N(CH2CH2NSiPri 3)]3−), with RbC8 via [2+2+1] cycloaddition, produces an unprecedented hexathorium complex [{Th(TrenTIPS)}6(μ‐OC2P3)2(μ‐OC2P3H)2Rb4] (5) featuring four five‐membered [C2P3] phosphorus heterocycles, which can be converted to a rare oxo complex [{Th(TrenTIPS)(μ‐ORb)}2] (6) and the known cyclometallated complex [Th{N(CH2CH2NSiPri 3)2(CH2CH2SiPri 2CHMeCH2)}] (4) by thermolysis; thereby, providing an unprecedented example of reductive cycloaddition reactivity in the chemistry of 2‐phosphaethynolate. This has permitted us to isolate intermediates that might normally remain unseen. We have debunked an erroneous assumption of a concerted fragmentation process for (OCP)−, rather than cycloaddition products that then decompose with [Th(TrenTIPS)O]− essentially acting as a protecting then leaving group. In contrast, when KC8 or CsC8 were used the phosphinidiide C−H bond activation product [{Th(TrenTIPS)}Th{N(CH2CH2NSiPri 3)2[CH2CH2SiPri 2CH(Me)CH2C(O)μ‐P]}] (3) and the oxo complex [{Th(TrenTIPS)(μ‐OCs)}2] (7) were isolated.

Catalytic mechanism and selectivity prediction for syngas conversion over pure and K-promoted Mo2C catalysts

Density functional theory (DFT) calculations were performed to reveal the intricate pathways of syngas conversion over Mo2C catalysts. Our computational results show that CO activation occurs preferably via its hydrogenation to HCO on the Mo2C (001) surface. The Mo-Mo bridge site is found to be the active site, and ethanol formation involves the HCO*, H2CO, CH2, CH3, CH3CHO, and CH3CH2O intermediates. Product selectivity in this reaction is mainly affected by reaction steps involving CH2, and ethanol yield is limited by the high energy barriers of CH3+CHO coupling and C2H5O hydrogenation. Since K has been experimentally shown to be an outstanding promoter for increasing alcohol selectivity, we further investigated the effect of the K promoter to the catalytic performance of the Mo2C catalyst. Compared to the pure Mo2C (001) surface, K-Mo2C (001) promotes the activity of the CH3+CHO coupling. To give a semi-quantitative estimate for the product selectivity, we used the effective energy barrier difference (ΔEeff) between CH2+CH2 coupling and CH3+CHO coupling as an energy descriptor. The ΔEeff value of the K-Mo2C (001) surface is significantly greater than that of the pristine surface, indicating higher selectivity of ethanol over the K-promoted surface, which is consistent with the experimental observation. Furthermore, comparing the Mo2C(001) and (100) surfaces, we find that the Mo2C (001) surface exhibits better activity toward CO activation, whereas the Mo2C (100) surface favors the CC coupling reaction.

Monitoring the oxidation state evolution of unsaturated fatty acids in four microwave-treated edible oils by low-field nuclear magnetic resonance and 1H nuclear magnetic resonance

Edible oils oxidize during microwave heating, which may affect their nutritional value and safety. Exploring the oxidation mechanisms of unsaturated fatty acids in edible oils to determine which are suitable for microwave heating is therefore important. We used GC-MS, low-field NMR, and 1H NMR techniques to study functional-group oxidation, the unsaturated fatty acid change law, and the distribution and migration of protons in various functional groups of four common vegetable cooking oils during microwave treatment. We show that the acid values of sunflower, soybean, peanut, and corn oil increased by 14%, 31%, 36%, and 101%, respectively, while the concentrations of malondialdehyde increased by 115%, 664%, 158%, and 333%, respectively, and the peroxide value fluctuated with increasing microwave power. The C16:0 concentrations of all four edible oils increased by more than 50%, and the concentration of polyunsaturated fatty acids decreased by more than 30% during microwave treatment; hence sunflower oil is the most suitable of the above-mentioned oils for daily microwave heating. In addition, we recommend the use of three characteristic functional groups to monitor the oxidative changes undergone by oils: olefinic H (CH = CH), diallyl CH2 (CH = CH–CH2–CH = CH), and allyl CH2 (CH = CH–CH2).

