CH2OH Group Research Articles

Proton transfer driven by the fluctuation of water molecules in chitin film.

Proton-transfer mechanisms and hydration states were investigated in chitin films possessing the functionality of fuel-cell electrolytes. The absolute hydration number per chitin molecule (N) as a function of relative humidity (RH) was determined from the OH stretching bands of H2O molecules, and the proton conductivity was found to enhance above N = 2 (80%RH). The FIR spectrum at 500-900cm-1 for 20%RH (N < 1) together with first-principles calculations clearly shows that the w1 site has the same hydration strength as the w2 site. The molecular dynamics simulations for N = 2 demonstrate that H2O molecules with tiny fluctuations are localized on w1 and w2, and the hydrogen-bond (HB) network is formed via the CH2OH group of chitin molecules. Shrinkage of the O-O distance (dOO), which synchronizes with the barrier height, is required for proton transfer from H3O+ to adjacent CH2OH groups or H2O molecules. Nevertheless, dOO is hardly modulated for N = 2 because H2O molecules are strongly constrained on w1 and w2, and therefore, the transfer probability becomes small. For N = 3, novel HBs emerged between the additional H2O molecules broadly distributed on the w3 site and H2O molecules on w1 and w2. The transfer probability is enhanced because large fluctuations and diffusions in the whole H2O molecule yield large modulations of dOO. Consequently, long-range proton hopping is driven by the Zundel-type protonated hydrates in the water network.

Synthesis of phenolic resins with cyclotriphosphazene for enhancement of ablation and char yields

A novel phenolic resin with combined hydroxymethyl-substituted phosphazene unit as a part of cured network was prepared which exhibited excellent thermal properties and ablation resistance. The novel phenolic resin was synthesized via copolymerizing from hexa (4-hydroxymethylphenoxy) cyclotriphosphazene (CHPP), phenol and paraformaldehyde. The CHPP contains abundant –CH2OH groups, which can be a part of phenolic resin network through condensation reactions between the –CH2OH groups and active hydrogens on benzene rings of phenolic resins. The optimal curing temperature for the modified phenolic resins was determined using the non-isothermal DSC method. The ablation resistance was investigated using the oxyacetylene flame method. The char yield and linear ablation rate of the modified phenolic resins are 71.3 % and 0.0020 mm/s, respectively. The ablation resistance of the novel resin is significantly improved, compared with other phenolic resin composites. The modification method for the phenolic resin provides a novel pathway to improve the application prospects of phenolic resins in the field of thermal protective materials.

Energetics of the OH radical H-abstraction reactions from simple aldehydes and their geminal diol forms.

Carbonyl compounds, especially aldehydes, emitted to the atmosphere, may suffer hydration in aerosols or water droplets in clouds. At the same time, they can react with hydroxyl radicals which may add or abstract hydrogen atoms from these species. The interplay between hydration and hydrogen abstraction is studied using density functional and quantum composite theoretical methods, both in the gas phase and in simulated bulk water. The H-abstraction from the aldehydic and geminal diol forms of formaldehyde, acetaldehyde, glycolaldehyde, glyoxal, methylglyoxal, and acrolein is studied to determine whether the substituent has any noticeable effect in the preference for the abstraction of one form or another. It is found that abstraction of the H-atom adjacent to the carbonyl group gives a more stable radical than same abstraction from the geminal diol in the case of formaldehyde, acetaldehyde, and glycolaldehyde. The presence of a delocalizing group in the Cα (a carbonyl group in glyoxal and methylglyoxal, and a vinyl group in acrolein), reverts this trend, and now the abstraction of the H-atom from the geminal diol gives more stable radicals. A further study was conducted abstracting hydrogen atoms from the other different positions in the species considered, both in the aldehydic and geminal diol forms. Only in the case of glycolaldehyde, the radical formed by H-abstraction from the -CH2OH group is more stable than any of the other radical species. Abstraction of the hydrogen atom in one of the hydroxyl groups in the geminal diol is equivalent to the addition of the •OH radical to the aldehyde. It leads, in some cases, to decomposition into a smaller radical and a neutral molecule. In these cases, some interesting theoretical differences are observed between the results in gas phase and (simulated) bulk solvent, as well as with respect to the method of calculation chosen. DFT (M06-2X, B2PLYP, PW6B95), CCSD(T), and composite (CBS-QB3, jun-ChS, SCVECV-f12) methods using Dunning basis sets and extrapolation to the CBS limit were used to study the energetics of closed shell aldehydes in their keto and geminal-diol forms, as well as the radical derived from them by hydrogen abstraction. Both gas phase and simulated bulk solvent calculations were performed, in the last case using the Polarizable Continuum Model.

