金纳米粒子表面能量转移法测定水中的铅离子

荧光素修饰的凝血酶适配体(5’-FAM-GGT TGG TGT GGT TGG-3’)可与Pb2+选择性地形成G-四链体,这一构象变化能改变作为能量供体的荧光染料和作为能量受体的金纳米粒子之间的距离,使体系的荧光强度与Pb2+浓度具有一定的相关性,从而建立了一种基于纳米材料表面能量转移灵敏检测水溶液中Pb2+的分析方法。研究表明,在Pb2+浓度为12.5~100 nmol/L范围内,荧光恢复效率(F/F0)与Pb2+浓度间呈良好的线性关系,线性回归方程为y=0.910+0.007c(R2=0.997),检出限为10 nmol/L。用本方法检测自来水中Pb2+,结果令人满意。     

Structure,Antibacterial Activity and Theoretical Study of the Forming Mechanism of Compound [(5-Methyl-3-oxo-2-phenyl-1H-pyrazol-4-yl)-thiophen-2-yl-methylene] Thiosemicarbazide

A new thiosemicarbazone compound derived from 1-phenyl-3-methyl-4-(2-thenoyl) pyrazolone-5(HPMTP) and thiosemicarbazide has been synthesized and characterized by IR, HNMR, MS, elemental analysis, UV and single-crystal X-ray diffraction. The compound crystallizes in monoclinic system, Cc space group with a = 7.5925(8), b = 20.263(2), c = 11.4669(13) ,  = 107.825(8)°, V = 1679.5(3) 3, Z = 4, R = 0.0316 and wR = 0.0687. The results of antibacterial activity test against Escherichia coli and Bacillus subtilis indicate that the compound possesses the same antibacterial activity as the contrast(Norfloxacin). Theoretical study of the forming mechanism to the title compound at the RHF/6-31G(d) level shows that there are two steps. The distal amino group of thiosemicarbazide is added to the 4-carbonyl group of HPMTP which forms TM. Then a dehydration reaction occurs in TM and generates a stable product PC.     

Synthesis,Crystal Structure and Anticoagulant Activity of 5-Chloro-N-[[（5S）-2-oxo-3-[4-（2- oxopyridin-1 （2H）-yl）phenyl] oxazolidin-5- yl] methyl] thiophene-2-carboxamide①

The title compound(zifaxaban 2, C20H16ClN3O4 S, Mr = 429.87) was synthesized and its crystal structure was determined by single-crystal X-ray diffraction. Zifaxaban crystallizes in monoclinic, space group P21 with a = 5.7900(12), b = 13.086(3), c = 12.889(3) A, β = 100.86(3)°, V = 959.1(3) A3, Z = 2, Dc = 1.489 g/cm3, F(000) = 444, μ = 0.342 mm-1, the final R = 0.0320 and wR = 0.0640 for 2717 observed reflections(I 2σ(I)). The absolute configuration of the stereogenic center in the title compound was confirmed to be S by single-crystal X-ray diffraction. Four existing intermolecular hydrogen bonds help to stabilize the lattice and the molecule in the lattice to adopt an L-shape conformation. Zifaxaban was slightly more active than rivaroxaban 1 in in vitro assay against human FXa and therefore is promising as a drug candidate.     

Parity Alternation of Silicon-doped Ternary Cationic Clusters HC_nSi_2~+(n=1～9)

Systematic study on the electronic/geometrical structures and the parity alternation effect of silicon-doped ternary cationic clusters HCnSi2＋（n = 1 ~9） have been carried out at the coupled cluster level. The ground-state （G-S） isomers of the clusters have been defined. The C, chains of the G-S isomers display polyacetylene-like structures. The even-n cations are more stable than the odd-n ones. Such a trend of even/odd alternation has been elaborated based on concepts of the bond character, atomic charge, incremental binding energy, ionization potential, proton affinity and fragmentation energies of the systems. The findings accord with the relative intensities of HC,,Si2＋ species recorded in the related mass spectrometric experiments.     

Syntheses,Crystal Structures and Antibacterial Activities of Two Heterocyclic Schiff Base Compounds

Two heterocyclic Schiff bases were synthesized via the condensation reactions of primary amines with carbonyl compounds. 2-[(4-pyridylmethylene)-amino] phenol(compound 1) was synthesized by the interaction of 4-pyridinecarboxaldehyde with o-aminophenol in ethanol solvent; N,N‘-bis(3-(furan-2-yl)allylidene)benzene-1,4-diamin(compound 2) was synthesized by the interaction of 3-(2-furyl)acrolein with p-phenylenediamine in ethanol medium. The compounds were characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction. Compound 1(C12H10N2O) crystallizes in the monoclinic system, space group P21/c with a = 7.0771(7), b = 7.2820(7), c = 19.849(2),β= 96.3390(10)°, V = 1016.66(17) ?3, Z = 4, Mr = 198.22, Dc = 1.295 g/cm3, F(000) = 416, GOOF = 1.060, μ= 0.085 mm-1, the final R = 0.0371 and wR = 0.0929 for 1497 observed reflections with I 2σ(I). Compound 2(C20H16N2O2) crystallizes in the orthorhombic system, space group Fdd2 with a = 26.344(15), b = 48.50(3), c = 5.293(3), V = 6764(7) ?3, Z = 16, Mr = 316.35, Dc = 1.243 g/cm3, F(000) = 2656, GOOF = 1.043, = 0.081 mm-1, the final R = 0.0526 and wR = 0.1267 for 2059 observed reflections with I 2σ(I). 1 and 2 molecules are connected through hydrogen bonds to generate a 2D network and a 1D chain structure, respectively. The preliminary antibacterial activity results showed that the title compounds display excellent antibacterial activities to Escherichia coli, Staphylococcus aureus and Bacillus subtilis.     