Effect of leucine on the activation energy of the corrosion process of St3 steel in 0,04% CH3COOH solution – kerosene system

In this investigation we studied the temperature dependence of the protection effect of St3 steel against corrosion in 0,04% CH3COOH solution-kerosene system by gravimetric method of leucine (derivative of aliphatic monoamino monocarboxylic acids – AL-MAMCA: with the general formula CH3-CH(CH3)-CH2-CH(NH2)-COOH). Previously at 20 ºC we investigated this corrosion process in various two-phase acid and neutral electrolyte solutions in hydrocarbon systems and revealed a good protection effect of leucine. On the basis of the obtained data, the activation energy in the corrosion process of St3 steel has been calculated without and in the presence of the leucine in the aggressive system shown by analytical and graphical methods (graph of dependence of lgK on 1/T). It was found that the addition of leucine to the aggressive system in terms of corrosion causes a significant increase in the activation energy of St3 steel in the corrosion process, and thus complicates the process of this undesirable process. It has been shown that in parallel with the increase in the temperature of the aggressive environment in terms of corrosion, the previously physically adsorbed leucine molecules on the surface of St3 steel are gradually replaced by chemically adsorbed ones, thus further strengthening the metal – inhibitor bond.

Intrinsic Magnetic Order of Chemically Exfoliated 2D Ruddlesden-Popper Organic-Inorganic Halide Perovskite Ultrathin Films.

Thin film fabrication of 2D layered organic-inorganic hybrid perovskites (2D-OIHPs) for spintronic applications has been attempted using solution-based process like Langmuir-Blodgett technique. However, monolayer or few-layered 2D magnets are not yet realized, even though a wide spectrum of 2D Ruddlesden-Popper (RP) OIHPs are known as quasi-2D Heisenberg magnets in bulk compounds. Here, chemical exfoliation by solvent engineering is applied to successfully synthesize large-sized, few unit-cell-thick 2D RP-OIHPs. Comprehensive structural characterization reveals that binary co-solvents with high relative polarity in spin coating technique are the most effective among nine kinds of solvents. Above all, this enables few-layered 2D RP-OIHP ultrathin films sustaining their intrinsic magnetic order. It is found that XY-like magnetic anisotropy driven by Jahn-Teller effect responsible for ferromagnetism in seven-layered (C6 H5 CH2 CH2 NH3 )2 CuCl4 ultrathin films remains very robust, whereas Ising-like dipolar anisotropy responsible for canted antiferromagnetism in ten-layered (C6 H5 CH2 CH2 NH3 )2 MnCl4 ultrathin films is greatly reduced. It is expected that ferromagnetism even at monolayer limit should be possible by means of further sophisticated solvent engineering as long as Jahn-Teller effect is active. The chemical exfoliation using solvent engineering unambiguously can bring about a new breakthrough in the development of 2D RP-OIHP van der Waals magnets for ultrahigh energy-efficient spintronic, opto-spintronic devices.

Acid‐Base Interactions of Pyrazine, Ethyl Acetate, Di‐alcohols, and Lysine with the cyclic Alumosiloxane (Ph2SiO)8[Al(O)OH]4 in View of Mimicking Al2O3(H2O) Surface Reactions

The etherate of (Ph2SiO)8[Al(O)OH]4 can be transformed into the pyrazine adduct (Ph2SiO)8[Al(O)OH]4·3N(C2H2)2N (1), the ethyl acetate adduct (Ph2SiO)8[Al(O)OH]4·3H3C‐C(O)OC2H5 (2), the 1,6‐hexane diol adduct (Ph2SiO)8[Al(O)OH]4·2HO–CH2(CH2)4CH2–OH (3) and the 1,4‐cyclohexane diol adduct (Ph2SiO)8[Al(O)OH]4·4HO–CH(CH2CH2)2CH–OH (4). In all compounds the OH groups of the starting material bind to the bases through O–H···N (1) or O–H···O hydrogen bonds (2, 3, 4) as found from single‐crystal X‐ray diffraction analyses. Whereas in 1 only three of the central OH groups bind to the pyrazines, in 2 two of them bind to the same carbonyl oxygen atom of the ethyl acetate resulting in an unprecedented O–H···O···H–O double hydrogen bridge. The hexane diol adduct 3 in the crystal forms a one‐dimensional coordination polymer with an intramolecularly to two OH groups grafted hexane diol loop, while the second hexane diol is connecting intermolecularly. In the cyclohexane diol adduct 4 all OH groups of the central Al4(OH)4 ring bind to different diols, leaving one alcohol group per diol uncoordinated. These “free” OH groups form an (O‐H···)4 assembly creating a three‐dimensional overall structure. When reacting with (Ph2SiO)8[Al(O)OH]4 lysine loses water, turns into the cyclic 3‐amino‐2‐azepanone, and transforms through chelation of one of the aluminum atoms the starting material into a new polycycle. The isolated compound has the composition (Ph2SiO)12[Al(O)OH]4[Al2O3]2·4 C6H12N2O·6(CH2)4O (5).