Gradual or Hysteretic Transition: Anion Effects on Cobalt(II) Spin Crossover Complexes

Comprehensive SummaryTo better understand the impact of different anions on the structures and SCO properties of the CoII SCO complexes, six new complexes [Co(terpy‐CH2OH)2]A2·sol (terpy‐CH2OH = 4′‐(hydroxymethyl)‐2,2′;6′,2″‐terpyridine, A = Br– (1, sol = 1.5H2O), I– (2), N3– (3, sol = 2H2O), H3BCN– (4), OTf– (5), and TsO– (6, sol = 4H2O·CH3CN), have been synthesized and characterized. All six compounds consist of mononuclear [Co(terpy‐CH2OH)2]2+ cations and charge‐balancing anions that differ in size, shape, and hydrogen bonding capacity. Complexes 1, 2, 3, and 6 displayed incomplete gradual SCO transitions, whereas 4 and 5 exhibited abrupt hysteretic spin transitions with loops of 12 and 16 K (250.0—262.0 K for 4, and 370.0—386.0 K for 5, respectively), closely resembling our previously reported complexes with SCN– and SeCN– anions. The occurrence of the order‐disorder transition of the CH2OH groups and their transition temperatures are determined by the size and hydrogen bonding capability of the anions. Remarkably, the transition temperatures of complexes with H3BCN–, SCN–, OTf–, and SeCN– anions exhibit an upward trend as the size and mass of the anions increase, as confirmed through detailed single crystal structure analyses conducted in both high‐spin and low‐spin states for all four complexes.

Hydrophobic interactions described using hetero-segmented PC-SAFT: 1. Alcohol/water mixtures

The hydrophobic effect plays a central role in aqueous systems containing molecules with hydrophobic moieties. Despite the relevance of this effect for chemical processes or pharmaceutical applications, modeling remains challenging even using molecular-based models such as different versions of the Statistical Associating Fluid Theory. This work shows the feasibility of hetero-segmented PC-SAFT for this purpose. This model was used as a group contribution method to build molecules from different functional groups, namely from CH2, CH3, and CH2OH groups. Saturated-liquid densities and vapor pressures of n-alkanes and n-alcohols as well as binary mixtures of these molecules were accurately described by this approach. The description of aqueous mixtures containing n-alkanes and n-alcohols was improved compared to state-of-the-art modeling by explicitly accounting for intermolecular interactions resulting in the hydrophobic effect. The so-obtained framework describes the two liquid−liquid equilibrium phases in mixtures of n-alkanes or n-alcohols with water equally well using a single set of transferable parameters. The model was also validated for vapor–liquid equilibria, solid–liquid equilibria, infinite-dilution properties, as well as octanol/water partition coefficients and showed quantitative agreement with experimental data.

Coordination of Palladium with Polydentate Non‐planar Ligands with Competitive Donors (Oxygen and Double Bonds). Role of Stereochemistry

AbstractPalladium (II) complexes of three polydentate non‐planar bicyclo[4.4.0]decane ligands with at least one double bond and bridgehead cis‐substituents CH2OH or CH2OCH2 were prepared in order to investigate the role of stereochemistry and donor nucleophilicity in the Pd coordination. All ligands and their corresponding complexes were characterized using NMR, solid‐state NMR (ssNMR), HR‐MS, ATR‐IR, DSC‐TGA. For ligand cis‐1,4,5,8‐tetrahydro‐naphthalene‐4a,8a‐diyl‐dimethanol (L2) the X‐ray structure corresponded to the DFT optimised structure. The HR‐MS and thermal analysis data confirmed a complexation ratio: ligand/PdCl2 of 1/1. The experimental data as well as the computations are consistent with the structures proposed based on 13C‐ssNMR, namely palladium coordinates with one double bond and an oxygen atom for ligands with CH2OH groups and with both double bonds for the ligand with an etheric bridge, showing the prevalence of stereochemistry over donor nucleophilicity for such non‐planar ligands.

