Synthesis, Crystal Structure and Spectroscopic Properties of an Octanuclear V-S-Cu Cluster {V_2S_6Cu_6}(PPh_3)_6(O)_2·2CH_2Cl_2·CH_3OH with a Metal-sulfur Dodecahedral Cage

1 INTRODUCTION The reactivities of the thiometalates [MOnS4-n]z－ (n=0~2) and their applications in synthetic chemistry are very attractive because they have been shown to act as multi-ligands to a wide variety of metal ions[1]. The chemistry of Mo(W)S clusters derived from thiometalates has been most highly developed[2] for some MoS clusters are closely relevant to biological activities[3,4]. As for thiovanadates, only [VS4]3－ species has been used as ligands to coordinate metal at…     

A Novel Way to Prepareγ-A1_2O_3 Supported SO_4~(2-)/ZrO_2 Solid Superacid Catalysts for n-Butane Isomerization

The isomerization of n-butane to isobutane, which is a valuable precursor for theproduction of MTBE and alkylated gasoline, on strong acid catalysts is an importantprocess in refining industry. Solid superacid, especially sulfated zirconia, has highcatalytic activity in n-butane isomerization at comparatively low temperatures andtherefore has attracted more attention of researchers in the past twenty years.' However,from the view point of practice, the activity of SZ needs to be improved fur…     

Synthesis and Crystal Structure of a Novel Two-dimensional Layered Polymer [Zn（μ-O2CCH=CHCO2）（C3H4N2）（H2O）]n

1 INTRODUCTION More than 200 known metalloenzymes of a wide variety of types have been shown to contain zinc centers at their active sites (such as hydrolases, ligases and anhydrases)[1～3]. The active zinc centers in biological systems are usually surro…     

Synthesis and Crystal Structure of Lanthanide Schiff Base Complex [2-OC6H4CHN（2,6-i-Pr2C6H3）]2ErCl（THF）

1 INTRODUCTION The Schiff base ligands have been used to provide a stereochemically rigid ligand framework in homogenous precatalysts of some metals, such as salen Cr catalysts in asymmetric ring-opening re- action of epoxide[1] and salen Al in ring-opening polymerization of lactide and related cyclic esters[2]. Recently, it was reported that the bidentate Schiff base complexes of early and late transition metals can be served as promising alternatives to metal- locene catalysts for th…     

Enamine Configuration of 5-Methyl-2-phenyl-4-[（Z）-3-tolylamino-phenylmethylene]pyrazol-3（2H）-one

1 INTRODUCTION In contrast to the old-line academic and practical studies of 1-phenyl-3-methyl-4-benzoyl-5-pyrazo- lone (PMBP) on the metal coordination chemistry[1], the complexes of β-ketoamines derivated from PMBP received little attention due to its complicated com- plexation. However, in recent years, there has a sudden growth of this area as a result of its timely interest in biological activities[2]. Recently, a series of β-ketoamines[3] containing PMBP have been prepared fro…     

Theoretical insights into the [4 + 2]/retro [4 + 2] cycloaddition approach to the synthesis of biaryls and polycyclic aromatics

A domino [4+2]/retro [4+2] cycloaddition process of cyclohexadienes with arylethynes or benzyne providing access to biaryls and polycyclic aromatics has been studied theoretically using density functional theory calculations. It has been found that the initial Diels-Alder (D-A) reaction acts as the rate-determining step and the consequent [4+2] cycloreversion reaction is feasible under the conditions used. Furthermore, the D-A reaction affects the regioselectivity, the origin of which is essentially derived from the good match of orbital coefficients between dienes and dienophiles as shown by using frontier molecular orbital (FMO) theory. Further investigation of the reactivity reveals that the reactions are predicted to fail to occur if an electron-donor group in the diene or an electron-acceptor group in the dienophile is lacking, as a consequence of the increased FMO energy gap. By further exploring the scope of substrates computationally, benzyne as an active dienophile was predicted to react with a variety of dienes in a cascade reaction under mild conditions with a low energy barrier, with the rate-determining step being the retro [4+2] cycloaddition.     

