Regio- and stereoselective hydrogenation of methyl substituted pentadien-1-ols by baker's yeast

(E)-2-methyl- and (E)-3-methyl-2,4-pentadien-1-ols are reduced to (S)-2-methyl- and (S)-3-methyl-4-penten-1-ols, respectively, using baker's yeast as a regio- and stereoselective reagent. This microbiological conversion provides an efficient route to bifunctional and enantiomerically pure C₆-building blocks containing the C' -CH(Me )-C'' grouping.     

Production of L-phenylalanine from acetamidocinnamic acid usingBacillus sphaericus andParacoccus denitrificans

To establish an efficient production method for L-phenylalanine (L-Phe), the possibility of L-Phe production from acetamidocinnamic acid by a two-step enzyme reaction was investigated.Bacillus sphaericus N-7 (FERM-P no. 6746) was selected as an enzyme source for the acylase used to form phenylpyruvic acid from aceta midocinnamic acid.Paracoccus denitrificans IFO 12442 was selected as an aminotransferase source for the conversion of phenylpyruvic acid to L-Phe. By using both cell types, 0.46M L-Phe was produced in a molar yield of 92% from 0.5M acetamidocinnamic acid.     

Probing the stereochemistry of E. coli 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase (phenylalanine-sensitive)-catalyzed synthesis of KDO 8-P analogues

The five-carbon phosphorylated monosaccharide analogues, D-arabinose 5-phosphate, D-ribose 5-phosphate, and 2-deoxy-D-ribose 5-phosphate, were separately condensed with (Z)- and (E)-[3-(2)H]-phosphoenolpyruvate (PEP) in the presence of Escherichia coli 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAH 7-P) synthase (phe) to give in the case of (Z)-[3-(2)H]-PEP (3S)-[3-(2)H]-3-deoxy-D-manno-octulosonate 8-phosphate, (3S)-[3-(2)H]-3-deoxy-D-altro-octulosonate 8-phosphate, and (3S)-[3-(2)H]-3,5-dideoxy-D-altro-octulosonate 8-phosphate, respectively, whereas incubation with (E)-[3-(2)H]-PEP gives the corresponding (3R)-monosaccharides. These results are in complete agreement with the observed facial selectivity of DAH 7-P synthase for its normal substrates D-erythrose 4-phosphate and PEP and provide direct evidence that DAH 7-P synthase (phe) catalyzes the si face addition of the C3 of PEP to the re face of C1 of the phosphorylated monosaccharides tested. Products formed by DAH 7-P synthase (phe)-catalyzed condensation of (Z)- and (E)-[3-F]-PEP with E 4-P were completely characterized by (1)H and (19)F NMR analysis for the first time. Results of our studies suggest that disappearence of the double bond between C2 and C3 of PEP and formation of a bond between C3 of PEP and C1 of the phosphorylated monosaccharide tested occur in concert during the DAH 7-P synthase-catalyzed condensation reaction.     

Reversible molecular switching of ruthenium bis(bipyridyl) groups bonded to oligothiophenes: effect on electrochemical and spectroscopic properties