Modulation of Nuclearity in CuII -MnII Complexes of a N2 O2 Donor Ligand Depending upon Carboxylate Anions: Structures, Magnetic Properties and Catalytic Oxidase Activities.

Three new hetero-metallic copper(II)-manganese(II) complexes, [(CuL)2 Mn3 (C6 H5 CO2 )6 ] (1), [(CuL)2 Mn(CH3 CO2 )2 ] (2), and {[(CuL)2 Mn(C6 H5 CH2 CO2 )2 ] ⋅ 2CH3 CN} (3), have been synthesized using [CuL] as ''metalloligand'' (where H2 L=N,N'-bis(2-hydroxynaphthyl-methylidene)-1,3-propanediamine). Single-crystal structural analyses show an almost linear penta-nuclear structure for complex 1 where a square planar [CuL] unit is connected to each of the two terminal MnII ions of a linear, centrosymmetric [Mn3 (benzoate)6 ] unit through the double phenoxido bridges. Both complexes 2 and 3 possess a linear tri-nuclear structure where two terminal square-pyramidal [CuL] units are bonded to the central MnII ion through double phenoxido oxygen atoms along with a syn-syn bridging acetate (for 2)/phenyl acetate (for 3). All three complexes exhibit catecholase, and phenoxazinone synthase-like activities under aerial conditions. For catecholase like activity, the turnover numbers (kcat ) are 595, 40, and 205 h-1 whereas, for phenoxazinone synthase like activity, the turnover numbers are 25, 4, and 11 h-1 for complexes 1-3, respectively. The mechanism of both catalytic oxidase activities is proposed on the basis of mass spectral evidences. Variable-temperature (2-300 K) dc molar magnetic susceptibility measurements of 1 reveal antiferromagnetic interactions between the Cu-Mn centres (J1 =-29.3 cm-1 ), and also between the Mn-Mn centres of the [Mn3 (benzoate)6 ] unit (J2 =-0.68 cm-1 ). On increasing the magnetic field at 2 K, its ground spin state changes from S=3/2 to S=5/2 at 4 T, attributable to the low value of J2 which makes the excited spin states close in energy with the ground spin state. Complexes 2 and 3 show antiferromagnetic coupling interactions between the Cu-Mn pairs with J values of -9.51, and -5.32 cm-1 , respectively.

Evaluation by IR spectroscopy of the degradation of different types of commercial polyethylene exposed to UV radiation and domestic compost in ambient conditions

AbstractDifferent types of commercial polyethylene films, low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), and biodegradable polyethylene (BIO‐PE), were exposed to UV‐B radiation at different exposure time and domestic composting during spring and fall at ambient conditions. The effects of UV‐B radiation and domestic composting on LDPE, HDPE, and BIO‐PE degradation were characterized by FTIR spectroscopy. LDPE, HDPE, and BIO‐PE exposed to UV‐B radiation underwent photo oxidation reactions leading to the formation of carbonyl (CO) and vinyl (CH2CH) groups and hydrophilic surface modification. Also, the exposure of LDPE, HDPE, and BIO‐PE to domestic composting at ambient conditions at different seasons suffered biodegradation reactions leading to the formation of polysaccharides. In both different seasons LDPE, HDPE, and BIO‐PE underwent partial biodegradation, remaining in the domestic composting as unwanted polymer debris. However, biodegradation in domestic composting is not recommended as feasible disposal routes for nonbiodegradable and commercially labeled as biodegradable PE.

