A novel impedance immunosensor based on O-phenylenediamine modified gold electrode to analyze abscisic acid

An impedance immunosensor based on O-phenylenediamine modified gold electrode for the determination of phytohormone abscisic acid(ABA) was proposed.The operating pH,absorption time,absorption temperature and concentration of anti-ABA antibody were investigated to optimize the analytical performance.The calibration curve for the determination of ABA was obtained from this impedance immunosensor under optimal conditions.The results showed that the detection limit at about 1 ng/mL in the range of 10-5000 ng/mL...

Electropolymerization of O-Phenylenediamine in an Ionic Liquid

Ionic liquid like 1-ethyl-3-methylimidazolium bromine ([EMIM]Br) has been used as electrolyte for the electropolymerization of O-phenylenediamine at glassy carbon electrode by cyclic voltammetry. It is found that poly (O-phenylenediamine) film modified electrode has favorable electrochemical activity in acid solution.

Polymerization of o-Phenylenediamine Catalyzed byHemeproteins Encapsulated in Reversed Micelle

Hemeproteins encapsulated in reversed micelle formulated with di-2-ethylhexyl sulfosuccinate(AOT) was found to catalyze the polymerization of o-phenylenediamine(o-PDA) with hydrogen peroxide, whereas o-PDA catalyzed by hemeproteins dissolved in water could only form its trimers. As the nanostructural environment in reversed micelle acts as a certain orientation surrounding medium, it offers a strong electrostatic field that alters the reductive potential of Fe 3+/Fe 2+(E m7) in the heme of hemeproteins and thus increases the catalytic activity of peroxidase accordingly. According to the results of UV-Vis, 1H NMR and FTIR, the polymer catalyzed by hemoglobin(Hb) in reversed micelle was presumed to be constructed of lines and trapeziforms alternatively.

Studies on the Reaction Between α－Acetylthioformanilide and o-Phenylenediamine

,3-Disubstituted quinoxalines were synthesized from α-acetylthioformanilide and ophenylenediamine. Further studies sliowed that there existed competitive re- actions. One was a condensation reaction which produced substituted quinoxaline and the other was a substitution reaction which produced substituted quinoxaline-2- thione.

THE REACTION OF ETHYL AROYLACETATES AND o-PHENYLENEDIAMINE

Instead of 2-(aroylmethylene)benzimidazolines 3 or 2-(aroyl-methyl)benzimidazoles 4, 4-aryl-2, 3-dihydro-1H-1, 5-benzodiazepin-2-ones 5 were obtained exclusively from the reaction of o-phenylenediamine (1) and ethyl aroylacetates 2 in the presence of a catalytic amount of potassium hydroxide.

Crosslinking Mechanism of Soy Protein-based Adhesives based on Glyoxal and a Compound of Protein Model

The crosslinking mechanism of glyoxal and asparagine was analyzed,and the relationship between the mechanism and practical performances of soy protein-based adhesives was also discussed.It is shown that when pH=1 and 3,glyoxal reacted with asparagine in the form of major cyclic ether compounds.When pH=5,glyoxal reacted with asparagine in two structural forms of sodium glycollate and cyclic ether compounds.However,amidogens of asparagine were easy to develop protonation under acid conditions.Supplemented by the instability of cyclic ether compounds,the reaction activity and reaction degree between glyoxal and asparagine were relatively small.Under alkaline conditions,glyoxal mainly reacted with asparagine in the form of sodium glycollate.With the increase of pH,the polycondensation was more sufficient and the produced polycondensation products were more stable.The reaction mechanism between glyoxal and asparagine had strong correspondence to the practical performances of the adhesives.Glyoxal solution could develop crosslinking reactions with soy protein under both acid and alkaline conditions.Bonding strength and water resistance of the prepared soy protein-based adhesives were increased significantly.When pH>7,glyoxal had relatively high reaction activity and reaction intensity with soy protein,and the prepared adhesives had high crosslinking density and cohesion strength,showing relatively high bonding strength,water resistance and thermal stability.

