Kinetic and mechanism of reactions of L-α-Glutamic acid and L-Glutamine with pyridoxal

The kinetics and mechanisms of condensation of pyridoxal with L-α-glutamic acid and L-glutamine were studied by UV spectroscopy and polarimetry. L-α-Glutamic acid reacts with pyridoxal to form a Schiff base whose subsequent hydrolysis gives rise to pyridoxamine and α-ketoglutaric acid. The reaction of Lglutamine with pyridoxal involves the Γ-NH₂ group and affords a Schiff base whose subsequent hydrolysis gives rise to pyridoxamine and L-α-glutamic acid.     

Synthesis and Properties of Aryloxy-terminated Polydimethylsiloxanes

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Synthesis and anti-α-glucosidase activity evaluation of betulinic acid derivatives

In this article, a series of betulinic acid derivatives (3a ～ 3u, 4a ～ 4e) were synthesized through a stepwise structure optimization and evaluated for their anti-α-glucosidase activities. All synthesized derivatives exhibited stronger anti-α-glucosidase activities (IC₅₀: 0.56 ± 0.05 ～ 3.99 ± 0.23 μM) than betulinic acid (IC₅₀: 7.21 ± 0.58 μM) and acarbose (IC₅₀: 611.45 ± 15.51 μM). Compound 3q presented the outstanding inhibitory activity (IC₅₀: 0.56 ± 0.05 μM), which was ～ 1100 time stronger than that of acarbose. Compound 3q was revealed as a reversible and noncompetitive α-glucosidase inhibitor by inhibitory mechanism assay. Fluorescence spectra, 3D fluorescence and CD spectra results showed that the interaction of compound 3q with α-glucosidase caused the conformational and secondary structure content change of α-glucosidase. Finally, the molecular docking simulated the interaction between compound 3q with α-glucosidase and the physicochemical parameter was assessed using SwissADME software.     

Synthesis and Properties of IPN Hydrogels Based on Konjac Glucomannan and Poly（acrylic acid）

As a random copolymer of β-(1,4) linked D-mannose and D-glucose, konjac gluco- mannan (KGM) is a naturally occurring water-soluble polysaccharide, and has been paid attention in the field of drug controlled release carriers potentially used in colon1,2. …     

Synthesis and Properties of Polyetherketones Containing Sulfide and Phthalazinone

High molecular weight copoly(ether ketone)s (PEK) based on 4-(4-hydroxyphenyl)-1-phthalazinone (DHPZ)/4,4′-thiobisphenol (TBP)/4,4′-diflourodiphenylketone (DFK) were prepared by nucleophilic substitution polycondensation. The copolymers were characterized by FT- and ^1H-NMR. Thermal properties and solubility of copolymers were studied.     

Hydrothermal Synthesis, Crystal Structure and Electrochemical Properties of Complex Cu(α-Furacrylic acid)2(phen)

The title complex (C26H18CuN2O6, Mr=517.96) has been synthesized by the reaction of α-furanacrylic acid with 1,10-phenanthroline (phen) in the solvent mixture of water and methanol. Crystal data: monoclinic, space group C2/c with a=2.2927(4), b=1.01248(18), c=1.05061(18) nm, β=111.188(3)°, V=2.274(7) nm3, Dc=1.513 g/cm3, Z=4, F(000)=1060,μ=1.007mm-1, R=0.0320 and wR=0.0781. The crystal structural analysis shows that the copper atom is coordinated with four oxygen atoms from two α-furacrylic acids and two nitrogen atoms from 1,10-phenanthroline, giving a distorted octahedral coordination geometry. The result of electrochemical analysis shows that the electron transfer in the electrode reaction is quasi-reversible.     

Hydrothermal Synthesis, Crystal Structure and Electrochemical Properties of Complex Cu（α-Furacrylic acid）2（phen）

The title complex (C26H18CuN2O6,Mr=517.96) has been synthesized by the reac-tion of α-furanacrylic acid with 1,10-phenanthroline (phen) in the solvent mixture of water and methanol. Crystal data: monoclinic,space group C2/c with a =2.2927(4),b=1.01248(18),c=1.05061(18) nm,β=111.188(3)o,V=2.274(7) nm3,Dc=1.513 g/cm3,Z=4,F(000)=1060,μ= 1.007mm?1,R=0.0320 and wR=0.0781. The crystal structural analysis shows that the copper atom is coordinated with four oxygen atoms from two α-furacrylic acids and two nitrogen atoms from 1,10-phenanthroline,giving a distorted octahedral coordination geometry. The result of electroche-mical analysis shows that the electron transfer in the electrode reaction is quasi-reversible.     