Insertion of Unsaturated C-C Bonds into the O-H Bond of an Iridium(III)-Hydroxo Complex: Formation of Phosphorescent Emitters with an Asymmetrical β-Diketonate Ligand.

A synthetic methodology to prepare iridium(III) emitters of the class [3b+3b+3b'] with two ortho-metalated 1-phenylisoquinolines and an asymmetrical β-diketonate has been discovered. The abstraction of the chloride ligands of the dimer [Ir(μ-Cl){κ2-C,N-(C6H4-isoqui)}2]2 (1, C6H5-isoqui = 1-phenylisoquinoline) with AgBF4 in acetone and the subsequent addition of water to the resulting solution affords the water solvate mononuclear complex [Ir{κ2-C,N-(C6H4-isoqui)}2(H2O)2]BF4 (2), which reacts with KOH to give the dihydroxo-bridged dimer [Ir(μ-OH){κ2-C,N-(C6H4-isoqui)}2]2 (3). Treatment of the latter with dimethyl acetylenedicarboxylate leads to Ir{κ2-C,N-(C6H4-isoqui)}2{κ2-O,O-[OC(CO2CH3)CHC(OCH3)O]} (4), as a result of the anti-addition of the O-H bond of a mononuclear [Ir(OH){κ2-C,N-(C6H4-isoqui)}2] fragment to the C-C triple bond of the alkyne and the coordination of one of the carboxylate substituents to the metal center. Complex 3 also reacts with α,β-unsaturated ketones. The reaction with 3-(4-methylphenyl)-1-phenylprop-2-en-1-one affords Ir{κ2-C,N-(C6H4-isoqui)}2{κ2-O,O-[OC(C6H5)CHC(p-C6H4Me)O]} (5), whereas methyl vinyl ketone gives a mixture of Ir{κ2-C,N-(C6H4-isoqui)}2{κ2-O,O-[OC(CH3)CHCHO]} (6) and Ir{κ2-C,N-(C6H4-isoqui)}2{κ2-O,O-[OC(CH3)CHC(CH═CH2)O]} (7). Complexes 5 and 6 are the result of the addition of the O-H bond of the mononuclear [Ir(OH){κ2-C,N-(C6H4-isoqui)}2] fragment to the C-C double bond of the α,β-unsaturated ketones and the coordination of the carbonyl group to the iridium center, to generate O,O-chelates which lose molecular hydrogen to aromatize into the asymmetrical β-diketonate ligands. Complexes 4-7 are phosphorescent emitters in the red spectral region (599-672 nm) in doped poly(methyl methacrylate) (PMMA) film at 5 wt % at room temperature and 2-methyltetrahydrofuran at room temperature and 77 K. They display short lifetimes (0.8-2.5 μs) and quantum yields in both doped PMMA films and in 2-methyltetrahydrofuran at room temperature depending on the substituents of the β-diketonate: about 0.6-0.5 for 4 and 6 and ca. 0.35 for 5 and 7.

Deoxyuridine triphosphates modified with tyrosine or tryptophan aromatic groups for direct electrochemical detection of double-stranded DNA

Deoxyuridine triphosphates (dUTP) modified with tyrosine or tryptophan aromatic groups attached through –CH=CH–CH2–NH–C(O)–(CH2)n– linker at the C5 position of the pyrimidine ring and the corresponding products of polymerase chain reaction (PCR) were studied by cyclic and square wave voltammetry on carbon screen printed electrodes. A strong effect of the additional functional groups on the electrochemical activity of nucleotides was revealed. In particular, 5-aminoallyl-2′-deoxyuridine-5′-triphosphates modified with indole acetic, indole-3-propionic, indole-4-butyric, or 4-hydroxyphenylacetic acids demonstrated novel well-defined oxidation peaks at 0.5–0.7 V, similar to tryptophan or tyrosine amino acids, respectively. The oxidation potential maxima for dUTP derivatives under study were about 0.2–0.3 V less positive than the oxidation potential of dGTP (the most easily oxidizable nucleotide). Moreover, dUTP derivatives modified with tyrosine or tryptophan aromatic groups were incorporated by PCR into dsDNA fragments (amplicons) instead of dTTP. The PCR-generated dsDNA fragments with modified nucleotides were detected through the oxidation of their eleсtroactive ‘labels’ at micromolar concentrations, while no oxidation peaks were observed for unmodified amplicons under the same conditions. The tyrosine and tryptophan aromatic groups well complement the existing palette of electroactive tags for direct detection of nucleic acids. Compared to other electroactive ‘labels’, the main advantage of the developed oxidizable moieties is a good compatibility with polymerase enzymes including those used in PCR. In addition, the demonstrated signal recording procedure for modified amplicons on disposable carbon electrodes renders itself suitable for in situ analysis of biological samples for biochemical and medical applications.

