Homopolar dihydrogen bonding in alkali-metal amidoboranes and its implications for hydrogen storage

The solid-state structures of LiNH(2)BH(3) and NaNH(2)BH(3) have been shown recently to exhibit intricate M(δ+)···(δ-)H-B and N-H(δ+)···(δ-)H-B interactions. However, closer inspection of these structures reveals additional homopolar H···H interactions, viz., B-H(δ-)···(δ-)H-B and N-H(δ+)···(δ+)H-N, which contribute to the relative stability of the extended structures of these crystalline materials. In addition, an NMR study of the isotopomer LiND(2)BH(3) shows that a significant quantity of H(2) is desorbed thermally along with HD, which can only arise from hydride-hydride interactions, either directly from B-H(δ-)···(δ-)H-B moieties or indirectly through the participation of Li-H intermediates.     

Evolution of packing parameters in the structural changes of silica mesoporous crystals: cage-type, 2D cylindrical, bicontinuous diamond and gyroid, and lamellar

Cage-type, two-dimensional (2D) cylindrical hexagonal (C), bicontinuous diamond (D), bicontinuous gyroid (G), and one-dimensional (1D) lamellar (L) structures of silica mesoporous crystals (SMCs) were obtained by using the anionic surfactant N-stearoyl-l-glutamic acid (C(18)GluA) as a template in the presence of the nonionic surfactant C(16)(EO)(10) (Brij-56). The mesostructures were controlled by the organic/inorganic interface curvature change induced by Brij-56. A synthesis-field diagram showed that the mesostructure changed in the sequence cage-type → C → intergrowth of C and D → intergrowth of C and G → D → G → L with increase of the amount of Brij-56. Mixed micelles were formed by the anionic and nonionic surfactants, the packing parameter g of which increased with increasing the addition amount of nonionic surfactant and the reaction temperature. The local g parameter was obtained from electron crystallography reconstruction results by calculating mean curvatures and Gaussian curvatures from the equi-electrostatic potential surface. The intergrowth of C and D and two kinds of intergrowth of C and G are also discussed.     

Ruthenium complexes of 1,4,7-trimethyl-1,4,7-triazacyclononane for atom and group transfer reactions

With support by macrocyclic tertiary amine ligand 1,4,7-trimethyl-1,4,7-triazacyclononane (Me₃tacn), a number of mononuclear metal–ligand multiple bonded complexes have been isolated. Starting with a brief summary of these complexes, the present review focuses on ruthenium-oxo and -imido complexes of Me₃tacn. A family of monooxoruthenium(IV) complexes [Ru^IV(Me₃tacn)O(N–N)]²⁺ (N–N = 2,2′-bipyridines) and a cis-dioxoruthenium(VI) complex cis-[Ru^VI(Me₃tacn)O₂(CF₃CO₂)]⁺ have been isolated, and the structures of [Ru^IV(Me₃tacn)O(bpy)](ClO₄)₂ (bpy = 2,2′-bipyridine) and cis-[Ru^VI(Me₃tacn)O₂(CF₃CO₂)]ClO₄ have been determined by X-ray crystallography. Oxidation of [Ru^III(Me₃tacn)(NHTs)₂(OH)] (Ts = p-toluenesulfonyl) with Ag⁺ and electrochemical oxidation of [Ru^III(Me₃tacn)(H₂L)](ClO₄)₂ (H₃L = α-(1-amino-1-methylethyl)-2-pyridinemethanol) are likely to generate ruthenium-imido complexes supported by Me₃tacn. DFT calculations on cis-[Ru^VI(Me₃tacn)O₂(CF₃CO₂)]⁺ and proposed ruthenium-imido complexes have been performed. Complexes [Ru^IV(Me₃tacn)O(N–N)]²⁺ are reactive toward alkene epoxidation, and cis-[Ru^VI(Me₃tacn)O₂(CF₃CO₂)]⁺ efficiently oxidizes various organic substrates including concerted [3+2] cycloaddition reactions with alkynes and alkenes to selectively afford α,β-diketones, cis-diols, or CC bond cleavage products. Related oxidation reactions catalyzed by ruthenium Me₃tacn complexes include epoxidation of alkenes, cis-dihydroxylation of alkenes, oxidation of alkanes, alcohols, aldehydes, and arenes, and oxidative cleavage of CC, CC, and C–C bonds, all of which exhibit high selectivity. Ruthenium Me₃tacn complexes are also active catalysts for amination of saturated C–H bonds.     

Bruceines K and L from the Ripe Fruits of Brucea javanica

Bruceine K ( 1 ), a pentacyclic C₂₀‐quassinoid bearing a unique 12,20‐epoxy moiety, and bruceine L ( 2 ), along with the ten known compounds (6S,7E)‐6,9,10‐trihydroxy‐ and (6S,7E)‐6,9‐dihydroxymegastigma‐4,7‐dien‐3‐one ( 3 and 4 , resp.), cleomiscosins A–C, luteoline, quercetine, bruceantinol, pinoresinol, and thevetiaflavone, were isolated from the ripe fruits of Brucea javanica. Bruceines K ( 1 ) and L ( 2 ) were determined to be (1β,2α,11β,12β,14ξ,15β)‐12,20‐epoxy‐1,2,11,13,14,15‐hexahydroxypicras‐3‐en‐16‐one and (1β,2α,11β,12β,15β)‐13,20‐epoxy‐1,2,11,12‐tetrahydroxy‐16‐oxo‐15‐(senecioyloxy)picras‐3‐en‐21‐oic acid methyl ester (senecioic acid=3‐methylbut‐2‐enoic acid), respectively, on the basis of NMR (¹H‐ and ¹³C‐NMR, DEPT, ¹H,¹H‐COSY, NOESY, HMQC, and HMBC) and ESI‐MS data. Among the known compounds, (6S,7E)‐6,9,10‐trihydroxy‐ and (6S,7E)‐6,9‐dihydroxymegastigma‐4,7‐dien‐3‐one ( 3 and 4 , resp.), cleomiscosin C, luteoline, quercetine, and thevetiaflavone were isolated for the first time from the Brucea plants.     

