Comparison of the Contributions of Tetrahydrofurfuryl Alcohol and PEG to α-Chymotrypsin Renaturation with High Performance Hydrophobic Interaction Chromatography

The contributions of tetrahydrofurfuryl alcohol(THFA) and polyethylene glyco(PEG) to the renature efficiency of α-chymotrypsin were investigated and compared with each other,The maximum increments of bioactivity recovery of α-Chy were found to be 25.1% for THFA,10.4% for PEG,respectively.The experimental results indicated that the denaturant solution containing THFA contributed more to the renaturation of α-Chy in high performance hydrophobic interaction chromatography(HPHIC) than that containing PEG,when the concentration of THFA was 3.2%,the bioactivity recovery of α-Chy is the highest.     

Crystal structures of the complexes of rare earth picrates with N, N, N'''', N''''-tetraphenyl-3, 6-dioxaoctanediamide

The complexes of rare earth picrate with N,N,N',N'-tetraphenyl-3,6-dioxaoctanediamide(TDD),Eu(picc(TDD)] 2CH3CN and [ Y(pic)3(TDD)],have been synthesized.The crystal structures reveal that TDD at is as n tetradentate ligand,forming a ring-like coordination structure with its oxygen atoms together with one oxygen atom of the bidentate pterate In the Eu(Ⅲ) complex,the europium ion with a larger ionic radius lies out of the ring,while in the Y(Ⅲ) complex,the yttrium ion with a smaller ionic radius enters the cavity of the ligand.The structures of the complexes are greatly affected by the ionic radii due to participation of the picrates in coordination.     

Mechanism of simultaneously refolding and purification of proteins by hydrophobic interaction chromatographic unit and applications

The hydrophobic amino acid residues of a denatured protein molecule tend to react with the particles of the stationary phase of hydrophobic interaction chromatography (STHIC). These hydrophobic interactions prevent the denatured protein molecules from aggregating with each other. The STHIC can provide high enough energy to a denatured protein molecule to make it dehydration and to refold it into its native or various intermediate states. The outcome not only depends on the specific interactions between amino acids, the structure of STHIC, but also depends on the association between the STHIC and mobile phase. The mechanism of protein refolding and the principle of its quality control by HPHIC were also presented. By appropriate selection of the chromatographic condition, several denatured proteins can be refolded and separated simultaneously in a single chromatographic run. A specially designed unit, with diameter much larger than its length, was designed and employed for both laboratory and preparative     

Synthesis,Crystal Structure and Antitumor Activity of a Na(Ⅰ) Coordination Polymer Based on 2-Propyl-4,5-imidazoledicarboxylic Acid and 1,10-Phenanthroline Ligands

A new Na(I) coordination polymer, [Na2(Hpimdc)(H2 pimdc)(phen)2]n(1), has been synthesized by the reaction of NaOH with 2-propyl-4,5-imidazoledicarboxylic acid(H3 pimdc)and 1,10-phenanthroline(phen). The Na(I) coordination polymer 1 was characterized by single-crystal X-ray diffraction analysis and elemental analysis. In 1, the bridged ligand H3 pimdc adopts two modes(singly deprotonated and doubly deprotonated) to coordinate with the Na(I) ion.The Na(1) ion is six-coordinated with three N atoms from a phen ligand and a H2 pimdc ligand,three O atoms from a Hpimdc ligand and two other different H2 pimdc ligands. The Na(2) ion is also six-coordinated with three N atoms from a phen ligand and a Hpimdc ligand, three O atoms from a H2 pimdc ligand and other two different Hpimdc ligands. Complex 1 exhibits a 1 D chain structure built up by μ-H2 pimdc-and μ-Hpimdc2-ligands. The antitumor activities of complex 1 against human SGC7901, A549 and H08910 cells have been tested.     

Influence of amphiphilic structures on the stability of polyphenols with different hydrophobicity

Autooxidation of five polyphenols representing range of different hydrophobicities(catechin gallate (CG),(-)catechin((-)C),epicatechin(EC),epigallocatechin gallate(EGCG)and epigallocatechin(EGC)) in three different aqueous solutions:molecular solution,micellar solution(Tween-20)and liposomal dispersion(soybean lecithin)was monitored by HPLC.The rate of oxidation of the five polyphenols was higher at pH 4.5 than at pH 3.5.Compared with the control,addition of Tween-20(micellar structure)and lecithin(liposomal structure)significantly decreased the degradation of polyphenols.In the presence of lecithin the autooxidation of all the five polyphenols was slower than in the presence of Tween-20. The effective protection of the colloidal structures was compared with the hydrophobicity of the poly- phenols estimated from the partitioning between octanol and water.The protection from oxidation in the presence of the colloidal structures(micellar or liposomal)increased with increasing partitioning of a polyphenol towards the hydrophobic environment.The protecting effect of the colloidal structures was more effective at pH 4.5 than at pH 3.5.     