Synergistic promotion of oxygen vacancy and Lewis acidity of Nb2O5 on the preferential hydroxymethyl hydrogenolysis of 5-hydroxymethylfurfural catalyzed by single atom Pt

Over Pt1/Nb2O5, oxygen vacancy increases the catalytic activity, while the strong Lewis acidity of Nb2O5 selectively promotes the hydrogenolysis of the –CH2OH group rather than the hydrogenation of the –CHO group.

Effect of alkali metals on physical and spectroscopic properties of cellulose

A 3-unit cellulose model molecule was built and optimized using DFT B3LYP/6-31G(d,p). The electronic properties of the optimized structure of cellulose were investigated in terms of total dipole moment (TDM), HOMO–LUMO band gap (ΔE), and molecular electrostatic potential (MESP). Cellulose demonstrated a TDM of 9.106 Debye and ΔE of 7.647 eV. The hydrogen atom of the hydroxyl group of the CH2OH group of each cellulose unit was replaced by an alkali metal atom (X) such that the 3-unit cellulose once had 1X atom, then 2X, then 3X atoms, where X = Li, Na or K, both without and with 2, 4 and 6 water molecules (W), respectively, to study also the effect of hydration. Without hydration, the values of TDM decreased for all of the proposed interaction, but increased with hydration, while ΔE decreased in all interactions, confirming that interaction cellulose-alkali metal interaction, especially with hydration, resulted in more reactive structures. Mapping of HOMO–LUMO and MESP indicated significant change in the electron density distribution around cellulose under the effect of interaction with the alkali metals, both with and without hydration. The plots of projected density of states also clearly demonstrated the contribution of each alkali metal as well as water in the molecular orbitals, reflecting their effect on the electronic properties of cellulose and cellulose-alkali metals composites. The theoretical calculations were experimentally verified using FTIR and FT-Raman spectroscopy.

Starch Assisted the ZnS Buffer Layer in Enhancing the Photoluminescence of ZnSe/ZnS:Mn/ZnS Quantum Dots for Detecting E. Coli and MRSA Bacteria Quickly.

In this study, we used a starch paste stabilizer to synthesize ZnSe: Mn/ZnS- Starch and ZnSe/ZnS: Mn/ZnS-starch quantum dot (QDs) in a non-toxic aqueous solvent. The -CH2-OH group of the starch paste promotes dispersibility and improves the compatibility of quantum dots with antibodies, its bonding is observed in the FTIR spectrum. Besides, the Mn-doped ZnS buffer shell with various concentrations (1, 3, 5, 7, and 9%) influence structure, optical, and photoluminescence of QDs properties were investigated in detail. The greatest luminescence intensity is achieved at a molar ratio of 3% Mn2+/Zn2+. Moreover, the ZnS: Mn buffer shell helps to enhance the fluorescence intensity and quantum yield (QY) of the ZnSe/ZnS: Mn/ZnS QDs, which are higher than ZnSe: Mn/ZnS-starch QDs. Through protein A and EDC bridging, ZnSe/ZnS:3%Mn/ZnS- Starch resulted in good signal and sensitivity, with no toxicity to E. coli O157:H7 and MRSA strains.

