65 research outputs found
Synthesis, biological evaluation, X-ray molecular structure and molecular docking studies of RGD mimetics containing 6-amino-2,3-dihydroisoindolin-1-one fragment as ligands of integrin αIIbβ3
AbstractA series of novel RGD mimetics containing phthalimidine fragment was designed and synthesized. Their antiaggregative activity determined by Born’s method was shown to be due to inhibition of fibrinogen binding to αIIbβ3. Molecular docking of RGD mimetics to αIIbβ3 receptor showed the key interactions in this complex, and also some correlations have been observed between values of biological activity and docking scores. The single crystal X-ray data were obtained for five mimetics
Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR
Substantial experimental and theoretical efforts worldwide are devoted to
explore the phase diagram of strongly interacting matter. At LHC and top RHIC
energies, QCD matter is studied at very high temperatures and nearly vanishing
net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was
created at experiments at RHIC and LHC. The transition from the QGP back to the
hadron gas is found to be a smooth cross over. For larger net-baryon densities
and lower temperatures, it is expected that the QCD phase diagram exhibits a
rich structure, such as a first-order phase transition between hadronic and
partonic matter which terminates in a critical point, or exotic phases like
quarkyonic matter. The discovery of these landmarks would be a breakthrough in
our understanding of the strong interaction and is therefore in the focus of
various high-energy heavy-ion research programs. The Compressed Baryonic Matter
(CBM) experiment at FAIR will play a unique role in the exploration of the QCD
phase diagram in the region of high net-baryon densities, because it is
designed to run at unprecedented interaction rates. High-rate operation is the
key prerequisite for high-precision measurements of multi-differential
observables and of rare diagnostic probes which are sensitive to the dense
phase of the nuclear fireball. The goal of the CBM experiment at SIS100
(sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD
matter: the phase structure at large baryon-chemical potentials (mu_B > 500
MeV), effects of chiral symmetry, and the equation-of-state at high density as
it is expected to occur in the core of neutron stars. In this article, we
review the motivation for and the physics programme of CBM, including
activities before the start of data taking in 2022, in the context of the
worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal
Zeolites embrace metal-organic frameworks: building block approach to the design and synthesis of zeolite-like metal-organic frameworks (ZMOFs)
Our research group has recently developed a novel approach to the design and synthesis of metal-organic assemblies (MOAs), e.g. metal-organic frameworks and metal-organic polyhedra, which has permitted the construction of anionic zeolite-likemetal-organic frameworks (ZMOFs), i.e. rho-ZMOF and sod-ZMOF, serving to merge two important classes of porous functional materials, namely zeolites and metal-organic frameworks (MOFs). Though the use of tetrahedral divalent single-metal ions (M2+) and simple angular monovalent ligands (L–) may lead to MOFs with zeolite-like topologies, the resultant frameworks will be neutral and preclude the use of cationic structure-directing agents (SDAs) and limit the diversity of structures constructed from the same metal ion M(II) and ligand (L–). Our design strategy involves targeting rigid and directional single-metal-ion-based molecular building blocks (MBBs), namely MNx+y(CO2)x+z(containing x N-, O- chelates, y additional N-moieties, and z bridging carboxylates at the remaining open metal sites), where M is a 6- or 8-coordinate metal and the multi-valent, multifunctional ligand is judiciously selected depending on the target structure. The focus of the approach has been to render each hetero-coordinated (N-, O-) single-metal ion, formed in situ, rigid and directional using the N-, O-chelating moieties. For the formation of anionic ZMOFs, an angular ligand (L2-) is utilized where the M-N bonds direct the topology, while the oxygen atoms complete the coordination sphere of the metal and lock it into its position through the formation of rigid five-membered rings via chelation. Our strategy allows for the use of cationic SDAs and thus offers great potential to access the diverse library of known zeolite topologies, including theoretical ones