Theoretical Studies on Mechanism and Rate Constant of Gas Phase Hydrolysis of Glyoxal Catalyzed by Sulfuric Acid

The gas phase hydration of glyoxal （HCOCHO） in the presence of sulfuric acid （H2SO4） were studied by the high-level quantum chemical calculations with M06-2X and CCSD（T） theoretical methods and the conventional transition state theory （CTST）. The mechanism and rate constant of the five different reaction paths are consid- ered corresponding to HCOCHO＋H2O, HCOCHO＋H2O… H2O, HCOCHO… H2O＋H2O, HCOCHO＋H2O… H2SO4 and HCOCHO… H2O＋H2SOa. Results show that H2SO4 has a strong catalytic ability, which can significantly reduce the energy barrier for the hydration reaction of glyoxal. The energy barrier of hydrolysis of glyoxal in gas phase is lowered to 7.08 kcal/mol from 37.15 kcal/mol relative to pre-reactive complexes at the CCSD（T）/6- 311＋＋G（3df, 3pd）//M06-2X/6-311＋＋G（3df, 3pd） level of theory. The rate constant of the H2SO4 catalyzed hydrolysis of glyoxal is 1.34×10-11 cm3/（molecule.s）, about 1013 higher than that involving catalysis by an equal number of water molecules, and is greater than the reaction rate of glyoxal reaction with OH radicals of 1.10×10-11 cm3/（molecule·s） at the room temperature, indicating that the gas phase hydrolysis of glyoxal of H2SO4 catalyst is feasible and could compete with the reaction glyoxal＋OH under certain atmospheric condi- tions. This study may provide useful information on understanding the mechanistic features of inorganic acid-catalyzed hydration of glyoxal for the formation of oligomer.

Oxidation of glyoxal to glyoxylic acid by oxygen over V_2O_5/C catalyst

A novel vanadium oxide catalyst supported on active carbon was prepared by an incipient wetness impregnation method, and the precursor was obtained from oxalic acid aqueous solutions of NH4VO3. The catalyst was applied liquid phase oxidation of glyoxal to glyoxylic acid. It was found that V2O5/C catalyst exhibited obvious activity for glyoxal oxidation. Glyoxylic acid could be obtained without pH regulation during the reaction. By using this catalyst, the conversion of glyoxal and the yield of glyoxalic acid were 29.2% and 13.6%, respectively at 313 K and oxygen flow 0.1 L/rain after reaction for 10 h.

Study on the Soy Protein-Based Adhesive Cross-Linked by Glyoxal

Based on the ESI-MS and ^(13)C-NMR analysis of the forms of glyoxal in acidic and alkaline solutions,the soy-based adhesive cross-linked by glyoxal was prepared in this work.The results showed that glyoxal existed in water in different forms at different pH levels.Under alkaline conditions,glyoxal transformed to glycolate through the intramolecular disproportionation reaction.Under acidic conditions,although some of glyoxal transformed to glycolate as what happened under alkaline conditions,most of glyoxal molecules existed in the form of fiveor six-membered cyclic ether structure.No ethylene tetraol or free aldehyde group was actually detected under these conditions.Although glyoxal reacted with soy protein under both acidic and alkaline conditions,alkaline conditions were more favorable for the improvement of mechanical performance and water resistance of soybased adhesives than acid conditions.

Study on Various Compositions of Polyvinyl Alcohol and Starch Blends by Cross-Linking with Glyoxal

The aim of this study is to analyze the various compositions of polyvinyl alcohol (PVA) and starch blends. The blends have been cross-linked with glyoxal to enhance its properties. The hydroxyl groups of PVA and starch react with glyoxal via formation of acetal bonds;hence crosslinking could take place. The cross-linking of glyoxal is observed in various analytical methods such as DSC and FTIR. The cross-linked blends showed better thermal and mechanical properties. Viscosity, tensile shear strength, pencil hardness and ultimate stress were evaluated to estimate the changes due to cross-linking. It was observed that the cross-linking is directly proportional to starch, since the starch hydroxyl groups are easily accessible for reacting. The cross-linked blend showed better cohesion between its chains, thereby increasing glass transition temperature. It was reflected in the subsequent increase in tensile strength properties.

Chlorine-radical Induced Oxidation of Glyoxal and Glyoxal-S(IV) Adducts in the Aqueous Phase

A laser flash photolysis study of the reactivity of Cl˙with glyoxal, glyoxal mono- and dibisulfite adducts, 1-hydroxy-2, 2-diol-ethanesulfonate and 1, 2-dihydroxy-1, 2-ethanedi sulfonate in the aqueous phase was carried out. The obtained rate constants can be used for atmospheric modeling.