Synthesis and Liquid Crystal Behaviors of 2,4-Dioxo-3-pentyl 4-decyloxy Cinnamate Rhodium （I） Complexes

The title complexes have been synthesized by the reaction of [RhCI(CO)2]2 or [RhCI(COD)]2 (COD = 1,5-cyclooctadiene)with the organic ligand 2,4-dioxo-3-pentyl 4-decyloxy cinnamate 2. The complex 3 based on dicarbonylrhodium(I) shows nematic phase, while the complex 4 containing rhodium(I) bound to a COD ligand is a nonmesogen. The relationship between molecular structures and liquid crystal behavior has also been discussed by means of computer-aided molecular modeling.     

Zinc-coordination Polymers Based on a Donor-acceptor Mix-ligand System: Syntheses,Crystal Structures and Photophysical Properties

By employing an electron-rich tricarboxytriphenyl amine as donor ligand and electron-deficient 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine as acceptor ligand to assemble with Zn2+ions,three new coordination polymers were successfully synthesized and characterized systematically.Three compounds with different structures were obtained by regulating the reaction solvent,and the effect of the reaction solvent on the synthesis of crystals was explored.Furthermore,the photophysical properties of the compounds were investigated.     

Trichlorozirconium η~2-Hydrazonides: Synthesis,Characterization and Their Catalytic Behavior toward Ethylene Polymerization

The trichlorozirconium η~2-hydrazonides(R=H, A; R=CH_3, B) were synthesized through the finely controlled stoichiometrical reactions of anhydrous zirconium tetrachloride with the lithium salt of either 1-(furan-2-ylmethylene)-2-phenylhydrazonide or 1-(furan-2-ylethylidene)-2-phenyl hydrazonide in the solvent tetrahydrofuran(THF), respectively. These complexes were highly sensitive to air and moisture due to solely using less bulky ligand of hydrazonides. The molecular structures of the title complexes, determined by means of single crystal X-ray diffraction, were found to be the distorted pentagonal bipyramid geometry around zirconium atom, with three chlorides and the hydrazonato ligand acting as the η~2-coordination mode as well as two incorporated THF molecules. Upon activation with either methylaluminoxane(MAO) or modified methylaluminoxane(MMAO), both complexes A and B exhibited catalytic activities toward ethylene polymerization, producing polyethylenes with ultra-high molecular weights.     

Studies on the Electronic Structures and Spectra of C78（CH2）3

The structures and spectra of 20 possible isomers of C78(CH2)3 have been studied by using AM1,INDO/CIS and DFT methods. The results show that the most stable isomer is 1,2,3,4,5,6-C78(CH2)3 (A) with annulene structures,where three -CH2 groups are added to the 6/6 bonds located at the same hexagon passed by the shortest axis of C78 (C2v). Compared with that of C78 (C2v),the first absorption in the electronic spectrum of C78(CH2)3 (A) is blue-shifted because of its wider LUMO-HOMO energy gap. While the IR frequencies of the C–C bonds on the carbon cage are red-shifted owing to the formation of annulene structures and the extension of the conjugated system. The chemical shifts of the carbon atoms in 13C NMR spectra are moved upfield upon the addition.     

Syntheses,Crystal Structures and DNA-binding Properties of Zn(Ⅱ), Ni(Ⅱ) and Co(Ⅱ) Compounds Containing Thiazole Derivatives

Zn(Ⅱ), Ni(Ⅱ) and Co(Ⅱ) compounds(1～3) based on 2-(2-pyridyl)benzothiazole(bpt) and terephthalic acid(PTA) were synthesized. The crystal structures of [Zn(bpt)(PTA)2](1), [Ni(bpt)(PTA)2](2), and [Co(bpt)(PTA)2](3) have been determined by single-crystal X-ray diffraction analysis, which shows that all the three complexes belong to monoclinic system with space group P21/c. Time-dependent density functional theory(TD-DFT) calculation is performed on a reference structure of compound 3. The excited electrons mainly localized at the π* of ligand 2-(2-pyridyl)benzothiazole, which will be convenient for them to bind with the DNA reacting sites. Fluorescence spectroscopy, ultraviolet(UV) spectroscopy and viscosity were used to characterize the interaction of the compounds with Calf thymus DNA(CT-DNA). The results indicate that compounds 1～3 bind to CT-DNA and have a strong interaction with DNA. The compounds can probably bind to CT-DNA via a non-intercalative mode as concluded by studying the viscosity of a DNA solution in the presence of the compounds. This combination can effectively break DNA, which speculates that these three compounds may interact with the cancer cell DNA in this binding mode, thereby damaging the cancer cells.     