Three New Zn(Ⅱ)/Cd(Ⅱ) Coordination Polymers Constructed with 2-Mercaptonicotinic Acid and 1,2-Di(4-pyridyl)ethylene: Syntheses and Structure Analysis

Three new Zn(Ⅱ)/Cd(Ⅱ) coordination polymers based on 2-mercaptonicotinic acid (H2mna) with 1,2-di(4-pyridyl)ethylene (dpe) introduced as a bridging ligand have been synthesized via hydrothermal method and structurally characterized by single-crystal X-ray diffraction as well as elemental analysis and IR. As reported in this paper, [Zn2(dpe)0.5(mna)2] (1) can be classified as a two-dimensional layer structure in which the 1D chain composed of Zn(Ⅱ) and mna ligands is bridged by dpe ligands, while the complex named [Zn4(dpe)4(mna)4] (2) is a tetra-nuclear cluster compound. These two compounds are further extended to three-dimensional structures by hydrogen bonds along with C-H…π and π…π interactions. Compound 3 with general formular [Cd2(dpe)0.5(mna)2]·H2O belongs to a three-dimensional porous structure in which the 2D metal layers formed by the coordination of Cd(Ⅱ) and mna ligands are connected with the bridging of dpe ligands.     

Study on the Ring Eulargment Reaction: Synthesis of 7,8,13, 13a-tetrahydroisoindolo[1,2-b][3]benzazepine and 5,6,8,9,14,14a-hexahydroisoquino[1,2-b][3]benzazepine

In our research on the ring enlargement of certain N-heterocycles, a general procedure for the ring enlargement with the insertion of an extra -CH2- was improved and shown in Scheme I1.Scheme IThe procedure had been carried out with such N-heterocycles as 2-methyl-1,2,3,4-tetrahydroisoquinoline2, tetrahydroberberine and strychnine3 with expected results. Thus, the procedure shown in Scheme I provides a new approach to the synthesis of larger N-heterocycles.Isoindolo[1,2-b][3]benzazepines a…     

SO2-4/ZrO2对Rh/γ-Al2O3-Zr催化剂上乙烯选择还原NO反应的影响

The selective reduction of NO by hydrocarbons in the presence of excess oxygen is a potential route to remove NO from exhaust gases[1,2]. The acidity has been shown to be important in lean NO reduction, and the role of acidity in this reaction is quite different for various catalytic systems[3～9]. In this paper, 15%ZrO2 as the thermal stabilizer is doped into 0.5%Rh/γ-Al2O3, and the synergetic effect between Rh/γ-Al2O3-Zr and solid superacid SO2-4/ZrO2 for NO+C2H4+O2 reaction is studied.     

Studies on β2-Glycoprotein Ⅰ Recognizing Molecules from a Phage Peptide Library

β2-Glycoprotein I(β2-GPI) has been identified as a cofactor in the recognition of phospholipid Ag cardiolipin (CL) by anticardiolipin Ab(aCL) purified from patients' serum with autoimmune disease. However, there is a considerable controversy as to the anti-β2-GPI -antibodies occurred in aCL. In order to select β2-GPI recognizing molecules, β2-GPI was used as a probe to screen affinity phage clones panned from a phage peptide library. After four cycles of selection, the phage recovery increased from 2.4×10-5% to 1.1×10-3%, indicating that a specific enrichment had been achieved. In order to characterize these phage clones, we investigated their specific binding to β2-GPI and their inhibition of β2-GPI binding to anti-β2-GPI antibodies. Almost 40 percent of clones reflected considerable binding abilities and inhibitory activities towards anti-β2-GPI antibodies. A group of related peptides were identified by DNA sequencing, in which there were seven related peptide sequences, with four of them representing more than once. These peptide sequences display similarities at several positions. Sequence motif (-F-S-L-) was evident in most of the peptides. It suggests that these peptides may specifically block the anti-β2-GPI antibodies binding to β2-GPI. Our result supports the idea that β2-GPI acts as a Ag for these anti-β2-GPI antibodies occurred in the aCL.     

