Synthesis and Crystal Structure of a Novel 2-Fold Interpenetrating Three-dimensional Coordination Polymer,{[Co_3（byip）_2（bix）_3（H_2O）_2]·H_2O}_n

The title coordination polymer including two crystallographically independent Co2+ ions is hydrothermally synthesized, in which the Co(1) 2+ ion is four-coordinated by two carboxylate oxygen atoms from two different 5-(benzoic acid-4-yldiazenyl)isophthalate (byip3-) anions and two nitrogen atoms from two distinct 1,4-bis(imidazol-1-ylmethyl) benzene (bix) ligands displaying a tetrahedral geometry. The Co(2) 2+ ion is six-coordinated by two water molecules at the apical positions, and two carboxylate oxygen atoms and two nitrogen atoms at the equatorial positions, affording a slightly distorted octahedron. Two Co(1)2+ and two Co(2)2+ ions are linked together by four byip3- anions forming a 44-membered motif and these motifs are further arranged into a three-dimensional framework through bix ligands along the a axis with a larger channel (ca. 22.70×11.01). Each individual network interpenetrates with the other identical network in a parallel fashion to generate a 2-fold interpenetrating array with the {62.84}{63}2{64.82}2 topology.     

酰胺氮桥联双核钴(Ⅲ)配合物[Co2(bpmb)2(CN)2]·H2O的合成、分子结构和超分子组装

合成了1个酰胺氮桥联的双核钴(Ⅲ)配合物[Co2(bpmb)2(CN)2].H2O(bpmb2-=1,2-bis(pyridine-2-carboxamido)-4-methylbenze-nate)(1),并通过X-射线单晶衍射分析表征其结构特征。结果表明:吡啶甲酰胺配体H2bpmb的甲酰胺氮原子脱去氢原子形成带两个负电荷的扭曲的四配位螯合配体bpmb2-。1个钴(Ⅲ)离子与2个吡啶氮原子,2个bpmb2-配体上的桥联酰胺氮原子和2个氰基碳原子配位得到六配位、变形的八面体CoN4C2;另1个钴(Ⅲ)离子与2个吡啶氮原子,配体bpmb2-上的2个未桥联甲酰胺氮原子和2个桥联的甲酰胺氮原子六配位,形成扭曲的八面体CoN6配位构型。[Co2(bpmb)2(CN)2]单元通过自由水分子和氰基氮原子和甲酰胺氧原子之间O-H…N和O-H…O氢键形成锯齿型链状超分子亚结构,这些链状亚结构通过π-π相互作用连接起来形成网状的超分子结构。     

吡啶-3-甲醛缩氨基硫脲合镍(Ⅱ)、锌(Ⅱ)配合物的合成、晶结构及生物活性

本文合成并表征了吡啶-3-甲醛缩氨基硫脲(HL)合镍(Ⅱ)、锌(Ⅱ)配合物.在配合物[NiL2(1)中,镍(Ⅱ)离子与来自2个脱氢配体的2个氮原子和2个硫原子配位.形成四配位的平面正方形构型.在配合物[Zn(HL)2(C2H5OH)2(H2O)2](NO3)2(2)中,锌(Ⅱ)离子与2个中性配体、2个乙醇分子和2个水分子配位,配位原子在锌(Ⅱ)离子周围形成畸变的八面体构型.通过荧光吸收法研究了配合物1、2与小牛胸腺DNA的作用机理.结果表明,这2个配合物均以插入形式进入DNA的碱基对.此外,还研究了配体及2个配合物对金黄色葡萄球菌、乙型溶血性链球菌、肺炎链球菌、炭疽杆菌的抗菌活性.结果表明,配体及配合物1对上述测试菌种无抑制作用.配合物2对前面3种有弱的抑菌作用.     

Preparation of two new liquid chromatographic chiral stationary phases based on diastereomeric chiral crown ethers incorporating two different chiral units and their applications

Two new liquid chromatographic chiral stationary phases based on diastereomeric chiral crown ethers incorporating two different chiral units such as optically active 3,3'-diphenyl-1,1'-binaphthyl and tartaric acid unit were prepared. Between the two CSPs, one was much superior to the other especially in the resolution of tocainide and its analogues (for example, in the resolution of tocainide the separation factor, alpha, was 4.26 vs. 1.00 on the two CSPs). From these results, the two chiral units composing the two diastereomeric chiral crown ether moieties of the stationary phases were expected to show "matched" or "mismatched" effect on the chiral recognition according to their stereochemistry. The different chiral recognition abilities of the two CSPs were rationalized by the different three-dimensional structures of the two diastereomeric chiral crown ethers.     