Synthesis,Crystal Structure and Copper Complex of 1,3-Alternate p-tert-Butylthiacalix[4]arene 2-picolyl Schiff Base

A p-tert-butylthiacalix[4]arene-based polydentated ligand with four Schiff base units on 1,3-alternate position at lower rim has been prepared in three steps,which coordinated to copper ion to form a novel dicopper complex.The structures of the polydentated thiacalixarene ligand and copper complex were fully characterized by spectroscopy and X-ray single crystal diffraction method.     

N-乙基-1，10-菲罗啉-2-甲胺镍(Ⅱ)配合物的合成、晶体结构及性质研究(英)

A novel ligand N-ethyl-1,10-phenanthroline-2-methanamine and its Ni(Ⅱ) complex have been synthesized. The crystal structure of the complex has been determined by X-ray diffraction method. The Ni(Ⅱ) is five-coordinated by three nitrogen atoms from the ligand and two Cl^- anions in a distorted trigonal bipyramidal environment: the N(2), Cl(1) and Cl(2) in equatorial plane; the N(1) and N(3) in axial positions. The UV-spectra and IR-spectra of the ligand and its Ni(Ⅱ) complex were recorded and discussed. The thermodynamic properties of the ligand with various bivalent metals were studied by potentiometric titrations and the order of the stability constants is in agreement with the Irving-Williams order in coordination chemistry. CCDC: 221750.     

Theoretical Study of Hydrated Cd~（2＋） Interactions with Guanine

Theoretical study was performed to investigate how the hydration of cadmium ca-tion influences the structure and properties of guanine.The aqueous environment was simulated by both explicit solvent(1-5 water molecules) model and implicit solvent model.For complexes in which Cd2+ attached to the N(7) and O(6) sites of guanine,energy analysis together with the Natural Bonding Orbital(NBO) analysis were performed to elucidate the bonding characteristics in detail.The most stable structures are penta-coordinate complexes without aqua ligand located at the guanine site.Higher number of water ligands corresponds to higher stabilization energies.Average bonding energies of G-Cd increase with the number of water molecules.Bonding energies of water ligands depend on its position in the complexes.The charge distribution of guanine changed with increasing the number of water ligands,which may also influence the base-pairing pattern of guanine.There is positive charge transfer from guanine to aqua ligand as the number of the hydration waters increases.IEFPCM optimization has results comparable to the [CdG(H2O)5]2+ structure 5a.     

Self-assembly of a Mixed-valence Cu(Ⅰ)/Cu(Ⅱ) Coordination Polymer Derived from a Conformationally Flexible Tripodal Phosphoric Trimide Ligand

Reaction of a tripodal ligand, N,N?,N??-tris(3-pyridinyl) phosphoric trimide(TPPA) and CuBr_2·2H_2O result in the assembly of a new polymeric copper coordination polymer, which was characterized by single-crystal diffraction, infrared spectroscopy and elemental analysis. The polymer crystallizes in the triclinic system, space group P1 with a = 9.0964(5), b = 10.2592, c = 10.5822(8) ?, V = 933.01(9) ?~3, Z = 2, C_(30)H_(24)Br_4Cu_3N_(12)O_2P_2, M_r = 985.02, D_c = 1.753 g/cm~3, F(000) = 4072 and μ(MoKα) = 0.746 mm~(-1). The final R and w R are 0.0588 and 0.1329 for 4260 observed reflections with I 2σ(I). Cu(Ⅰ) is tetrahedrally coordinated and Cu(Ⅱ) center adopts square planar coordination geometry. Because of the flexibility of the TPPA ligands, the pyridyl rings rotate though a certain angle and three pyridyl rings on the same TPPA rotate by about 45° with respect to the central P=O groups. TPPA ligand acts as a tridentate ligand and is coordinated with three metal centers with its pyridyl donors to form a 2D-sheet like structure, and it is further connected by N–H···O and N–H···Br, resulting in a 3D network packing. Oxidation states of the metal center have been determined by bond valence sum calculation.     