Crystal Structure and Electronic Structure of a Luminescent Compound 2—（2—Pyridyl） Benzimidazole

1 INTRODUCTION Imidazole which is a part of histidine, plays an important role as a ligand in bioinorganic chemistry. Up to now, a variety of coordination compounds with imidazole ligands have been synthesized and characterized[1]. Its complexes have a…     

Synthesis of 2-Arylimidazo[1, 2-a]pyrimidines in Ionic Liquids

Room temperature ionic liquids were used as a “green“ recyclable alternative to conventional solvents in the synthesis of pharmaceutically useful compounds 2-arylimidazo[1, 2-a]pyrimidines through Tschotschibabin reaction of a-bromoacetophenones with 2-aminopyrimidine in good yields.     

Syntheses and Crystal Structures of Methyl 2-（4,5-Dibromo- 1-methylpyrrole-2-carbonylamino）-3-phenyl propanoate and 4,5-Dibromo-1-methyl-2-trichloroacetylpyrrole

1 INTRODUCTION Pyrrole and its derivatives have attracted much attention due to their chemical properties as well as biological activities[1]. They have been widely used as the materials to produce pharmaceutical, essences, biochemicals, etc. It has been found that a great deal of pyrrole derivatives present bioactivities, such as antitumor and antiviral activities[2~5]. Thus, due to the interest in exploring the syntheses of potential bioactive materials which contain pyrrole ring andna…     

Study on the effects of cefotaxime on intracellular Ca^2＋ in human peripheral lymphocytes by fluoremetry

Characteristic of Fura-2-Ca~(2 )interaction was studied based on the fluorescence technique.The apparent dissociation constants(K_d)of the Fura-2-Ca~(2 )complex were determined at different temperature.The effect of cefotaxime(CEFA)on intracellular Ca~(2 )concentration([Ca~(2 )]_i)was discussed by using a ratiometric fluorescence dye Fura-2 as a probe.The basal[Ca~(2 )]_i in resting humanperipheral lymphocytes was 100 7 nmol/L but after treatment with cefotaxime,the changes of[Ca~(2 )]_i were observed in differentconditions.In the concentration range of 1-30 μmol/L of cefotaxime[Ca~(2 )]_i increased,as a result of releasing intracellular Ca2 stores.Higher concentration of cefotaxime(50-500 μmol/L)stimulated to decrease of[Ca~(2 )]_i.     

Total Synthesis of (±)-Celaphanol A

Celaphanol A was a diterpene isolated from the stems of Celastrus stephanotifolius1, which have been the subject of continued and growing interest, due to the range of biological activities shown by many members of this family2. Some have been used in traditional medicine3 or as a stimulant4 from ancient times. In order to further study the relationship between the structure and biological activity of the diterpene compound and as an extension of diterpenoid synthesis in our laboratory5, 6, …     

Synthesis and Structure Characterization of Aqua-(μ_2-carbonato-O,O'''')-(2,2''''-bipyridyl)-copper(Ⅱ) Dihydrate

1 INTRODUCTION The class of materials of carbonato metal- organic compounds has received much attention as a consequence of their potential applications in biochemical and environmental protection[1～3]. Many carbonato compounds of Cu2+, Co3+ and Zn2+ etc. have been studied[4～6]. The carbonate anion is a versatile bridging ligand, which can bind metal cations in different modes to generate mononuclear, binuclear, trinuclear, tetranuclear and even 1D, 2D and 3D structures[4, 7, 8]. We…     

Tin(II) Chloride Dihydrate Catalyzed Groebke Condensation: An Efficient Protocol for the Synthesis of 3-Aminoimidazo[1,2-a]pyridines

The ability of tin(II) chloride dihydrate as a catalyst to promote the three-component condensation reaction from a diversity of aromatic aldehydes, 2-aminopyridines and isonitriles at room temperature is described. This methodology affords a number of 3-aminoimidazo[1,2-a]pyridines in the presence of tin(II) chloride dihydrate as a new and mild Lewis acid catalyst in the multi-component reaction in reasonable yields and short reaction time without any significant optimization of the reaction conditions.     

