Poly[μ‐aqua‐μ4‐naphthalene‐1,8‐dicarboxylato‐zinc(II)]

In the title complex, [Zn(C₁₂H₆O₄)(H₂O)]_n, a Zn^II polymer based on naphthalene‐1,8‐dicarboxylate (1,8‐nap), the Zn^II atoms adopt an elongated octahedral coordination geometry. A zigzag chain is formed by μ₂‐aqua ligands and μ₂‐carboxylate groups of the 1,8‐nap ligands. Adjacent parallel chains are further linked by 1,8‐nap ligands, forming a twisted two‐dimensional layer structure along the (100) plane.     

Rhodopsin reconstituted into a planar-supported lipid bilayer retains photoactivity after cross-linking polymerization of lipid monomers

Transmembrane proteins (TMPs), particularly ion channels and receptors, play key roles in transport and signal transduction. Many of these proteins are pharmacologically important and therefore targets for drug discovery. TMPs can be reconstituted in planar-supported lipid bilayers (PSLBs), which has led to development of TMP-based biosensors and biochips. However, PSLBs composed of natural lipids lack the high stability desired for many technological applications. One strategy is to use synthetic lipid monomers that can be polymerized to form robust bilayers. A key question is how lipid polymerization affects TMP structure and activity. In this study, we have examined the effects of UV polymerization of bis-Sorbylphosphatidylcholine (bis-SorbPC) on the photoactivation of reconstituted bovine rhodopsin (Rho), a model G-protein-coupled receptor. Plasmon-waveguide resonance spectroscopy (PWR) was used to compare the degree of Rho incorporation and activation in fluid and poly(lipid) PSLBs. The results show that reconstitution of Rho into a supported lipid bilayer composed only of bis-SorbPC, followed by photoinduced lipid cross-linking, does not measurably diminish protein function.     

Ferromagnetic ordering and metamagnetism in malonate bridged 3D diamond-like and honeycomb-like networks: [Cu(mal)(DMF)]n and [[Cu(mal)(0.5pyz)].H2O]n (mal = Malonate Dianion,DMF = N,N-dimethylformamide,pyz = Pyrazine)

Two three-dimensional (3D) malonate bridged networks, [Cu(mal)(DMF)](n) (1) and [[Cu(mal)(0.5pyz)].H(2)O](n) (2), have been synthesized in H(2)O-DMF solution. Compound 1 exhibits ferromagnetic ordering below 2.6 K (T(c)), and 2 displays a metamagnetic behavior below 3.2 K (T(N)).     

Synthesis and characterization of scandium silyl complexes of the type Cp*2ScSiHRR'. sigma-Bond metathesis reactions and catalytic dehydrogenative silation of hydrocarbons

The scandium dihydrosilyl complexes Cp*(2)ScSiH(2)R (R = Mes (4), Trip (5), SiPh(3) (6), Si(SiMe(3))(3) (7); Mes = 2,4,6-Me(3)C(6)H(2), Trip = 2,4,6-(i)()Pr(3)C(6)H(2)) and Cp*(2)ScSiH(SiMe(3))(2) (8) were synthesized by addition of the appropriate hydrosilane to Cp*(2)ScMe (1). Studies of these complexes in the context of hydrocarbon activation led to discovery of catalytic processes for the dehydrogenative silation of hydrocarbons (including methane, isobutene and cyclopropane) with Ph(2)SiH(2) via sigma-bond metathesis.     

Terephthalamide derivatives as mimetics of helical peptides: disruption of the Bcl-x(L)/Bak interaction

A series of Bcl-x(L)/Bak antagonists, based on a terephthalamide scaffold, was designed to mimic the alpha-helical region of the Bak peptide. These molecules showed favorable in vitro activities in disrupting the Bcl-x(L)/Bak BH3 domain complex (terephthalamides 9 and 26, K(i) = 0.78 +/- 0.07 and 1.85 +/- 0.32 microM, respectively). Extensive structure-affinity studies demonstrated a correlation between the ability of terephthalamide derivatives to disrupt Bcl-x(L)/Bak complex formation and the size of variable side chains on these molecules. Treatment of human HEK293 cells with the terephthalamide derivative 26 resulted in disruption of the Bcl-x(L)/Bax interaction in whole cells with an IC(50) of 35.0 microM. Computational docking simulations and NMR experiments suggested that the binding cleft for the BH3 domain of the Bak peptide on the surface of Bcl-x(L) is the target area for these synthetic inhibitors.     