Thermokinetics of the Formation Reaction of Zinc Histidine Complex

The enthalph change of reaction of zinc chloride with L-α-histidine in the temperature range of 25-50℃ has been determined by a microcalorimeter.On the basis of experimental and calculated results,three thermodynamics parameters (the activation enthalpy,the activation entropy,the activation free energy),the rate constant and three kinetic parameters (the activation energy,the pre-exponential constant and the reaction order) of the reaction,and the standard enthalpy of formation of Zn(His)^2 (aq.) are obtained.The results showed that the title reaction easily took place at the studied temperature.     

TD-DFT Study on the Electronic Spectrum Properties of 2,7′-(Ethylene)-bis-8-hydroxyquinoline and Its Derivatives

The structures of 2,7′-(ethylene)-bis-8-hydroxyquinoline and its derivatives were optimized at the ground states using ab initio HF and B3LYP methods. At the same time, the molecular structures of the first singlet excited state for 2,7′-(ethylene)-bis-8-hydroxyquinoline and its derivatives were optimized by CIS/6-31G(d). The absorption and emission spectra based on the above structures were obtained by the time-dependent density functional theory (TD-DFT) by the B3LYP method with the 6-31G(d) basis set. The calculated results of luminescence originate from the electronic transition from the hydroxphenol ring of 8-hydroxyquinoline A to the pyridine ring of 8-hydroxyquinoline B. Their luminescence wave bands can be tuned by different substituents on the ligand of 8-hydroxyquinoline.     

STUDIES ON CRYSTAL AND MOLECULAR STRUCTURES OF DEMETHYLCANTHARATE-M (M=Zn, Cu, Ni, Co)

The complexes of demethylcantharic acid coordinating with Zn~(2+), Cu~(2+), Ni~(2+) and Co~(2+) wereprepared and the five crystal structures were all determined by X-ray diffraction. Metal ions in thefive structures are of six-membered coordination. The demethylcantharate ions can act as a tri-,tetra- or penta-dentate ligand toward metal ions to form ion-pair structure, chain structure or threedimensional polymer structure respectively. The bridge oxygen atom in ligand always participatesin coordination. In the structures of KM(C_8H_8O_5)_2·6H_2O, the formal valence of M (Ni, Co) is+3, but the data of crystal structures show that M are M~(2+) ions and Ni may form a Ni~(2+) -stabilizedligand radical. In addition, the metal ions are assumed to be probes and some possible Interactionsbetween the acceptor and the receptor are discussed.     

Separation of Neutral Amino Acids with Ligand Exchange Resins

Four neutral amino acids (Gly, Ala,.Val and Leu) were separated with ligand exchange resins. The separation capacity of the ligand exchange resins is compared with that of common ion exchange resins. The effects of eluent, column temperature, and central metal ions of the support on the separation are studied. The relationship between matrix structure of resins and their separation capacity is analysed.     

Study on Stability of Nateglinide Polymorphism

The stability of three forms of nateglinide, especially S-form and H-form, was determined. S-form was a new crystal structure of nateglinide. Three forms of nateglinide were treated in different conditions, such as in various temperatures, humidity, light and so on.Analysis of their crystal structures was performed by X-ray powder diffraction ( XRD ) and their particle shapes were observed with scanning electron microscope ( SEM ). The results indicated that the stability of S-form of nateglinide is the best among the three forms and their particle shapes are quite difference. S-form is the sheet structure of layer upon layer, H-form looks like a hank of silk lines and B-form is the clubbed shape.     

A New Method of Synthesis of Azo Schiff Base Ligands with Azo and Azomethine Donors: Synthesis of N-4-Methoxy- benzylidene-2-(3-hydroxyphenylazo)-5-hydroxy- aniline and Its Nickel(II) Complex

A new method for the synthesis of azo Schiff an base ligand in which the azo and azomethine groups are coordination sites was developed through a Schiff base precursor. The precursor, N-4-methoxybenzylidene-3-hydroxy- phenylamine (SB) derived from 3-aminophenol was regioselectively coupled with a diazonium ion para to the hydroxyl group of the amine component of the Schiff base. The para selectivity was controlled by the directing effect of the hydroxyl group. The ligand and its nickel(II) complex were characterized by elemental analyses, IR and UV-Vis spectroscopy. The analytical and spectral data supported the mononuclear formulation of the complex with metal to ligand ratio (M∶L＝1∶2) and suggested a square planar geometry for the complex.