Monolayers of amino acid-type amphiphiles

The monolayer characteristics of selected N-alkanoyl substituted α-amino acid are studied with the objective to demonstrate the specific effect of the chemical structure of the polar head group which is highlighted with the D- and L-enantiomers of the following selected examples: R-alanine, R-serine, R-threonine, R-allo-threonine, and R-aspartic acid (R = C16, C18). The thermodynamic effect of the head group variation is studied. Experimental π-A isotherms of the N-tetradecyl-L-alanine monolayers show similar behavior as those of usual amphiphiles. The -CH3-group in R-alanine with the simplest head group structure is substituted by a -CH2-OH group in R-serine and serine methylester and by a -CH- CH3-OH group in R-threonine (or allo-threonine) and threonine methylester. The introduction of the methyl group in 3-position of serine (serine to 3-methyl-serine = threonine) shifts the characteristic temperatures by >20 K to lower values determined for N-C16-Dl-serine. The formation of the corresponding methylester decreases these temperatures by 15 K for serine with the shorter (C16) alkyl chain and only by ∼5 K for threonine with the longer chain (C18). The π–A curves of the enantiomeric and racemic allo-forms show similar features to those of N-stearoyl-threonine. The absolute T0-values (disappearance of the LE/LC-transition) are 4–5 K larger compared with the corresponding N-stearoyl-threonines, but the ΔT0 between the enantiomeric (D) and the racemic (DL) forms is only slightly larger than that of N-stearoyl-threonine.Monolayers of different N-alkanoyl substituted α-amino acid amphiphiles have been mesoscopically characterized. Substantial topological differences are observable at the condensed phase domains of several amino acid amphiphiles, such as, N-palmitoyl aspartic acid, N-palmitoyl- or N-stearoyl serine methyl ester, N-stearoyltyrosine, N-palmitoyl or N-myristoyl alanine. Many fascinating domain shapes are found, but always the curvatures of the two enantiomeric forms are directed in an opposite sense. The domain shape of the 1:1 racemic mixtures is usually different, but very often oppositely curved texture elements are observable.GIXD is used to study the characteristic features of the lattice structure of condensed monolayer phases on the Angstrom scale. Specific for all structures is the large tilt angle with respect to the surface normal, which decreases only marginally by compression. The large size of the head groups and strong interactions between them dominate the monolayer structure. As presented for NC16 and N-C18-threonine, N-C16-DL -serine, N-C16-L -serine, NC16 DL -serine-ME, NC16 L -serine-ME, NC18 DL -threonine-ME, and NC18 L -threonine-ME the enantiomers form an oblique lattice structure (3 diffraction peaks), whereas two peaks are observed for the racemates forming NNN tilted orthorhombic structures. A complete phase diagram of mixed monolayers of the D- and L-enantiomers of N-stearoyl-threonine with two eutectic points at xD ≈ 0.25 and xD ≈ 0.75 is proposed.The quantum chemical semiempirical PM3 method is applied to calculate the thermodynamic and structural parameters of clusterization in finite and infinite clusters for N-alkanoyl-substituted alanine with n = 8–17 carbon atoms in the chain at the air/water interface with the aim to obtain a new theoretical verification of the experimental results.

Producing Polyurethane as Wound Plaster using Glycerol Transesterified of Waste Cooking Oil with Moringa Leaf Extract (Moringa Oleifera Lam.) as an Antimicrobial

Wound plaster polyurethane can make using glycerol from waste cooking oil (WCO). Wound plasters should contain antibacterial ingredients in addition to covering the sore. Traditionally various plants have been used to treat sore and contain sundry antibacterial chemical compounds amid Moringa oleifera Lam. Therefore, it is very potential to make polyurethane wound plasters from glycerol produced from WCO combined with Moringa leaf extract obtained from wound plasters from natural ingredients. Maceration with 96 % ethanol yielded moringa leaf extract. Then, a transesterification reaction carries out by using KOH-methanol at 60 °C to get glycerol and tested by FTIR spectrophotometry. Polyurethane wound plasters were made with a mixture of methylene 4,4 diphenyl diisocyanate, polyethylene glycol (PEG) and various formulas with variations of glycerol 0, 3, 6, 9, 12, 15 and 18 drops. A characteristic test enforced with swelling test to find the best formula and functional group analysis using FTIR spectrophotometry. Into the best wound plaster, improved Moringa leaf ethanol extract at an intensity of 1 - 5 %. An antibacterial activity test carries out on the Moringa leaf ethanol extract and plasters obtained by the agar diffusion method. The FTIR spectrophotometer test showed the formation of glycerol from WCO. The results of the characteristics test for polyurethane wound plaster preparations obtained the best formula using 3 drops of glycerol. The antibacterial activity test results at a concentration of 500 mg/mL Moringa leaf extract produced a muscular inhibition zone of 19.2 mm against Staphylococcus aureus and Antiseptic solution of 17.3 mm; Pseudomonas aeruginosa of 14.3 mm and Antiseptic solvent of 16.2 mm. Antibacterial activity of polyurethane wound plaster against Staphylococcus aureus contains 5 % ethanol extract of 10.3 mm, Plaster Merck X of 11.2 mm, Pseudomonas aeruginosa, only gave resistance at 5 % concentration of 8.3 mm and Plaster Merck X of 9.2 mm. HIGHLIGHTS Based on FTIR testing, it confirms the presence of aliphatic CH groups and OH groups, as well as the comparison of FTIR spectra with the raw material indicates the presence of Glycerol from Transesterification of Used Cooking Oil, and then the purification process of glycerol from used cooking oil yielded 30.4 g Glycerol from the transesterification reaction of WCO is used to create polyurethane wound dressings by forming urethane groups (-NHCO), as indicated by the FTIR results of the best formula using 3 drops of glycerol The Moringa leaf extract in the polyurethane wound dressing formula shows antibacterial activity GRAPHICAL ABSTRACT