Chemical constituents of Taraxacum formosanum

Three new compounds, taraxacine-A (1), taraxacine-B (2) and taraxafolin (3) together with twenty-five known compounds, which include two beta-carboline alkaloids, two indole alkaloids, two chlorophylls, two flavonoids, one coumarin, two triterpenoids, one monoterpenoid, one ionone, four steroids and eight benzenoids, were isolated and characterized from the fresh aerial parts of Taraxacum formosanum. Structures of new compounds were determined by spectral analysis.     

A method for creating a non-equilibrium NT(P1-P2) ensemble in molecular dynamics simulation

A method is proposed for creating a non-equilibrium ensemble with a constant number of molecules, constant temperature and constant pressures with different target values in two reservoirs [referred to as NT(P(1)-P(2)) ensemble] that are connected by a finite length nanopore. This method includes two steps. The first step places a partition between the two reservoirs and then creates a static pressure field and a proper system volume by using two self-adjusting plates on which two external forces/pressures with different target values are exerted. The second step removes the partition and the two self-adjusting plates and the pressure difference between the two reservoirs is maintained by a "pump" designed to simultaneously create a periodic boundary condition between the two reservoirs and supply the necessary force (work) to a subset of molecules for a steady state flow. To examine this method, several cases using liquid argon with a truncated and shift Lennard-Jones potential under different target pressures and pump sizes were studied. Results show that the method proposed in this paper works well. In addition, the method proposed in this paper was compared with the other external force field methods. The results show that as long as the external force is applied to a restricted set of molecules away from the channel a constant pressure difference between two reservoirs is maintained. The advantage of the algorithm proposed here also sets the absolute pressures with different target levels in two reservoirs instead of it being arbitrary. Studies show that the fluid flow rate or permeability through a nanopore depends not only on the pressure difference between two reservoirs, but also on the absolute pressures in two reservoirs.     

2，2-联吡啶-3，3-二羧酸桥联的具有2D网格结构的Mn配位聚合物的合成、晶体结构

A Manganese(Ⅱ) polymer {[Mn(bpdc)(bipy)(H₂O)]·4.5H₂O}_n has been synthesized (bpdc=2,2-bipyridine-3,3-dicarboxylate,bipy=4,4-bipyridine) and characterized by IR, UV, elemental analysis and X-ray crystal structure determination . It crystallizes in Monoclinic system, space group P2/n with a=1.010 13(8) nm, b=1.164 66(9) nm, c=2.147 40(16) nm, β=98.22 20(10)°, V=2.500 4(3) nm³, Z=4, D_c=1.467 g·cm^-3, F(000)=1 144, R₁=0.049 0, wR₂=0.141 2. The crystal structure shows that the Mn²⁺ ions have octahedral coordination geometry with two coordination situations. The Mn²⁺ (1) ion is coordinated with two N atoms of two bipy, and chelated by four O atoms from four carboxylate groups of two bpdc ligands. The neighbor Mn²⁺ (2) ion is coordinated with two oxygen atoms from two water, two N atoms of two 4,4-bipy and two O atoms from two carboxylate groups of two bpdc ligands. Mn(1) and Mn(2) ions are bridged by bpdc and bipy ligands, forming a novel 2D network. CCDC: 651043.     

Proton-ionizable crown compounds. 19. The synthesis of chiral dialkyl-substituted triazolo-18-crown-6 macrocycles

Four new chiral macrocyclic polyether ligands containing the proton-ionizable triazole subcyclic unit have been prepared. The triazolo-crowns contain two isopropyl, two isobutyl, two (S)-sec-butyl or two benzyl substituents on chiral macro ring carbon atoms. A racemic triazolo-18-crown-6 containing two (1-naphthoxy)methyl substituents was also prepared.     

