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61.
A sequential use of halogenation, SNAr, Sonogashira and/or Suzuki couplings together with the use of either mono-5-, 5,15- or 5,10-di-meso-substituted porphyrins allows the facile construction of unsymmetrical porphyrin dimers and trimers with different spatial orientation. The protocols established allow a convenient entry into multichromophores suitable for application in nonlinear optics and biomedicine. 相似文献
62.
Ergin Yalçin Marija Matković Marijana Jukić Ljubica Glavaš Obrovac Ivo Piantanida Zeynel Seferoğlu 《Tetrahedron》2018,74(5):535-543
A series of structurally similar 1-substitued heteroaryl fluorene derivatives were prepared in a simple single step reaction, oxidized to fluorenones and then both, fluorenes and fluorenones, were methylated to enhance the solubility and increase the affinity to DNA/RNA. Interactions of both, fluorene and fluorenone analogues with various ds-DNA, ds-RNA revealed strong ds-DNA/RNA binding, and various thermal stabilization effects. Most intriguingly, some fluorene derivatives showed opposite fluorescence change (increase for ds-RNA and decrease for ds-DNA), which was not previously reported for any fluorene analogue. CD experiments along with other methods support ds-DNA minor groove binding and major groove ds-RNA binding. All compounds showed negligible interaction with G-quadruplex DNA. Very low cell cytotoxicity of studied compounds combined with very efficient cellular uptake makes these fluorescent dyes safe for laboratory applications. Moreover, especially compounds which show opposite fluorescence response to ds-DNA and ds-RNA, are promising lead compounds for further studies aimed toward ds-RNA-specific fluorescence markers. 相似文献
63.
64.
Three isonicotinamide (isn) copper(II) complexes with different bridging ligands, azide, thiocyanate and sulfate, have been prepared. The molecular structure of [Cu2(μ-1,1-N3)2(μ-1,3-N3)2(isn)2]n (1) is composed of binuclear species, Cu2(μ-1,1-N3)2(isn)2, inter-connected by additional four azide bridges in the end-to-end mode (1,3). This gives a CuN4N square-pyramidal coordination sphere around each copper(II) ion. A trans mononuclear octahedral coordination sphere CuN4S2 is present in [Cu(μ-N,S-NCS)2(isn)2]n (2), with thiocyanato ligands serving as bridges between the adjacent Cu(isn)2 moieties. The third anionic ligand, i.e. sulfate, in {[Cu(μ-O,O’-SO4)(H2O)(isn)2]·2H2O}n (3) completes the CuO2N2O square-pyramidal coordination sphere, and thus enables bridging between the mononuclear Cu(H2O)(isn)2 moieties. The ligands that bridge the principal building blocks, i.e. binuclear in 1 and mononuclear in 2 and 3, connect the axial ligands with the equatorial positions of the copper(II) coordination spheres in all three cases. A ferromagnetic interaction FM is found for 1, while 2 and 3 are paramagnetic. Therefore, the key structural difference between 1 on one hand, and 2 and 3 on the other, is found in the anionic ligand, serving in 1 also as the intra-binuclear bridge, showing the main path (J1) for the FM interaction. Additionally, the inter-binuclear pathway in 1 gives another contribution (J2) to the whole FM interaction seen herein (J1 = 18.5 cm–1, J2 = 4.9 cm–1). 相似文献
65.
Abstract
The synthesis, thermal and spectral characterization and crystal structure of silver(I) complex with picolinamide, [Ag(C6H6N2O)2](NO3)·H2O, are reported. The silver(I) atom is chelated by two picolinamide (pia) ligands in approximately square planar geometry. The distortion within the coordination environment is mainly imposed by formation of the chelate rings, but it is also observed in two longer (Ag–O) and two shorter (Ag–N) bond lengths. The compound crystallizes in the triclinic space group P[`1]P\bar{1} with a = 7.1265(2) ?, b = 8.9157(4) ?, c = 12.9527(4) ?, α = 83.934(3)°, β = 86.094(2)°, γ = 67.023(3)° and Z = 2. Cationic complexes are linked through amide–amide hydrogen bonds of ‘head-to-head’ R 22(8) motif leading to infinite chains, while nitrate anions and H2O molecules act only as a cross-link between such four symmetry related cationic chains via hydrogen bonds forming 2D supramolecular double sheets. Therefore, the ‘head-to-head’ amide interactions in [Ag(C6H6N2O)2](NO3)·H2O are robust enough to accommodate the usually disruptive NO3 − anion and H2O molecule and could be regarded as a tool for controlling the assembly of this silver complex. 相似文献66.