We report the preparation of complexes in which ruthenium(II) bis(bipyridyl) groups are coordinated to oligothiophenes via a diphenylphosphine linker and a thienyl sulfur (P,S bonding) to give [Ru(bpy)(2)PT(3)-P,S](PF(6))(2) (bpy = 2,2'-bipyridyl, PT(3) = 3'-(diphenylphosphino)-2,2':5',2' '-terthiophene), [Ru(bpy)(2)PMeT(3)-P,S](PF(6))(2) (PMeT(3) = 3'-(diphenylphosphino)-5-methyl-2,2':5',2' '-terthiophene), [Ru(bpy)(2)PMe(2)T(3)-P,S](PF(6))(2) (PMe(2)T(3) = 5,5' '-dimethyl-3'-(diphenylphosphino)-2,2':5',2' '-terthiophene), and [Ru(bpy)(2)PDo(2)T(5)-P,S](PF(6))(2) (PDo(2)T(5) = 3,3' ' '-didodecyl-3' '-diphenylphosphino-2,2':5',2' ':5' ',2' ':5' ',2' ' '-pentathiophene). These complexes react with base, resulting in the complexes [Ru(bpy)(2)PT(3)-P,C]PF(6), [Ru(bpy)(2)PMeT(3)-P,C]PF(6), [Ru(bpy)(2)PMe(2)T(3)-P,C]PF(6), and [Ru(bpy)(2)PDo(2)T(5)-P,C]PF(6), where the thienyl carbon is bonded to ruthenium (P,C bonding). The P,C complexes revert back to the P,S bonding mode by reaction with acid; therefore, metal-thienyl bonding is reversibly switchable. The effect of interaction of the metal groups in the different bonding modes with the thienyl backbone is reflected by changes in alignment of the thienyl rings in the solid-state structures of the complexes, the redox potentials, and the pi --> pi transitions in solution. Methyl substituents attached to the terthiophene groups allow observation of the effect of these substituents on the conformational and electronic properties and aid in assignments of the electrochemical data. The PT(n)() ligands bound in P,S and P,C bonding modes also alter the electrochemical and spectroscopic properties of the ruthenium bis(bipyridyl) group. Both bonding modes result in quenching of the oligothiophene luminescence. Weak, short-lived Ru --> bipyridyl MLCT-based luminescence is observed for [Ru(bpy)(2)PDo(2)T(5)-P,S](PF(6))(2), [Ru(bpy)(2)PT(3)-P,C]PF(6), [Ru(bpy)(2)PMeT(3)-P,C]PF(6), and [Ru(bpy)(2)PMe(2)T(3)-P,C]PF(6), and no emission is observed for the alternate bonding mode of each complex.     

A study of the interaction between polyvinylpyrrolidone and gemini surfactant G12-3-12 by NMR

The interaction between a water-soluble polymer polyvinylpyrrolidone (PVP) and a gemini surfactant N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-propanediyl-diammonium dibromide (G12-3-12) was investigated by means of NMR in a D₂O solution at 298 K. The critical micelle concentration (СMC), critical aggregation concentration (СAC) and adsorption reached the saturated concentration (C2) were confirmed by chemical shift and self-diffusion coefficients, respectively. The results of the relaxation time ratio (T_R = T₂/T₁) of G12-3-12 show that the motion of the ionic head N⁺–CH₃^* proton (G6) is seriously restricted, and thus, it can be proved that the cationic head groups are situated in the hydrophilic layer of the micelle. The size of the mixed-aggregates in the G12-3-12/PVP solution is larger than pure G12-3-12 micelles according to self-diffusion coefficients, indicating that the G12-3-12 and PVP has formed mixed micelles, and ionic heads N⁺–CH₃^* become more tightly packed in the hydrophilic layer of the micelle shell. On the other hand, strong cross peaks, such as G1-P2, G1-P3, and G2-P3, appear in the 2D nuclear Overhauser enhancement spectroscopy (2D NOESY) spectra of the G12-3-12/PVP system, further indicating that the interaction sites are located between the hydrophobic tail of G12-3-12 and PVP ring.     

中心金属或配体刚性调控的α-酮酸酯对硝基烯的不对称共轭加成

通过手性二胺配体与Cu或Ni络合合成了手性金属催化剂,并将其应用于α-酮酸酯对硝基烯的不对称共轭加成反应中,发展了通过改变中心金属或调节配体刚性实现反应对映选择性反转的策略.使用同一手性二胺配体(1S,1'S)-1,1'-联异吲哚啉,与不同的金属前体(Cu(OAc)2·H2O与Ni(OAc)2·4H2O)络合,可以高选择性地得到绝对构型相反的共轭加成产物(ee值高达94%与93%).同样,使用同一金属前体Cu(OAc)2·H2O,与同一手性源出发合成的两种刚性不同的二胺配体络合,也可以在这个反应中实现产物绝对构型的反转(ee值高达94%与94%).     