MOLECULAR RIBBONS COMPOSED OF CALCIUM(II) IONS BRIDGED BY CARBOXYLATE AND WATER OXYGEN ATOMS IN THE CRYSTALS OF Ca(II) COMPLEX WITH 5-METHYLPYRAZINE-2-CARBOXYLATE LIGANDS

Abstract

Crystals of monoaquo(μ-5-methylpyrazine-2-carboxylato-N,O,O′), (5-methylpyrazine-2-carboxyato-N,O)di(μ-aquo-O,O)calcium(II) contain molecular ribbons in which two adjacent calcium(II) ions are bridged by two bidentate oxygen atoms donated by two ligand molecules on one side and bidentate oxygen atoms of two water molecules on the other. The coordination polyhedron around the Ca(II) ion is a pentagonal bipyramid. The vertices of its pentagonal base are composed of two bridging water oxygen atoms, two carboxylate oxygen atoms of two ligand molecules and a nitrogen atom belonging to one of the bridging ligands. A coordinated water molecule constitutes the apex of the pyramid on one side of the base, while the N, O bonding moiety of a second ligand molecule makes two apices on the other side of the base. The ribbons are held together by a system of hydrogen bonds.     

Domains in bovine seminal ribonuclease

Bovine seminal ribonuclease is the only pancreatic-type ribonuclease to possess a dimeric structure: the two identical subunits are covalently linked by two disulfide bridges. Actually, the protein exists in two different dimeric structures owing to the possibility of swapping the N-terminal α-helical segments: the swapped MxM dimer, and the non-swapped M=M dimer. The thermal denaturation of the two separated forms is investigated by differential scanning calorimetry. The process is reversible and can be represented by two sequential two-state transitions, indicating the presence of two domains in BS-RNase, regardless of the swapping phenomenon. Inspection of the structural models leads to the tentative identification of an external domain and a core domain, the latter more stable.     

Isolation and purification of isoflavonoids from Rhizoma Belamcandae by two‐dimensional preparative high‐performance liquid chromatography with column switch technology

A two‐dimensional column‐switching system without sample loop trapping, where two columns were operated via a six‐port switching valve, was employed in the isolation and purification of five isoflavonoids from Rhizoma Belamcandae: tectoridin, iridin, tectorigenin, irigenin and irisflorentin. The introduction of the six‐port switching value, instead of a sample loop, assured 100% recovery from the first dimension to the second, and the injection volumes of the second dimension were not restricted. Two configurations were tested in this study. In the first mode, only one column was used in the second dimension and two ‘heart‐cutting’ fractions were transported to the same second‐dimensional column. In the second mode, two parallel columns were used in the second dimension and two fractions were transported to the two columns. Between the two configurations, the one with two second dimensional columns had double sample size, better resolution and one more purified compound. Both two‐dimensional configurations consumed less solvent with even greater efficiency and shorter cycle time compared with conventional gradient methods. All of the isoflavonoids were isolated at high purities of greater than 95% with yields of above 82%. Copyright © 2009 John Wiley & Sons, Ltd.     

Hyaluronidase inhibitors from Keiskea japonica

An extract of Keiskea japonica MIQ. showed an inhibitory effect on hyaluronidase activity. From the extract, four new phenylpropanoids, two new maltol glycosides, two new monoterpene glycosides, and two new phenolic compounds were isolated together with 19 known compounds. Among these constituents, two phenylpropanoids and a flavone glucuronide were revealed as hyaluronidase inhibitors.     

A theory for long-lived high-energy excitation of a local mode using two lasers

Quantum-mechanical calculations on a realistic system show that excitation of a local mode may be accomplished by using two lasers. More importantly, this local mode does not decay into the bath modes of the molecule even at very long times. This excitation is accomplished using two lasers tuned to two eigenstates whose wavefunctions interfere to give the local excitation. Most significantly, this observation for a model system implies that mode specific control of chemical reactions may be accomplished using two lasers to excite two overtone transitions.     

Dendrimer with rotaxane-like mechanical branching

[reaction: see text] A dendrimer wherein the branching points are mechanical in nature has been synthesized. It contains two identical covalently linked bis-dendrons and a core unit fused to two rings that encircle the two bis-dendrons. A "threading-followed-by-stoppering" approach is used in the template-directed synthesis of a precursor bis[2]rotaxane, which undergoes stopper exchange four times to yield the dendrimer in which the two bis-dendrons act as stoppers within the two [2]rotaxane subunits.     