Josic D Breen L Clifton J Gajdosik MS Gaso-Sokac D Rucevic M Müller E 《Electrophoresis》2012,33(12):1842-1849
Sample displacement chromatography (SDC) in reversed-phase and ion-exchange modes was introduced approximately 20 years ago. This method was first used for the preparative purification of peptides and proteins. Recently, SDC in ion-exchange mode was also successfully used for enrichment of low-abundance proteins from human plasma. In this paper, the use of SDC for the separation of plasma proteins in hydrophobic interaction mode is demonstrated. By use of two or more columns coupled in series during sample application, and subsequent elution of detached columns in parallel, additional separation of bound proteins was achieved. Further low-abundance, physiologically active proteins could be highly enriched and detected by ESI-MS/MS. 相似文献
67.
Marijana ?akovi Zora Popovi 《Acta Crystallographica. Section C, Structural Chemistry》2009,65(9):m361-m366
The title compounds, trans‐diaquabis(nitrato‐κO)bis(pyridine‐4‐carboxamide‐κN1)copper(II), [Cu(NO3)2(C6H6N2O)2(H2O)2], (I), and trans‐diaquatetrakis(pyridine‐4‐carboxamide‐κN1)copper(II) bis(perchlorate), [Cu(C6H6N2O)4(H2O)2](ClO4)2, (II), are composed of mononuclear coordination entities involving CuII ions and isonicotinamide. In (I), the centrosymmetric tetragonally distorted octahedral copper(II) environment contains trans‐related isonicotinamide and water molecules in the equatorial plane and two nitrate ions occupying the axial sites. In (II), the equatorial plane of the C2‐symmetric distorted octahedron is built up of four isonicotinamide ligands, while water molecules occupy the axial positions. The complex molecules of (I) and (II) are linked into three‐dimensional supramolecular frameworks by O—H...O and N—H...O hydrogen bonds. The nitrate and perchlorate ions are building blocks that disturb the robust R22(8) amide supramolecular motif commonly found in crystal structures of copper–isonicotinamide complexes. 相似文献
68.
Alcoholism is a medical, social, and economic problem where treatment methods mostly include difficult and long-lasting psychotherapy and, in some cases, quite controversial pharmacological approaches. A number of medicinal plants and pure natural compounds are reported to have preventive and therapeutic effects on alcoholism and alcohol dependency, but their constituents, efficacy and mechanism of action are mostly unknown so far. Recently, kudzu [Pueraria lobata (Willd.) Ohwi], St. John's wort (Hypericum perforatum L.), danshen (Salvia miltiorrhiza Bge.), ginseng (Panax ginseng C.A. Mey.), Japanese raisin tree (Hovenia dulcis Thunb.), ibogaine (Tabernanthe iboga H. Bn.), evening primrose (Oenothera biennis L.), prickly pear fruit (Opuntia ficus indica (L.) Mill.), purple passionflower (Passiflora incarnata L.), thyme (Thymus vulgaris L.), fenugreek seed (Trigonella foenum-graecum L.), ginger (Zingiber officinale Roscoe) and many others drew the attention of researchers. Can, therefore, drugs of natural origin be helpful in the treatment of alcoholism or in decreasing alcohol consumption? 相似文献
69.
Damir Vukicevic Milan Randic Alexandru T. Balaban 《Journal of mathematical chemistry》2004,36(3):271-279
A rigorous proof is provided for the theorem on the necessary and sufficient conditions for the algebraic Kekulé structure of a peri-condensed or corona-condensed benzenoid hydrocarbon to correspond to more than one geometric Kekulé structure. 相似文献
70.
Brgles M Clifton J Walsh R Huang F Rucevic M Cao L Hixson D Müller E Josic Dj 《Journal of chromatography. A》2011,1218(17):2389-2395
Human serum albumin (HSA) and immunoglobulin G (IgG) represent over 75% of all proteins present in human plasma. These two proteins frequently interfere with detection, determination and purification of low abundance proteins that can be potential biomarkers and biomarker candidates for various diseases. Some low abundance plasma proteins such as clotting factors and inhibitors are also important therapeutic agents. In this paper, the characterization of ion-exchange monolithic supports under overloading conditions was performed by use of sample displacement chromatography (SDC). If these supports were used for separation of human plasma, the composition of bound and eluted proteins in both anion- and cation-exchange mode is dependent on column loading. Under overloading conditions, the weakly bound proteins such as HSA in anion-exchange and IgG in cation-exchange mode are displaced by stronger binding proteins, and this phenomenon was not dependent on column size. Consequently, small monolithic columns with a column volume of 100 and 200 μL are ideal supports for high-throughput screening in order to develop new methods for separation of complex mixtures, and for sample preparation in proteomic technology. 相似文献