Asymmetric Ring-Opening of Cyclohexene Oxide with Mercaptan (Thiophenols) Catalyzed by Chiral Schiff Base/Ti(OPr- i ) 4 or (−)-(S)-Binaphthol/Ti(OPr- i ) 4

New chiral Schiff base ligands 1-4 were synthesized starting from (+)-camphor and (+)-1-(4-nitrophenyl)-2-amino-1,3-propanediol, and their application in asymmetric ring-opening of cyclohexene oxide using mercaptan (thiophenols) as nucleophiles was investigated. The aymmetric ring-opening of cylohexene oxide catalyzed respectively by chiral Schiff bases 1-4 /Ti(OPr- i ) 4 and ( m )-(S)-1,1'-binaphthalene-2,2'-diol 5 /Ti(OPr- i ) 4 complex afforded the corresponding chiral g -hydroxysulfides 6-10 in lower to good yield with lower to moderate ee values. Moreover, the using of ( m )-(S)-1,1'-binaphthalene-2,2'-diol as ligand led to better chiral induction effect.     

六核钴羰基簇的P(OC_2H_5)_3取代衍生物的合成、表征与结构

用P(OC_2H_5)_3与母体簇Co_6(μ_6-P)(μ-SCH_2CH_2CH_2S)(μ- PSCH_2CH_2CH_2S)(CO)_(12)进行取代反应得到一个二取代产物Co_6(μ_6-P)(μ- SCH_2CH_2CH_2S)(μ-PSCH_2CH_2CH_2S)(μ-CO)(CO)_9[P(OC_2H_5)_2]_2（I）, 同时还得到了两个一取代产物Co_6(μ_6-P)(μ-SCH_2CH_2CH_2S)(μ- PSCH_2CH_2CH_2S)(CO)_(11)[P(OC_2H_5)_3]（II a和II b,II b是II a的一个同 分异构体,其谱学数据与II a不同）。对合成的三个簇合物进行了元素分析、IR、 ~1H NMR、~(31)P NMR和MS谱学表征,对I做了X射线单晶衍射测定,其晶体属于单 斜晶系,P2_1/n空间群,晶胞参数：a = 1.1170(2) nm,b = 2.3554(5) nm,c = 1.7977(4) nm,β = 99.50(3)°,V = 4.6649(17) nm~3,Z = 4,D_c = 1.763 g/cm~3,F(000) = 2488,μ = 24.64 cm~(-1)。X射线晶体结构分析表明,取代 位置发生在簇合物顶端的两个钴原子上。晶体结构用直接法解出,经用全矩阵最小 二乘法对原子参数进行修正,最后的偏离因子为R_1 = 0.0497,wR_2 = 0.1386。     

Unprecedented eta(1)-P(basal) coordination of P(4)X(3) molecules (X = S, Se). An experimental and theoretical study of the apical vs basal complexation dichotomy

Reaction of [(triphos)Re(CO)(2)(OTf)] (1) [triphos = MeC(CH(2)PPh(2))(3); OTf = OSO(2)CF(3)] with P(4)S(3) and P(4)Se(3) yields pairs of coordination isomers, namely, [(triphos)Re(CO)(2)[eta(1)-P(apical)-P(4)X(3)]](+) (X = S, 2; Se, 5) and [(triphos)Re(CO)(2)[eta(1)-P(basal)-P(4)X(3)]](+) (X = S, 3; Se, 6). The latter represent the first examples of the eta(1)-P(basal) coordination achieved by the P(4)X(3) molecular cage. Further reaction of 2/3 and 5/6 mixtures with 1 affords the dinuclear species [[(triphos)Re(CO)(2)](2)[mu,eta(1:1)-P(apical,)P(basal)-P(4)X(3)]](2+) (X = S, 4; Se, 7) in which the unprecedented M-eta(1)-P(basal)/eta(1)-P(apical)-M' bridging coordination of the P(4)X(3) molecule is accomplished. A theoretical analysis of the bonding properties of the two coordination isomers is also presented. The directionality of apical vs basal phosphorus lone pairs is also discussed in terms of MO arguments.     