Ion-pair formation observed in a pulsed-field ionization photoelectron spectroscopic study of HF

The pulsed-field ionization (PFI) photoelectron (PE) spectrum of HF has been recorded at the chemical dynamics beamline of the advanced light source over the photon energy range 15.9-16.5 eV using a time-of-flight selection scheme at a resolution of 0.6 meV. Rotationally-resolved structure in the HF+(X 2 pi 3/2, 1/2, v+ = 0, 1) band systems are assigned. The spectral appearance of these systems agrees with a previous VUV laser PFI-PE study. Importantly, extensive rotationally-resolved structure between these two vibrational band systems is also observed. This is attributed to ion-pair formation via Rydberg states converging on the v+ = 1 vibrational levels of the HF+(X 2 pi 3/2, 1/2) spin-orbit states. These Rydberg states are assigned to the 1 sigma+ part of the nd-complexes (sigma, pi, and delta). Ion-pair formation is observed in this study by the detection of F- ions. Some partially rotationally-resolved structure in a previously published threshold photoelectron spectrum is similarly attributed to ion-pair formation (F- detection) through a combination of the v+ = 17 level of the (A 2 sigma+) 3s sigma Rydberg state and the (X 2 pi 3/2, 1/2, v+ = 1) 7d Rydberg states. On the basis of the present study, an accurate experimental value for the dissociation energy of the ground state of HF has been obtained, D0(HF) = 5.8650(5) eV.     

Eight-vertex tetrametallic structures derived from cubanes: a close relationship between bisdisphenoidal metallaborane and organometallic clusters

The metallaborane Cp4Co4B4H4 and the organometallic cluster Cp4Fe4C4H4 (Cp = eta5-cyclopentadienyl) not only are isoelectronic but also exhibit completely analogous eight-vertex bisdisphenoidal structures. Such structures, as well as the tetracapped tetrahedral structure of the Cp4Fe4(mu3-CO)4 precursor to Cp4Fe4C4H4, can be derived from a cube by insertion of diagonals in each of the six faces. Furthermore, the formation of Cp4Fe4C4H4 from Cp4Fe4(mu3-CO)4 can be described as a double diamond-square-diamond process preserving D2d symmetry throughout the process.     

A facile three-step synthesis of (±)-crispine A via an acyliminium ion cyclisation

A high yielding cyclisation of the readily available N-(4,4-diethoxybutyl)-2-(3,4-dimethoxyphenyl)acetamide to 8,9-bis(methyloxy)-2,3,6,10b-tetrahydropyrrolo[2,1-a]isoquinolin-5(1H)-one is described. The latter can be reduced with either AlH₃ or BH₃ to (±)-crispine A in an overall yield of 55%.     

Structural Consequences of S → Se Substitution in some Symmetrical [M(S2CNR2)3] Complexes

The consequences of replacement of the symmetrically chelate ligands in [M(E₂CNR₂)₃] (E = S, Se) complexes of potential 32 symmetry by analogous mixed S,Se unsymmetrical chelates are explored for both small (M = Co) and large (M = In) metal atoms, and R = primary (Et) and secondary (ⁱPr) alkyl substituents by way of low‐temperature single crystal X‐ray studies of [(Co(SSeCNEt₂)₃] ([Co(Se₂CNEt₂)₃] also determined as datum), and [In(SSeCNR₂)₃], R = Et, ⁱPr. The structure of [(ⁱPr₂N·CS·Se)₂] is also recorded.     

In situ soft X-ray studies of ethylene oxidation mechanisms and intermediates on the Pt(111) surface

In situ studies of ethylene oxidation on Pt(111) have been performed using a powerful combination of fluorescence yield soft X-ray methods for temperatures up to 600 K and oxygen pressures up to 0.01 Torr. Absolute carbon coverages have been determined both in steady-state and dynamic catalytic conditions on the Pt(111) surface. Fluorescence yield near-edge spectroscopy (FYNES) and temperature-programmed fluorescence yield near-edge spectroscopy (TP-FYNES) experiments above the carbon K edge were used to identify the structure and bonding of the dominant surface species during oxidation. TP-FYNES experiments of preadsorbed ethylene coverages in oxygen pressures up to 0.01 Torr indicate a stable intermediate is formed over the 215-300 K temperature range. By comparing the intensity of the C-H sigma resonance at the magic angle with the intensity in the carbon continuum, the stoichiometry of this intermediate has been determined explicitly. Based on calibration with known C-H stoichiometries, the intermediate has a C(2)H(3) stoichiometry for oxygen pressures up to 0.01 Torr, indicating oxydehydrogenation occurs before skeletal oxidation. FYNES spectra at normal and glancing incidences were performed to characterize the structure and bonding of this intermediate. Using FYNES spectra of ethylene, ethylidyne, and acetylene as reference standard, this procedure indicates the oxidation intermediate is tri-sigma vinyl. Thus, oxidation of ethylene proceeds through a vinyl intermediate, with oxydehydrogenation preceding skeletal oxidation.