3D-to-2D Dimensional Reduction for Exploiting a Multilayered Perovskite Ferroelectric toward Polarized-Light Detection in the Solar-Blind Ultraviolet Region.

Polarized-light detection in solar-blind ultraviolet region is indispensable for optoelectronic applications, whereas new 2D candidates targeted at solar-blind UV range remain extremely scarce. 2D hybrid perovskite ferroelectrics that combine polarization and semiconducting properties are of increasing interest. Here, using the 3D-to-2D dimensional reduction of CH3 NH3 PbCl3 , we designed a multilayered hybrid perovskite ferroelectric, (CH3 CH2 NH3 )2 (CH3 NH3 )2 Pb3 Cl10 , which shows spontaneous polarization and a high Curie temperature (390 K) comparable with that of BaTiO3 (393 K). The wide band gap (ca. 3.35 eV) and anisotropic absorbance stemming from its intrinsic 2D motif, greatly favor its polarization-sensitive activity in UV region. The device displays excellent polarization-sensitive behavior under 266 nm, along with a large dichroic ratio (ca. 1.38) and high on/off current ratio (ca. 2.3×103 ).

Theoretical reinvestigation of the ozonolysis mechanism of allyl alcohol

AbstractAllyl alcohol (AA) is the simplest unsaturated alcohol. Ozonolysis is one of the key removal processes for AA in the atmosphere. However, a recent theoretical study suggests that the ozonolysis of AA cannot feasibly occur in atmospheric conditions because of the high barrier (~96 kcal/mol) involved in the primary ozonide (POZ) decomposition. In this work, the ozonolysis mechanism of AA was reinvestigated theoretically. The computed barrier for POZ decomposition is only ~20 kcal/mol. Therefore, the AA ozonolysis can take place in the atmosphere, consistent with the experimental conclusions. Moreover, two new Criegee intermediates (syn‐ and anti‐AA‐CI) were found to be produced in this reaction. The wave function analyses indicate that there exists an intermolecular hydrogen bond in syn‐AA‐CI, which significantly affects its unimolecular decomposition and reactions with H2O. Compared with the normal reactions of anti‐CI‐AA, the stabilized syn‐AA‐CI has two distinct isomerization channels: (i) addition of OH group to the reactive sites of CI forming an ethylene oxide (HOOCH2OCH2) and (ii) double H‐transfer producing HOOCH2CHO. Meanwhile, the addition of H2O in syn‐AA‐CI also exhibits two different pathways. One is the unique addition‐coupled double H‐transfer, and the other is the addition‐coupled single H‐transfer, both leading to the formation of CH2(OH)CH(OH)OOH.

Cu Atomic Chain Supported on Graphene Nanoribbon for Effective Conversion of CO2 to Ethanol.

Cu catalysts are well-known for their good performance in CO2 conversion. Compared to CO and CH4 production, C2 products have higher volumetric energy densities and are more valuable in industrial applications. In this work, we screened the catalytic ability of C2 production on several 1D Cu atomic chain structures and find that Cu edge-decorated zigzag graphene nanoribbons (Cu-ZGNR) are capable of catalyzing CO2 conversion to ethanol, and CH3 CH2 OH is the main C2 product with a maximum free energy change of 0.60 eV. The planar tetracoordinate carbon structures in Cu-ZGNR provide unique chemical bonding features for catalytic reaction on the Cu atoms. Detailed mechanism analyses with transition states search show that CO* dimerization is favored against CHO* formation in the reaction. By adjusting the CO* coverage, the selectivity of the C2 product can be enhanced owing to less pronounced steric effects for COCHO*, which is feasible under experimental conditions. This study expands the catalyst family for C2 products from CO2 based on nano carbon structures with new features.