Hysteretic Spin Crossover with High Transition Temperatures in Two Cobalt(II) Complexes.

Cooperative spin crossover transitions with thermal hysteresis loops are rarely observed in cobalt(II) complexes. Herein, two new mononuclear cobalt(II) complexes with hysteretic spin crossover at relatively high temperatures (from 320 to 400 K), namely, [Co(terpy-CH2OH)2]·X2 (terpy-CH2OH = 4'-(hydroxymethyl)-2,2';6',2″-terpyridine, X = SCN-(1) and SeCN- (2)), have been synthesized and characterized structurally and magnetically. Both compounds are mononuclear CoII complexes with two chelating terpy-CH2OH ligands. Magnetic measurements revealed the existence of the hysteretic SCO transitions for both complexes. For compound 1, a one-step transition with T1/2↑= 334.5 K was observed upon heating, while a two-step transition is observed upon cooling with T1/2↓(1) = 329.3 K and T1/2↓(2) = 324.1 K (at a temperature sweep rate of 5 K/min). As for compound 2, a hysteresis loop with a width of 5 K (T1/2↓ = 391.6 K and T1/2↑ = 396.6 K, at a sweep rate of 5 K/min) can be observed. Thanks to the absence of the crystallized lattice solvents, their single crystals are stable enough at high temperatures for the structure determination at both spin states, which reveals that the hysteretic SCO transitions in both complexes originate from the crystallographic phase transitions involving a thermally induced order-disorder transition of the dangling -CH2OH groups in the ligand. This work shows that the modification of the terpy ligand has an important effect on the magnetic properties of the resulting cobalt(II) complexes.

6-[(2S,3R)-3-(2,4-Difluorophenyl)-3-hydroxy-4-(1H-1,2,4-triazol-1-yl)butan-2-yl]-5-fluoropyrimidine-4-carbaldehyde

Voriconazole (VN) is an antifungal drug indicated for the treatment of several fungal infections. Due to its side effects, some works involving late-stage functionalization of VN have been reported in the literature. Here, we disclose a new VN derivative, the 6-[(2S,3R)-3-(2,4-difluorophenyl)-3-hydroxy-4-(1H-1,2,4-triazol-1-yl)butan-2-yl]-5-fluoropyrimidine-4-carbaldehyde (VN-CHO). This compound results from the photoredox-catalyzed hydroxymethylation of VN, affording a hydroxymethylated derivative (VN-CH2OH), followed by oxidation of the former CH2OH group. VN-CHO was obtained in good yield (70% yield) and its structure was unveiled by 1D (1H and 13C) and 2D (HSQC and HMBC) NMR techniques. The introduction of a formyl group in VN structure creates a very promising site for further functionalization in a molecule which originally does not have many active sites.

Mechanistic Insight into Favorable Aldehyde Hydrogenation over Hydroxymethyl Hydrogenolysis in 5-Hydroxymethylfurfural by Formic Acid over Single-Atom Co-N3/C