A {CoIII2DyIII4} Single-Molecule Magnet with an Expanded Core Structure
The coordination cluster compound [CoIII2DyIII4(OH)2(ib)8(bdea)2(NO3)4(H2O)2]·2MeCN (1) self-assembles in a high-yield reaction of cobalt(II) isobutyrate (ib) with Dy(NO3)3·6H2O and N-butyldiethanolamine (H2bdea) in air. The Ci-symmetric {CoIII2DyIII4} core fragment features two {CoDy2(μ3-OH)} triangles, joined by one of their Dy sites via μ-O and μ-carboxylate bridges. This results in a flat zigzag metal skeleton, in contrast to previously reported hexanuclear {Co2Ln4(μ3-OH)2} clusters, namely, exhibiting a more condensed combination of two {CoLn2(μ3-OH)} triangles that form a Dy4 rhombus. According to ac susceptibility measurements, this rearrangement in 1 reduces quantum tunneling of the magnetization and hence pushes up the onset of pronounced out-of-phase signals at zero bias field to 14 K, a significant change vs the more condensed {Co2Dy4} structures. As intermolecular interactions between coordination clusters in the solid state are well-known to also influence SMM features, comparative Hirshfeld surface analyses are also presented. © 2022 American Chemical Society
Zeolite-like Metal−Organic Frameworks (ZMOFs) Based on the Directed Assembly of Finite Metal−Organic Cubes (MOCs)
Two zeolite-like metal−organic frameworks (ZMOFs) with lta- and ast- topologies, zeolitic nets that can be interpreted as augmented edge-transitive 8-connected nets, are targeted through directed self-assembly of metal−organic cubes (MOCs) as supermolecular building blocks (SBBs)
Versatility of Cyclic Triimidazole to Assemble 1D, 2D, and 3D Cu(I) Halide Coordination Networks
Cyclic triimidazole (C 9 H 6 N 6 , L), with C 3h molecular symmetry and three nitrogen atoms available for coordination, is here successfully employed for the first time in the synthesis of coordination compounds. In particular, by varying the reaction conditions (e.g., solvent, temperature, template), seven Cu(I)-halide coordination polymers of different dimensionality are obtained: Two 1D polymers, [CuIL] n (1) and [CuIL]\ub7(I 2 ) 0.5 n (2), three 2D nets, [CuXL] n (X = I, Br) (3-5), and two 3D networks, [CuClL] n (6) and [Cu 3 L 4 ]I 3 n (7). Single crystal X-ray diffraction analysis reveals that the structural versatility of both the ligand and the CuX moiety allows isolating 1D double-stranded stairs in which L is monodentate, 2D layers containing either Cu 2 (\u3bc-X) 2 or Cu 2 (\u3bc-X) moieties and bidentate L ligands, 3D frameworks built up by tridentate L linkers and either monodentate or noncoordinating halogen atoms. The 3D frameworks show nets of srs and bor topologies. The SHG efficiency of powders of 7 (the only noncentrosymmetric derivative of the series) is 10 times higher than that of sucrose. Phosphorescent emission of XLCT character is observed for 1 and 6. \ua
Incorporation of Hexanuclear Mn(II,III) Carboxylate Clusters with a {Mn6O2} Core in Polymeric Structures
A new series of hexanuclear mixed-valent carboxylate coordination clusters of the type [Mn6O2(O2CR)10L4] (R = CMe3; CHMe2) featuring a {MnII4MnIII2(μ4-O)2} core of composition [Mn6O2(O2CCMe3)10(Me3CCO2H)3(EtOH)]•(Me3CCO2H) (1), [Mn6O2(O2CCMe3)10(Me3CCO2H)2 (EtOH)2]•2(EtOH) (2) and [Mn6O2(O2CCMe3)10(Me3CCO2H)2(MeOH)2]•2(MeOH)•H2O (3), and coordination polymers which incorporate such clusters, namely [Mn6O2(O2CCHMe2)10(pyz)(MeOH)2]n (4), {[Mn6O2(O2CCHMe2)10(pyz)1.5(H2O)]•0.5(H2O)}n (5), and [Mn6O2(O2CCMe3)10(HO2CCMe3)2(en)]n (6), have been synthesized (where pyz = pyrazine, en = ethyl nicotinate). The modification of the cluster surface by a diverse combination of capped or bridging ligands attached to peripheral MnII atoms results in discrete clusters with a closed hydrophobic exterior shell in 1 and 2, supramolecular chains built through hydrogen bonded solvent molecule clusters in 3, linear coordination polymers in 4 and 6 or a ladder-like coordination polymer in 5. The H-bonded coordination polymers 4 and 5 form supramolecular layers in crystals
Synthesis and absolute configuration assignment of 5-amino-1,3,5-triphenyl-pentane-1,3-diol stereoisomers
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