Further resolution of alpha-fetoprotein glycoforms by two-dimensional isoelectric focusing and lectin affinity electrophoresis

Human alpha-fetoprotein (AFP) from serum of patients with cirrhosis and hepatocellular carcinoma (HCC) was separated into several bands by IEF and by erythroagglutinating phytohemagglutinin (E-PHA) affinity electrophoresis. These AFP bands were directly compared in 2-D IEF and E-PHA affinity electrophoresis. IEF of serum AFP was run in 1% agarose IEF gel with 3% Pharmalyte 4.5-5.4. After IEF, a part of the gel was stained for AFP and another part of the gel corresponding to the area of separated AFP bands was cut in 1 mm x 39 mm along the focused direction and transferred to a trough in 1% agarose gel with 0.3 mg/mL E(4)-PHA for second-dimensional affinity electrophoresis. Separated 2-D AFP spots were visualized by antibody-affinity blotting and identified by combining the systems of Johnson et al.. (Johnson, P. J., Ho, S., Cheng, P., Chan, A. et al.., Cancer 1995, 75, 1663-1668) for AFP-I-+IV and of Taketa et al.. (Taketa, K., Ichikawa, E., Taga, H., Hirai, H., Electrophoresis 1985, 6, 492-497) for AFP-P1-5. AFP-P2, the major AFP glycoform, was composed of AFP-I, AFP+I, and AFP+II; AFP-P3, a nonspecific monosialo-AFP, was composed of AFP+II; AFP-P4, HCC-specific monosialo-AFP, was composed of AFP+II, AFP+III, and AFP+IV; and malignancy-related AFP-P5 was composed of AFP+I and AFP+II. Monosialo-AFP (AFP+II) was recovered in all the glycoforms of AFP-P2, -P3, -P4, and -P5; thus, AFP-P4 is more specific to HCC than monosialylated AFP+II.     

Nanoparticle directed domain orientation in thin films of asymmetric block copolymers

We investigated the thin film morphology of two different asymmetric block copolymers (BCP), polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and poly(n-pentyl methacrylate)-block-poly(methyl methacrylate) (PPMA-b-PMMA), loaded with pre-synthesized iron oxide nanoparticles (NP). The chemical composition of the BCP constituents determines the strength of the interaction between polymer chains and nanoparticles. In the case of NP/PS-b-P4VP system, the nanoparticles interact preferentially with the P4VP block and hence localize selectively in the P4VP cylindrical microdomains. However, for the NP/PPMA-b-PMMA system, the nanoparticles have no significant preference for the copolymer blocks and segregate at the polymer/substrate interface. Interestingly, this changes the effective substrate surface energy and hence leads to a remarkable change in domain orientation from parallel to perpendicular with respect to the substrate. These results clearly demonstrate the importance of both enthalpic and entropic factors which determine spatial distribution of NP in BCP films and influence domain orientation.     

Comparison between the effects of TiO2 synthesized by photoassisted and conventional sol-gel methods on the photochromism of WO3 colloids

WO3 colloids can exhibit a blue color under UV-light irradiation due to the absorption of electrons trapped at the energy levels within the forbidden gap and this coloration performance can be improved by TiO2 nanoparticles. In this work, it is found that TiO2 prepared by the photoassisted method (TiO2-P) exhibits stronger enhancement effects than that prepared by the conventional sol-gel method (TiO2-C). Several possible mechanisms have been proposed to account for this phenomenon. The migration of charge carriers toward different directions is promoted since the flat-band potential of TiO2-P colloids is more negative than that of TiO2-C and the contact between WO3 and TiO2 particles is improved in the WO3/TiO2-P system; there are more efficient TiO2 and hole scavengers (i.e., Ti3+ and/or TiO2-O2*- species) in the system containing TiO2-P; the bandgap of TiO2-P becomes narrowed, and so on. In addition, the potential applications of this process are also discussed briefly.     

Enzymatic Synthesis of α-Glucose-1-phosphate: A Study Employing a New α-1,4 Glucan Phosphorylase from Corynebacterium callunae 1

Abstract

In synthetic pathways to complex carbohydrates such as oligosaccharides or nucleotide sugars the activated sugar 1-phosphates serve as important starting molecules. In this study the enzymatic synthesis of α-glucose-1-phosphate (Glc-1-P) has been investigated using a new bacterial α-glucan phosphorylase from Corynebacterium callunae. The major factors governing the rate of reaction and the attainable degree of substrate conversion have been identified and, accordingly, for optimizing the yield and limiting reaction time for the enzymatic process several points must be considered: (i) the pH-dependent equilibrium of reaction, (ii) product inhibition of the phosphorylase and (iii) enzymatic cleavage of α-1,6 glycosidic linkages present in α-1,4-glucans such as starch or maltodextrins by pullulanases to improve their phosphorolytic conversion. Results obtained in continuous experiments with the phosphorylase retained in an ultrafiltration membrane reactor confirmed the complete operational stability of the enzyme for several days at 30 °C. Since no more than approximately 18 % of the inorganic phosphate can be converted into Glc-1-P an efficient procedure for phosphate and product recovery will be particularly important.     