Although the Co–N–C catalyst exhibits good catalytic performance toward the hydrogenation of 5-hydroxymethylfurfural (HMF) with formic acid (FA) as the H source, its catalytic mechansim is still unclear at the molecular level, including competitive hydrogenation of the aldehyde (−CHO) group and hydrogenolysis of the hydroxymethyl (−CH2OH) group. Here, a single-atom Co-N3/C surface was modeled as a Co–N–C catalyst with an armchair model of activated carbon support. Over Co-N3/C, the catalytic mechanism for the hydrogenation/hydrogenolysis of HMF with FA has been theoretically investigated in 1,4-dioxane solution at the GGA-PBE/DNP level. The hydrogenation product, i.e., 2,5-dihydroxymethylfuran (DHMF), should be predominant, whereas the hydrogenolysis products, i.e., 5-methylfurfuryl alcohol (5-MFA), 5-methylfurfural (5-MF), and 2,5-dimethylfuran (DMF), should be minor. The rate-determining steps are concerned with the cleavage of the C–H bond in the FA moiety through an intermolecular H-shift. For the crucial transition states, compared with the Co–C group in the hydrogenolysis of the −CH2OH group, the Co–O–C group in the hydrogenation of the −CHO group can more efficiently promote the cleavage of the C–H bond in the FA moiety, which stems from the electrophilic properties of aldehyde oxygen. Kinetically, Co-N3/C boosts the hydrogenation of the −CHO group to a −CH2OH group and selectively hampers the hydrogenolysis of the −CH2OH group to a −CH3 group.

Identification of potential biomarkers for colorectal cancer by clinical database analysis and Kaplan-Meier curves analysis.

This study aimed to explore critical genes as potential biomarkers for the diagnosis and prognosis of colorectal cancer (CRC) for clinical utility. To identify and screen candidate genes involved in CRC carcinogenesis and disease progression, we downloaded microarray datasets GSE89076, GSE73360, and GSE32323 from the GEO database identified differentially expressed genes (DEGs), and performed a functional enrichment analysis. A protein-protein interaction network was constructed, and correlated module analysis was performed using STRING and Cytoscape. The Kaplan-Meier survival curve shows the survival of the hub genes. The expression of cyclin-dependent kinase (CDK1), cyclin B1 (CCNB1), and PCNA in tissues and changes in tumor grade were analyzed. A total of 329 DEGs were identified, including 264 upregulated and 65 downregulated genes. The functions and pathways of DEGs include the mitotic cell cycle, poly(A) RNA binding replication, ATP binding, DNA replication, ribosome biogenesis in eukaryotes, and RNA transport. Forty-seven Hub genes were identified, and biological process analysis showed that these genes were mainly enriched in cell cycle and DNA replication. Patients with mutations in CDK1, PCNA, and CCNB1 had poorer survival rates. CDK1, PCNA, and CCNB1 were significantly overexpressed in the tumor tissues. The expression of CDK1 and CCNB1 gradually decreased with increasing tumor grade. CDK1, CCNB1, and PCNA can be used as potential markers for the diagnosis and prognosis of CRC. These genes are overexpressed in colon cancer tissues and are associated with low survival rates in CRC patients.

Combining Polymerization and Templating toward Hyper-Cross-Linked Poly(propargyl aldehyde)s and Poly(propargyl alcohol)s for Reversible H2O and CO2 Capture and Construction of Porous Chiral Networks.

Two series of hyper-cross-linked microporous polyacetylene networks containing either -[CH=C(CH=O)]- or -[CH=C(CH2OH)]- monomeric units are reported. Networks are prepared by chain-growth copolymerization of acetal-protected propargyl aldehyde and acetal-protected propargyl alcohol with a 1,3,5-triethynylbenzene cross-linker followed by hydrolytic deprotection/detemplating. Deprotection not only liberates reactive CH=O and CH2OH groups in the networks but also modifies the texture of the networks towards higher microporosity and higher specific surface area. The final networks with CH=O and CH2OH groups attached directly to the polyene main chains of the networks have a specific surface area from 400 to 800 m2/g and contain functional groups in a high amount, up to 9.6 mmol/g. The CH=O and CH2OH groups in the networks serve as active centres for the reversible capture of CO2 and water vapour. The water vapour capture capacities of the networks (up to 445 mg/g at 297 K) are among the highest values reported for porous polymers, making these materials promising for cyclic water harvesting from the air. Covalent modification of the networks with (R)-(+)-3-aminopyrrolidine and (S)-(+)-2-methylbutyric acid enables the preparation of porous chiral networks and shows networks with CH=O and CH2OH groups as reactive supports suitable for the anchoring of various functional molecules.

Tris-decorated multi-iron polyoxotungstates.