Diketopyrrolopyrrole‐Porphyrin Conjugates with High Two‐Photon Absorption and Singlet Oxygen Generation for Two‐Photon Photodynamic Therapy

Two‐photon photodynamic therapy is a promising therapeutic method which requires the development of sensitizers with efficient two‐photon absorption and singlet‐oxygen generation. Reported here are two new diketopyrrolopyrrole‐porphyrin conjugates as robust two‐photon absorbing dyes with high two‐photon absorption cross‐sections within the therapeutic window. Furthermore, for the first time the singlet‐oxygen generation efficiency of diketopyrrolopyrrole‐containing systems is investigated. A preliminary study on cell culture showed efficient two‐photon induced phototoxicity.     

Regioselective synthesis of antiparallel loops on a macrocyclic scaffold constrained by oxazoles and thiazoles

The regioselective syntheses and structures are reported for two tris-macrocylic compounds, each possessing two antiparallel loops on a macrocyclic scaffold constrained by two oxazoles and two thiazoles. NMR solution structures show the loops projecting from the same face of the macrocycle. Such molecules are shown to be prototypes for mimicking multiple loops of proteins.[structure: see text]     

茂铁基稀土铈配合物的合成与结构

本文利用单羧基二茂铁Fc-COOH和1，1′-二羧基二茂铁HOOC-Fc-COOH作为配体分别合成了双核铈配合物Ce₂(FcCOO)₆ (1)和二维层状配位聚合物Ce₂(OOC-Fc-COO)₃(2)，测定了两种配合物的晶体结构。配合物1中的金属铈离子为九配位结构，分别与周围的羧基二茂铁上的氧原子和作为辅助配体的水分子配位，茂铁间的π-π相互作用将配合物1的二聚体单元连结在一起形成二维的网状结构。配合物2中的金属铈离子亦为九配位结构，分别与周围的羧基二茂铁上的氧原子，作为辅助配体的水分子和甲醇配位形成类似于配合物1的二聚体单元，1，1′-二羧基二茂铁HOOC-Fc-COOH作为桥基配体将二聚体单元连结在一起，形成二维网状的配位聚合物。     

A first principle study of adsorption of two proximate nitrogen atoms on graphene

Different possible configurations of two nitrogen‐adatoms on graphene are studied using density functional theory. Adsorption of single nitrogen atom on the bridge site of graphene is accompanied by distortion of the sheet. Electronically, this case amounts to p‐type doping. Two N atoms adsorbed on the graphene sheet can share a bond in two ways. They acquire positions either just above two adjacent carbon atoms or they form a bridge across opposite bonds of a hexagon in the sheet. Both these configurations also induce structural distortion of the sheet. Another stable configuration consists of two N atoms bonded as an N₂ molecule physisorbed on the graphene sheet. It is also possible to adsorb two N atoms on opposite sides of the graphene sheet, bonded to the same two C atoms. Moreover, two N atoms can be individually adsorbed on alternate bridge sites of neighboring hexagons experiencing a repulsion, the energy for which arises from the additional distortion of the graphene sheet. The densities of states near the Fermi level are found to be dependent on the adsorption configurations of two nitrogen atoms on graphene. Thus the electronic properties of graphene can be controlled by the selective adsorption of two nitrogen atoms. © 2014 Wiley Periodicals, Inc.     

含2-苯氧基丙酸根的镍、锌配位聚合物的合成与晶体结构

用溶液法和水热法分别合成了2个含2-苯氧基丙酸配体(HL)的聚合物{[NiL2(H2O)2(bipy)].2H2O}n(1)、{[ZnL2(bipy)].2H2O}n(2)(bipy=4,4′-联吡啶),用元素分析、红外光谱、热重和单晶X-射线衍射对产物进行了表征。在化合物1中,镍原子与2个羧基氧原子、2个配位水氧原子及2个4,4′-联吡啶的2个氮原子配位,配位数为6,镍原子的配位构型为畸变的八面体;而在化合物2中,锌原子与2个羧基氧原子及2个4,4′-联吡啶中的2个氮原子配位,锌原子的配位构型为畸变的四面体。在这2个化合物里,4,4′-联吡啶通过氮原子连接金属原子形成一维链状。链间氢键与π-π堆积作用又将一维链链接成二维层状结构。