Three competitive dissociation pathways of glyoxalate

Three possible lower barrier dissociation pathways of the deportonated glyoxylic acid in aqueous solution are predicated by means of B3LYP and CCSD（T） （single-point） methods. The calculated results suggest that the formation of formate ion is the energetically most favorable process, and that the decomposition reaction is occurring through nucleophilic attack of negatively charged carboxylic oxygen on the α-carbon. This is in good agreement with the proposed mechanisms of the mass spectrometry experiment.

Study of the Crosslinking of PVA with Glyoxal in LbL Nanocomposites

Crosslinking is a common practice to improve the barrier properties of polymers. In this study, Montmorillonite (MMT) was used with Polyvinyl alcohol (PVA) to deposit nanocomposite coatings which were crosslinked with glyoxal (Gly) by Layer by Layer (LbL) on a PET substrate. Two crosslinking conditions were studied, under mild condition and with an acidic environment. Mild condition was useful to identify the reversibility steps and the optimum crosslinking times while the acidic environment was essential to investigate the crosslinking mechanism, by determining the permeability for different crosslinking times. PVA and PVA-MMT coatings showed a strong correlation between the permeability coefficients for different crosslinking times and the FTIR results.

Overview of the Synthesis, Characterization, and Application of Tannin-Glyoxal Adhesive for Wood-Based Composites

More than a century after its initial synthesis,urea-formaldehyde(UF)resins still have dominant applications as adhesives,paints,and coatings.However,formaldehyde in this industry produces formaldehyde emissions that are dangerous to health.Scientists have spent the last decade replacing formaldehyde and phenol with environmentally friendly substances such as glyoxal and tannin to create bio-based adhesives.This review covers recent advances in synthesizing glyoxal tannin-based resins,especially those made from sustainable raw material substitutes and changes made to synthetic processes to improve mechanical properties.The efficacy of using tannin-glyoxal adhesives in producing wood-based composites has been proven.The glyoxylate reaction forms cross-linked bridges between the aromatic sites of the tannin and glyoxal molecular structures.Glyoxal tannin adhesive with a greater percentage of glyoxal than tannin will produce an adhesive with better characteristics.The gel time reduces as the hardener concentration rises from 7.5%to 15%when glyoxal is used in adhesives.However,excessive amounts of glyoxal will result in a decrease in viscosity values.Glyoxal exhibits faster delivery degradation when it reaches a maximum temperature of approximately 130°C,although it initiates the curing process slightly slower at 110°C.Adding glyoxal to tannin-based adhesives can improve the mechanical properties of composite boards.The wet shear strength of the resulting plywood is increased by 105.4%with the addition of 5-weight percent tannin-based resin with glyoxal as a cross-linker in Soy Protein Adhesive.With glyoxal as a hardener,the panels produced showed good internal bond strengths(>0.35 MPa)and met the international standard specifications for interior-grade panels.

Robust magnetic laccase-mimicking nanozyme for oxidizing o-phenylenediamine and removing phenolic pollutants

In this study, we report a novel magnetic biomimetic nanozyme(Fe3O4@Cu/GMP(guanosine5′-monophosphate)) with high laccase-like activity, which could oxidize toxic ophenylenediamine(OPD) and remove phenolic compounds.The magnetic laccase-like nanozyme was readily obtained via complexed Cu2+and GMP that grew on the surface of magnetic Fe3O4 nanoparticles.The prepared Fe3O4@Cu/GMP catalyst could be magnetically recycled for at least five cycles while still retaining above 70% activity.As a laccase mimic,Fe3O4@Cu/GMP had more activity and robust stability than natural laccase for the oxidization of OPD.Fe3O4@Cu/GMP retained about 90% residual activity at 90℃ and showed little change at pH 3–9, and the nanozyme kept its excellent activity after long-term storage.Meanwhile, Fe3O4@Cu/GMP had better activity for removing phenolic compounds, and the removal of naphthol was more than 95%.Consequently, the proposed Fe3O4@Cu/GMP nanozyme shows potential for use as a robust catalyst for applications in environmental remediation.

VO(acac)_2 catalyzed condensation of o-phenylenediamine with aromatic carboxylic acids/aldehydes under microwave radiation affording benzimidazoles

Vanadyl acetylacetonate,VO（acac）_2,has been found to be very effective catalyst for synthesis of a variety of benzimidazoles under solvent-free condition.The methodology involves the exposure of a mixture of o-phenylenediamine and a selected aromatic carboxylic acid/aldehyde to microwave radiation without the use of any solvent or supporting agents.The benzimidazoles were obtained in quick time with high yields.