超高效液相色谱-串联质谱法测定动物源性食品中10种水杨酰胺类化合物

建立了动物源性食品中10种水杨酰胺类化合物(5-氯水杨酰苯胺、4'-溴水杨酰苯胺、3',4'-二氯水杨酰苯胺、4',5-二氯水杨酰苯胺、3',4',5-三氯水杨酰苯胺、5-溴-4'-氯水杨酰苯胺、3,5-二溴水杨酰苯胺、4',5-二溴水杨酰苯胺、3,4',5-三溴水杨酰苯胺、3,3',4',5-四氯水杨酰苯胺)的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法。样品经乙腈萃取,氨基固相萃取小柱(SPE)净化,T3色谱柱分离后,以甲醇-0.1%甲酸溶液梯度洗脱,串联质谱电喷雾负模式扫描,多反应监测模式检测,外标法定量。结果表明,10种目标物在一定范围内线性关系良好,相关系数(r~2)不小于0.995 7,检出限为0.5~1.0μg/kg,定量下限为1.5~3.0μg/kg;加标水平为1.5~30.0μg/kg时,回收率为81.0%~106%,相对标准偏差(RSD,n=6)不大于7.5%。该方法净化效果好、定量准确、灵敏快速,适用于动物源性食品中10种水杨酰胺类化合物的检测与确证。     

pH-responsive pseudorotaxane between comblike PEO-grafted triblock polymer and α-cyclodextrin

The pH-responsive inclusion complexation of comblike triblock polymer, P2VP-b-PPEOMA-b-P2VP, with α-cyclodextrin (α-CD) was studied. The triblock polymer was prepared by reversible addition–fragmentation chain transfer polymerization (RAFT) and formed inclusion complexes (ICs) after selective threading of the PEO segment of the triblock polymer through the cavities of α-CD units. For comparison, PPEOMA homopolymer was prepared, and the inclusion complexation with α-CD was also studied. The formed ICs were characterized by XRD and ¹H NMR. The results revealed that P2VP-b-PPEOMA-b-P2VP can form ICs with α-CD even when forming micelles, and the introduction of P2VP had a great influence on the solution property and the stoichiometry of EO to CD of the inclusion complexes depending on the concentration and the pH of the solution.     

Heteropolytopic phosphanylarylthiolato ligands: formation of cis isomers of nickel(II), palladium(III) and platinum(III) complexes with 1-P(Biph)-2-SHC6H4 (Biph = 1,1'-biphenyl-2,2'-diyl)

Reaction of the ditopic phosphanylarylthiol 1-P(Biph)-2-SHC(6)H(4) (BiphPSH, Biph = 1,1'-biphenyl-2,2'-diyl), prepared by lithiation-electrophilic substitution, with NiCl(2)·6H(2)O, Na(2)[PdCl(4)] and [PtI(2)(cod)] (cod = 1,5-cyclooctadiene) in a 2:1 ratio and in the presence of NEt(3) led to formation of exclusively cis isomers of the square-planar complexes cis-[M{(1-P(Biph)-2-S-C(6)H(4))-κ(2)S,P}(2)] ([M{(BiphPS)-κ(2)S,P}(2)]; M = Ni (1), Pd (2), Pt (3)). Density functional calculations support the assumption that this is probably due to intramolecular π-π interaction of the biphenyl groups, which results in enhanced stability of the cis isomers. Compound 1 is the first example of a structurally characterised mononuclear cis-bis(phosphanylthiolato)nickel(III) complex. Small amounts of the trinuclear complex [{PtI(1-P(Biph)-μ-2-S-C(6)H(4)-κ(2)S,P)}(3)] (4) are also formed besides the mononuclear platinum bis-chelate complex 3.     