Solution-stable tris(hydroxymethyl)aminomethane-functionalized FeIII-containing polyoxotungstates exhibit an unusual anchoring mode of triol moieties, with one -NH2 and one -CH2OH group remaining accessible for post-functionalization or chemisorption. The redox-active title compounds have been isolated under unusually mild reaction conditions and characterized in the solid state and in aqueous solutions.

Желатиннің композициялық үлдірлерінің құрылымдық-механикалық қасиеттері

The deformation properties, elastic modulus and strength of gelatin films with chitosan, citric acid and L-glutamic acid were studied. According to the results of the study, it was found that the addition of chitosan, citric and L-glutamic acid increases the strength and elasticity modulus of gelatin films. Assessment of the pH effect on the gelatin - chitosan, gelatin - citric acid and gelatin - L-glutamic acid systems provide a representation of their changes in these media. It is assumed that gelatin with L-glutamic acid forms a strong structure at low pH and withstands the conditions of the acidic environment of the stomach, while in an alkaline environment the structural and mechanical characteristics of this system decrease, creating favorable conditions for the release of encapsulated insulin in the intestinal phase. The changes of the physicochemical, structural and mechanical properties of the films under simulated gastrointestinal conditions (pH = 1.0; 4.01; 6.86; 9.18) were determined by IR spectroscopy. The observability of the bands of С-Н, С-ОН, С=O, C-N, N-H, СН(NH2), CH2OH groups in the infrared spectra of films in various pH media is associated with an increase of intermolecular hydrogen bonds and the formation of associative structures.

Intrinsic Hydrogen‐Bond Donors‐Lined Organophosphate Superionic Nanochannels Levering High‐Rate‐Endurable Aqueous Zn Batteries

AbstractOrganic/inorganic hybrid artificial functional layer (AFL) designs of Zn anode have witnessed good progress in stabilizing the Zn anode. However, such processes remain uncapable of simultaneously providing durable protection and fast Zn2+migration, especially in high‐rate scenarios. Herein, intrinsic hydrogen‐bond donor (HBD)‐lined organophosphate superionic nanochannels are initially engineered to address this challenge. Due to unique ordered nanochannels with a smaller diameter than that of hydrated Zn2+ions and polyanions, hydroxymethyl Zn phosphates (Zn(O3PCH2OH, ZnOPC) are first considered for AFL design. The small size can provide an interception for polyanions. Density functional theory calculation indicates that ZnOPC nanochannels possess a 35% lower Zn2+migration energy barrier than conventional Zn phosphate, highly consistent with tested results. Additionally, as HBDs, rich ‐CH2OH groups located at nanochannels impose a targeted hydrogen‐bonding interaction with water molecules. Consequently, at an ultrahigh current density up to 50 mA cm−2, the Zn@ZnOPC anode shows a 36% lower overpotential than that of the bare Zn anode. As‐assembled Zn @ ZnOPC//NaV3O8· 1.5H2O full cells exhibit an ultralong lifespan of 20 000 cycles at 20 A g−1, with a low capacity‐decay of 0.016% per cycle. This work features a targeted hydrogen bonding‐enhanced desolvation effect occurring in organophosphate superionic nanochannels, which would enlighten to explore reliable fast‐charging aqueous batteries.

[3 + 2] Cycloaddition reactions of nitrile oxides generated in situ from aldoximes with alkenes and alkynes under ball-milling conditions

ABSTRACT A convenient and efficient [3 + 2] cycloaddition reaction of alkenes and alkynes with the in situ generated nitrile oxides from aldoximes in the presence of NaCl, Oxone and Na2CO3 has been developed to afford a series of isoxazoles and isoxazolines at room temperature in yields up to 85% and 86%, respectively. The current methodology exhibits a wide substrate scope, (hetero)aromatic and aliphatic aldoximes, alkenes including acrylate esters, acrylonitrile, chalcone, styrene, N-methylmaleimide and [60]fullerene, phenylacetylene, and alkynes containing CH2OH, SiMe3, COCH3 or CO2CH3 group can be employed. The present protocol features good functional group tolerance, short reaction time, mild reaction conditions and high atom economy, providing an efficient and environmentally friendly access to isoxazoles and isoxazolines.