Imine-Rich Poly(o-phenylenediamine) as High-Capacity Trifunctional Organic Electrode for Alkali-Ion Batteries

Alkali-ion batteries,including potassium-ion batter-ies,lithium-ion batteries,and sodium-ion batteries are important energy storage devices;however,with the cation size increased,there exists a great challenge for an inorganic electrode material to accommodate the different properties of the alkali-ion.Herein,as a proof-of-concept experiment,an imine-rich poly(o-phenylenediamine)(PoPD)is syn-thesized through a rational controllable oxidization.Due to the abundance of active sites and ladder-conjugated structure,PoPD in the optimized oxida-tion state endows alkali-ion batteries with a stable cyclability at high capacity.The highly reversible redox performance of PoPD with alkali-ions is verified by theoretical calculations and demonstrat-ed as a trifunctional electrode material(537 and 307 mAh·g^(−1) for Li and Na storage capacity after 300 cycles,respectively),especially for successful application in potassium storage(450 mAh·g^(−1) after 205 cycles),and provides compelling evidence for the wide application of organic electrode materials.

In（OTf）3-Catalyzed Synthesis of Functionalized 1,5-Benzodiazepines from o-Phenylenediamine and Alkyl Propiolates under Solvent-Free Reaction Conditions

A simple, environmental-friendly, and practical method for the synthesis of benzodiazepine derivatives through a reaction of substituted o-phenylenediamines with alkyl propiolates has been developed. The reactions generated the 1,5-benzodiazepines in good to excellent yields in the presence of catalytic amount of In（OTf）3 under sol- vent-free reaction conditions.

温度和湿度对乙二醛聚合物加固饱水梓木文物性能和微观结构的影响

乙二醛聚合物加固饱水梓木文物在自然环境或者博物馆存放时,受环境因素如温度和湿度的影响会导致文物发生劣化。本研究采用傅里叶红外光谱(FTIR)、扫描电镜(SEM)等方法研究了乙二醛聚合物脱水加固饱水梓木试样在不同温度和湿度环境中性能与微观结构变化。结果显示,饱水梓木文物材料经乙二醛聚合物脱水加固后,乙二醛聚合物与梓木细胞壁结合紧密,部分填充于梓木细胞内加固梓木细胞壁。试样在25℃和50%RH环境中试验30 d其结构和性能无明显变化。在60℃和50%RH环境中试验30 d,试样内部的乙二醛聚合物逐渐均匀附着于细胞壁且表面平滑,试样横截面断口平整;但试样表面的乙二醛聚合物逐渐消失,暴露出木材本体。在25℃和95%RH环境中乙二醛聚合物吸湿性明显增强,其与水的结合能力高于梓木细胞壁,乙二醛聚合物与细胞壁之间的结合被破坏,失去加固效果,但仍填充于细胞中。最后分析了温湿度对乙二醛聚合物加固饱水梓木性能与结构的影响机制,并提出了试样在吸湿和脱水过程中乙二醛聚合物与梓木细胞壁的结构变化模型。

异氰酸酯增强尿素-乙二醛树脂的结构与性能研究

为提升尿素-乙二醛树脂(UG)的耐水性能,本研究在UG树脂中添加高活性的异氰酸酯(MDI)共混制备了异氰酸酯/尿素-乙二醛(MDI-UG)木材胶黏剂。采用傅里叶变换红外光谱(FT-IR)、核磁共振波谱仪(NMR)和X射线光电子能谱(XPS)对其固化结构进行表征,通过差式扫描量热分析(DSC)、动态热机械分析(DMA)和扫描电镜(SEM)对其固化性能进行分析,以MDI-UG混合体系制备胶合板并测定其力学性能。结果表明UG树脂中含有的活泼氢基团与异氰酸酯反应形成新的氨基甲酸酯;与UG树脂相比,MDI-UG树脂的固化温度降低且热稳定性提高;采用扫描电镜下可观测到MDI-UG树脂的固化颗粒更加密集且交联支化程度明显提高;当MDI的添加量为3%且乙二醛与尿素的摩尔比为1.3:1时,所制得胶合板的热水湿状剪切强度达到0.72 MPa,表明MDI的引入显著改善了UG树脂的耐水性,而且充分发挥了UG树脂优异的环保性能和异氰酸酯的高强度特点。