Radical channels of radiation destruction of macrocyclic component of strontium-selective extractants based on ionic liquids

To study the radiolysis of the extractant composition based on solutions of dicyclohexano-18-crown-6 (DCH18C6) in ionic liquids containing the bis(trifluoromethylsulfonyl)imide anion (NTf2−), we synthesized stereoisomeric DCH18C6•Sr(NTf2)2 complexes as a model of the strontium-containing macrocyclic component of this system and studied the mechanism of their destruction in the solid phase. Three main stages of radiation-chemical transformations were found. At the initial stage of radiolysis after ionization of the complex components, a positive charge is transferred from the macrocycle to the anion, which is induced by the lower ionization potential of NTf2− as compared to the crown ether. This results in the radiation protection of the macrocycle due to the blockage of the polyether ring cleavage, which is observed under radiolysis of “free” DCH18C6. The next stage consists in the accumulation of the —O—•CH—CH2— radicals caused by the reaction of the dissociation products of the NTf2− anion with the crown ether. It intensifies the radiation destruction of the polyether ring. At the final stage, the macrocyclic radicals efficiently scavenge SO2, the molecular product of dissociation of the NTf2− anion, with the formation of sulfonyl-type radicals. The discovered channels of radiation-chemical transformations of the macrocycle in the systems including the NTf2− anion should be considered in the design of new radiation-resistant extractants.

Nature of the Arsonium-Ylide Ph3 As=CH2 and a Uranium(IV) Arsonium-Carbene Complex.

Treatment of [Ph3 EMe][I] with [Na{N(SiMe3 )2 }] affords the ylides [Ph3 E=CH2 ] (E=As, 1As; P, 1P). For 1As this overcomes prior difficulties in the synthesis of this classical arsonium-ylide that have historically impeded its wider study. The structure of 1As has now been determined, 45 years after it was first convincingly isolated, and compared to 1P, confirming the long-proposed hypothesis of increasing pyramidalisation of the ylide-carbon, highlighting the increasing dominance of E+ -C- dipolar resonance form (sp3 -C) over the E=C ene π-bonded form (sp2 -C), as group 15 is descended. The uranium(IV)-cyclometallate complex [U{N(CH2 CH2 NSiPri 3 )2 (CH2 CH2 SiPri 2 CH(Me)CH2 )}] reacts with 1As and 1P by α-proton abstraction to give [U(TrenTIPS )(CHEPh3 )] (TrenTIPS =N(CH2 CH2 NSiPri 3 )3 ; E=As, 2As; P, 2P), where 2As is an unprecedented structurally characterised arsonium-carbene complex. The short U-C distances and obtuse U-C-E angles suggest significant U=C double bond character. A shorter U-C distance is found for 2As than 2P, consistent with increased uranium- and reduced pnictonium-stabilisation of the carbene as group 15 is descended, which is supported by quantum chemical calculations.

Highly active titanium(IV) dichloride FI catalysts bearing a diallylamino group for the synthesis of disentangled UHMWPE

A family of 16 salicylaldarylimine titanium(IV) dichloride complexes bearing diallylamino group, namely {2‐[3‐ or 4‐(CH2CHCH2)2NC6H4NCH]‐6‐R1‐4‐R2‐C6H2O}2TiCl2 (R1 = t‐Bu, CMe2(Ph); R2 = H, Me, OMe, t‐Bu) have been used for polymerization of ethylene in the presence of methylaluminoxane. The effects of reaction conditions on the polymerization were examined in detail. All the pre‐catalyst are highly active (up to 14.0 × 106 g(PE) mol(Ti)−1 −1 h−1) for ethylene polymerization at 30°С to 60°С with the activities and MM correlating with the R1‐substituent type and position of NAll2‐group: CMe2(Ph) &gt; t‐Bu and meta‐NAll2 &gt; para‐NAll2 for any R2. Highly linear polyethylenes (Tm's as high as 141.0°С) can be obtained with high molecular weights in the range 0.70 to 4.10 × 106 g mol−1 with disentangled morphology, suitable for technologically more advanced and greeny way to produce high‐modulus high‐strength fibers of ultrahigh molecular weight polyethylene via solid‐state (solvent‐free) deformation processing.