Coordination chemistry of organometallic polydentate ligand Reactive chemistry of the tridentate ligand trans-Fe(Ph_2PQu-P)_2- (CO)_3 [Ph_2PQu=2-diphenyl-phosphino-4-methylquinoline] and molecular structure of [Fe(CO)_3(μ-Ph_2PQu)_2HgI]~ [HgI_3]~-

Reaction of a new type of bidentate ligand PhPQu [ PhPQu = 2-diphenylphosphino-4-methylquinoline] with Fe(CO)5 in bu-tanol gave trans-Fe(PhPQu-P)(CO)3 (1).Compound 1,which can act as a neutral tridentate organometallic ligand,was reacted with I B,II B metal compounds and a rhodium complex to give six binuclear complexes with Fe-M bonds,Fe(CO)3(u-Ph2PQu)MXn(2-7) [M=Zn(Ⅰ),Cd(Ⅱ),Hg(Ⅱ),Cu(Ⅰ),Ag(Ⅰ),Rh(Ⅰ)],and an ion-pair complex [Fe(CO)3(n-Ph2PQu)2HgI][HgI3]- (8).The structure of 8 was determined by X-ray crystallography.Complex 8 crystallizes in the space group P-1 with a=1.0758(3),b= 1.6210(4),c = 1.7155(4) nm; a = 75.60(2)β=71.81(2),Y = 81.78(2) and Z = 2 and its structure was refined to give agreement factors of R =0.050 and Rw = 0.057.The Fe-Hg bond distance is 0.2536 nm.     

Photosynthesis and Molecular Structure of2—Amino—3H—phenoxazin—3—one

1 INTRODUCTION 2-Amino-3H-phenoxazin-3-one (APX) is related to the naturally occurring antineoplastic actinomycin D and has been used as a chemical model of actinomycin D[1]. Usually APX is synthesized from 2-aminophenol with the phenoxazinone synthase in human body[2]. A variety of artificial synthesis methods of APX via the oxidation of 2-aminophenol have also been reported, but each method needs some artificial condition such as chemical catalysis[3～7], natural enzyme[8], UV…     

含芯电子相关能修正的G2理论——G2(ful)

A general method in considering the core electronic correlation energies has been proposed and introduced into the standard Gaussian-2 (G2)[7] theory by small post-Hartree-Fock calculations. In this paper an additional MP2(FC)/6-31G(d) calculation over the G2 procedures is employed and examined in modification in modification to the flaw of Frozen-Core (FC) approximation of G2 vai eq.:
ΔE(full)= E[MP2(full)/6-31G(d)]-E[MP2(FC)/6-31G(d)]
where the MP2(full)/6-31G(d) energy has been obtained in the molecular geometry optimizations. This energy, ΔE(full), is directly added into the total G2 energy of a molecule in facilitating the effect of core electronic correlations for each molecule in chemical reactions. It has been shown that the over-all average absolute deviation for the 125 reaction energies of the G2 test set (test set 1) is slightly reduced from 5.09 to 5.01 kJ, mol(-1) while for the 55 D0 values, which have been used for the derivation of the A coefficient of the empirical High-Level...更多-Correction (HLC), it is also reduced from 4.99 [for both G2 and G2(COMPLETE)[8]]to 4.77 kJ• mol(-1). In addition, larger errors (greater than ±8.4 kJ•mol(-1) for the D0 energies are improved, especially for the largest error of the D0 of SO2 This error is reduced from 21.3 to 15.4 kJ. mol(-1), in which the experimental geometry would further reduce it by 7.1kJ.mol(-1)[8]. Another improvement is the absolute value of the A coefficient in HLC being reduced from 4.81 for G2 to 4.34 milli-hartrees which is believed to be useful in isolating the relationship between the HLC and the FC approximation. Modifications to the original G2 from this work is denoted as G2(fu 1) and thus the G2 (fu 1) total energy for a molecule is
E[G2(fu 1)]= E[G2]+Δ E(full)h
with a new ΔE[HLC] =-0.19α- 4.34nβ milli-hartree.