Synthesis and Luminescence Properties of Barium Fluorotungstate Phosphors

TheluminescenceandenergytransferoftUngstatesarewellknownforalongtimeandwasreviewedbyBlassell].ButbariumtUngstateshowonlyweakluminescenceevendowntoliquidheliumtemperatureI'1.WeweresurprisedtofmdthatBa2Wo3F4isanefficientphosphorwhichcanbepracticallyused.lnthispaper,thepreparationmethodandluminescencepropertiesofBa2Wo3F4phosphorwereinvestigated.TherelationshipbetWeentheluminescentpropertiesandcrystaIstTUctUrewasdiscussed.=EXPERIMENTALThesampleswerepreparedbysolidstatereactionfrommixtur…     

Synthesis and Properties of A Novel Triphenylamine Derivative

A novel triphenylamine derivative of 4, 4‘-bis-[2-[4-[N,N-bis-(4-methoxyphenyl-amino)] phenyl-l-yl]-viny1-1-y1]-1, 1‘-biphenyl (DMPAVBI) was synthesized. The chemical structure was confirmed by IR, ^1H NMR spectroscopy and elemental analysis. Its properties were studied by UV-Vis spectroscopy, photoluminescence spectroscopy and cyclic voltammetry methods.     

Synthesis and Two-photon Absorption Properties of s-Triazine Derivatives

Two new s-triazine derivatives, which belong to linear dipolar type and triangle octupolar type respectively, have been synthesized. The structure of the dipolar compound has been determined by X-ray diffraction. The two-photon absorption cross-section σ, and the two-photon excited fluorescence (TPEF) intensities are increased significantly from dipolar compound to octupolar compound.     

Synthesis and Antioxidant Properties of Novel Silybin Analogues

Eight novel silybin analogues (7a-h) were synthesized and their antioxidant properties including the capability of scavenging superoxide anion free radicals and the inhibitory effect on DPPH free radicals were determined. Several synthetic compounds showed comparable antioxidative effect to that of quercetin.     

α-Substituted Silyl and Phosphonyl Phosphonates. An Extensive Study of their Synthesis and Properties

Abstract

Phosphoryl and silyl chlorides phosphonoalkylation lead to the direct generation of phosphonyl-phosphonyl and phosphonyl-silyl carbanions the properties of which are discussed.     

Synthesis and Acid-Base Properties of α-Aminophosphoryl Compounds

-Aminophosphoryl compounds of the phosphonate, phosphine oxide, and ,-bis(phosphine oxide) series and some of their thiophosphoryl analogs were synthesized. Potentiometric measurements of the pK_a of the conjugate acids revealed an insignificant effect of variation of substituents on the phosphorus, nitrogen, and -carbon atoms on the basicity of the phosphorylated amines. The latter are weak bases. Organophosphorus groups decrease the basicity of the amines by almost 5 pK _a units. The role of the hydrophobic effect and intramolecular H-bonding in the obtained substances was discussed.     

Synthesis and Properties of Aryloxy—terminated Polydimethylsiloxanes

Aryloxy-terminated polydimethylsiloxanes (AOS) were synthesized by the telomerization of hexamethylcyclotrisiloxane(D3) with phenols.The structures of AOS were characterized by UV,IR,^2HNMR and elemental analysis,The effects of the reaction conditions and the mole ratios of the reactants on the molecular weight of the polymer were discussed.AOS′s structural influence on bactericidal action,flocculation and hydrolysis was studied.     

Synthesis and Properties of a Novel Photochromic Compound

A new photochromic compound containing pyrazolone-ring was synthesized, and its crystal structure was determined on X-ray singlecrystal diffraction, which belongs to monoclinic crystal system, space group P21/c. The UV spectrum of the compound is studied.     

A Regio- and Stereo-Selective Synthesis of a Monoter-Pene-α-Methylene-γ-Butyrolactone

In our synthetic work on the transformation of simple p-menthane monoterpenes, readily available from Brazilian essential oils, into biologically active sesquiterpene lactones, we have prepared the model lactone 4 from p-menth-8-ene 1.¹ The key step in this sequence is a lead tetra-acetate (LTA) oxidative cyclisation² of the 1,3 diol 2 into the tetrahydrofuran 3. The final product is the cis fused lactone 4, isolated as two epimers about the methyl group.     

Synthesis and Properties of Phosphorylated and Silylated α-Mercaptocarbonyl Compounds

Abstract

Phosphorylation and silylation of α -mercaptooarbonyl compounds have been investigated. A novel type of 1.4 S-O migration trimethylsilyl and P(III) groups has been discovered. The thiophosphite-thiophosphonate rearrangement when exposed to oxygen as well as heterocyclization with the formation of 1,3,2-oxathiaphospholenes and 1,3,2-oxathiasilalenes were also found. Some regularities of these processes and the properties of heterocycles synthesized have also been brought out.     

Synthesis and Novel Properties of Alkyl Thiophosphoramidate Derivatives of Nucleosides

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Synthesis and Novel Properties of Alkyl Thiphosporamidate Derivatives of Nucleosides

Novel alkyl thiophosphoramidate derivatives of nucleosde analogues(5) have been prepared by phosphochloridothioate chemistry.O-Isopropyl 2‘,3‘-O-isopropylidene uridine-5‘-yl N-thiophosphoryl threonine and serine methyl esters(5a and 5b )underwent the intramolecular catalyzed hydrolysis reaction.