Geometry and solvent-polarity dependences of the relaxation dynamics of the singlet excited state of center-to-edge phosphorus(V) porphyrin heterodimers

Para- and meta-isomers of center-to-edge phosphorus(V) porphyrin heterodimers (p- and m-Pm-PCl2) composed of a phosphorus(V) tetraphenylporphyrin (P) and a phosphorus(V) tetrakis(4-methoxyphenyl)porphyrin (Pm) were synthesized to investigate the geometry and solvent-polarity dependences of the relaxation dynamics of the lowest singlet excited state (S1) of the porphyrin dimer. The geometrical difference between m- and p-Pm-PCl2 in solution was confirmed by 1H NMR on the basis of the porphyrin ring current model. By the photoexcitation of the dimers, only the fluorescence from 1Pm*-P was observed in both dimers because of the efficient singlet energy transfer from the higher energy 1P* to the lower energy 1Pm*. However, the 1Pm*-P fluorescence had features that differ from the typical fluorescence from monomeric 1Pm*, especially for the solvent-polarity dependence of the quantum yields. Furthermore, all the fluorescence decay curves of 1Pm*-P were double-exponential. The special fluorescence features of 1Pm*-P are due to the equilibrium between 1Pm*-P and the charge-transfer (CT) excited state of the dimer ((Pm-P)CT). By the excited-state equilibrium, 1Pm*-P is efficiently quenched through (Pm-P)CT in highly polar solvents. The contribution of (Pm-P)CT to the decay process of 1Pm*-P is more remarkable in m-Pm-PCl2 than in p-Pm-PCl2, depending on the interaction between the two porphyrin -systems in the heterodimer.     

Crystal Structure of Ordered White Phosphorus(β-P)

Abstract

The low-temperature form of white phosphorus (β-P, T_trans= -76.4°C) is triclinic, P1. The asymmetric unit contains 3 independent tetrahedral P₄ molecules. Intramolecular angles are 60 ± 0.5° and the P-P distances are d=220.9(5) pm. The structure of β-P is related to that of γ-Pu, the Pu atoms being substituted by P₄.     

Structure Features of 1,3,5-Tris(Diphenylphosphinoxidemethylene)Ben zene in Crystal and Solution on the Base of X-Ray,Dipole Moments and Quantum Chemical Analysis

Abstract

The molecular structure, polarity and conformations in solution of 1,3,5-tris(diphenylphosphinoxidemethy1ene)benzene 1,3,5-[Ph₂P(0)CH₂]₃C₆H₃ have been studied by X-ray, dipole moments and quantum chemistry methods. It have been shown, that in crystal molecule has the conformation in which two diphenylphosphinoxide fragments dispose on one and the same side, but the third - on the other side of central benzene ring plane with torsion angles C_SP2-C_SP2-C_SP3-P 60–80° and C_SP2-C_SP3-P=O about 50–70°. In solution conformational picture is more rich: side by side with the structures realized in crystal, conformations with all three diphenylphosphinoxide fragments disposed on one and the same side of central benzene ring plane with torsion angles C_SP2-C_SP2-C_SP3-P 70-90° and C_SP2-C_SP3-P=O about 70–75° become preferable.     

超高效液相色谱-串联质谱法同时测定聚合物食品包装材料中8种添加剂

建立了同时测定聚合物食品包装材料中8种常用添加剂Irgafos 168、Irganox 1010、Irganox 1076、丁基羟基茴香醚（BHA）、没食子酸丙酯（PG）、没食子酸十二酯（DG）、叔丁基对苯二酚（TBHQ）和苯三唑甲酚（UV-326）的超高效液相色谱-串联质谱方法。试样以二氯甲烷为溶剂进行超声提取;采用Waters BEH-C18柱（50 mm×2.1 mm,1.7 μm）分离,以0.05%甲酸水溶液和甲醇为流动相进行梯度洗脱;采用电喷雾离子源正、负离子切换模式和多反应监测模式进行检测。8种添加剂在相应的质量浓度范围内定量离子的峰面积与质量浓度均呈良好线性关系（相关系数R²均大于0.993）,回收率为63.9%~127.0%,相对标准偏差（RSD,n=6）≤15.8%,检出限（S/N=3）为0.13~5.50 μg/L,定量限（S/N=10）为0.45~17.50 μg/L。该方法简便快捷、灵敏度高,适合食品包装材料中常用添加剂的分析测定。