Syntheses,Crystal Structures,and Biological Activities of Two 5-Pyrimidinyl-1,2,4-oxadiazoles

Two 5-pyrimidinyl-1,2,4-oxadiazoles were synthesized through two different routes and their structures were characterized by single-crystal X-ray diffraction, NMR and MS. Compound 3, 5-(2-chloro-4-methyl-6-phenylpyrimidin-5-yl)-3-phenyl-1,2,4-oxadiazole, crystallizes in orthorhombic, space group Pbca with a = 19.1575(11), b = 8.2115(5), c = 21.2035(12), V = 3335.6(3)3 and Z = 4. Compound 6, 5-(2,6-dichloropyrimidin-4-yl)-3-phenyl-1,2,4-oxadiazole, crystallizes in monoclinic space group Pn with a = 8.4275(13), b = 5.4088(8), c = 13.493(2), β = 99.768(3)o, V = 4658.6(6)3 and Z = 8. Preliminary bioassay indicated that the two title compounds had good herbicidal activities.     

A New Tetranuclear Cobalt Cluster with （1H-Benzimidazol-2-yl）-methanol Synthesis and Crystal Structure

A new tetranuclear cluster [Co4(bm)6Cl2]·(H2O)2·(CH3OH)(1, Hbm is(1H-benzimidazol-2-yl)-methanol) has been synthesized by solvothermal method and structurally determined by IR, elemental analysis, and single-crystal X-ray diffraction. Complex 1 belongs to monoclinic space group P21/n with a = 21.1713(5), b = 12.7948(3), c = 24.0195(9) , β = 95.309(3)°, V = 6478.6(3) 3, Z = 4, F(000) = 2568, Dc = 1.289 g·cm–3, Mr = 1257.63, μ = 9.096 mm–1, S = 1.000, the final R = 0.0861 and wR = 0.2552 for 4956 observed reflections with I 2σ(I). Two connected face-sharing cubes are observed in the framework of 1, each with one vertex missing. Complex 1 forms a 2-D network through N–H···O hydrogen bonds. The apparent holes can be observed.     

Synthesis and Characterization of Two Binuclear Macrocyclic Zinc(Ⅱ) Complexes by Anion Exchange

Two macrocyclic zinc(II) complexes {[ZnL(VO3)2]·0.33H2O}n(1) and [ZnL(H2O)2][Ni(CN)4](2)(L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) have been obtained from the reactions of [ZnL](ClO4)2 with NH4VO3 and K2[Ni(CN)4], respectively, and structurally characterized by elemental analysis, IR, XRPD, TG and X-ray diffraction. Single-crystal X-ray diffraction analyses indicated that the Zn(II) atom lies on an inversion center and is octahedrally coordinated by four nitrogen atoms of the tetradentate macrocyclic ligand in the equatorial plane and two oxygen atoms of [VO4] tetrahedra in the axial positions in 1, and two oxygen atoms of two water molecules in 2. Complex 1 shows a three-dimensional structure, which is constructed by the links of [VO3]nn- chains with [ZnL]2+, forming one-dimensional channels occupied by guest water molecules. The monomers of [ZnL(H2O)2]2+ and [Ni(CN)4]2- are connected through the intermolecular hydrogen bonds to form a two-dimensional sheet in complex 2.     

The Relationship of Freeze Tolerance with Intracellular Compounds in Baker’s Yeasts

Freeze-tolerant baker’s yeasts are required for the processing of frozen doughs. The present study was carried out to investigate the cell survival rate after frozen storage and the change of fermentability in dough due to frozen storage, and to discuss quantitatively the relationship of freeze tolerance with intracellular trehalose, amino acids, and glycerol, using six types of baker’s yeasts as the test materials. The experimental results showed that the fermentability of yeast cells in frozen dough was strongly correlated with the cell survival rate. The baker’s yeast with a higher level of cell survival rate had a larger increase in the total intracellular compound content after frozen storage, and the cell survival rate increased linearly with increasing total intracellular compound content in frozen yeast cells. Trehalose was a primary compound affecting freeze tolerance, followed by glutamic acid, arginine, proline, asparagic acid, and glycerol. The basic information provided by the present study is useful for exploring the freeze-tolerance mechanisms of baker’s yeast cells, breeding better freeze-tolerant baker’s yeast strains, and developing more effective cryoprotectants.     

共振散射法测定安乃近含量

在pH=5.0的B-R缓冲溶液中,Fe(Ⅲ)与邻菲啰啉反应生成无色配合物,从而使得体系在374nm波长处产生1个较强的共振散射峰。加入安乃近(或4-甲氨基安替比林)后,其将Fe(Ⅲ)还原成Fe(Ⅱ),而生成一种橙红色配合物,使得体系在374nm(或373nm)波长处的共振散射信号减弱。在最佳实验条件下,当安乃近浓度在0.634~15.2μg/mL范围内,体系的共振散射信号△I与安乃近的浓度之间有较好的线性关系,检出限为5.75ng/mL。该方法可直接用于测定安乃近含量,回收率为100.4%~103.4%。