Nitric oxide-releasing ruthenium nanoparticles

Nitric oxide-releasing ruthenium nanoparticles were synthesized by the reaction of alkanethiolate-protected ruthenium nanoparticles with tert-butyl nitrite ((t)BuONO), and their water-soluble derivatives are able to deliver NO to proteins such as reduced myoglobin upon light irradiation in aqueous media.     

Practical manganese-catalysed highly enantioselective cis-dihydroxylation of electron-deficient alkenes and detection of a cis-dioxomanganese(V) intermediate by high resolution ESI-MS analysis

A practical protocol has been developed for asymmetric cis-dihydroxylation of electron-deficient alkenes with Oxone catalysed by a manganese complex bearing a chiral tetradentate N(4)-donor ligand affording cis-diols in up to 95% yield with up to 96% ee. Analysis of the reaction mixture by high resolution ESI-MS revealed the formation of a cis-dioxomanganese(V) intermediate.     

Orientation dependence for Br formation in the reaction of oriented OH radical with HBr molecule

The orientation dependence of Br-atom formation in the reaction of the oriented OH radical with the HBr molecule using the hexapole electrostatic field was studied. Experimental results for the orientation dependence in the reaction were analyzed using a Legendre polynomial fit. The results show two reactive sites. It was found that O-end attack is most favored for this reaction, and that H-end attack also shows a pronounced reactivity. The reactivity of the side-ways attack was found to be small. By comparing the results of the orientation dependence in the reaction with studies of inelastic collisions and theoretical calculations, two reaction pathways are proposed. Reaction by O-end attack is followed by a direct abstraction of the H-atom from the HBr molecule. The mechanism for H-end attack may have H-atom migration from HBr to form the water molecule.     

Supravital fluorometric apoptosis detection in a single mouse embryo using lab-on-a-chip

Detection of apoptosis is one of the main criteria of preimplantation embryo growth potential assessment. Recent developments in lab-on-a-chip techniques has led to apoptosis detection and monitoring on a single cell or embryo level. However, single embryo apoptosis detection without a change in embryo developmental competence and post-examination "recovery" still remains a challenge. In this paper we present a lab-on-a-chip, co-working with miniaturized optical instrumentation, which allows supravital examination of single embryos for the presence of apoptotic blastomers with full after lab-on-a-chip study "recovery" and maintenance of their further developmental capacity.     

Bis(5,7‐dimethyl‐8‐hydroxyquinolinato)platinum(II) Complex for Efficient Organic Heterojunction Solar Cells

Organic photovoltaic (OPV) cells using metal(II) (Pt, Pd, Cu, and Ni) chelates of 8‐hydroxyquinoline (Hq) or 5,7‐dimethyl‐8‐hydroxy‐quinoline (HMe₂q) as an electron donor were fabricated by vacuum deposition. The bis(5,7‐dimethyl‐8‐hydroxyquinolinato)platinum(II) [Pt(Me₂q)₂]‐based OPVs showed the best performance with an open voltage (V_OC) of 0.42 V, a short circuit current density (J_SC) of 14.8 mA cm^?2, and a maximum power conversion efficiency (η_P) of 2.4 %. The X‐ray single‐crystal structures together with the grazing incidence X‐ray diffraction (GIXRD) data of thin film samples reveal that the peripheral methyl substituent(s) and platinum(II) ion are essential for the high degree of film crystallinity resulting in improved performance of the as‐fabricated field‐effect transistors (FETs) and OPV cells.     

Organo‐ and Hydrogelators Based on Luminescent Monocationic Terpyridyl Platinum(II) Complexes with Biphenylacetylide Ligands

A series of phosphorescent terpyridyl platinum(II) complexes with ancillary biphenylacetylide ligands, namely, [(R₃tpy)PtC≡C(biphenyl)]X (R=tBu, H, or Et₂N; tpy=2,2′;6′,2′′‐terpyridyl; X is an anion) were synthesized and structurally characterized by various spectroscopic techniques and X‐ray diffraction methods. Despite a lack of long alkyl chain(s) or hydrogen‐bonding motif(s), complexes [(tpy)PtC≡C(biphenyl)]Cl and [(tBu₃tpy)PtC≡C(biphenyl)]X (X=Cl, ClO₄, PF₆, or BF₄) were found to gelate water and organic solvents, respectively. The self‐aggregation of these complexes in solutions and the resulting gels were investigated with variable‐temperature (VT) ¹H NMR spectroscopy, polarized optical microscopy, and absorption/emission spectroscopy. SEM micrographs on dry gels revealed entangled nanofibers with diameters of 20–40 nm and lengths of tens of micrometers. Powder X‐ray diffraction (PXRD) study revealed various degrees of crystallinity of these fibrillar nanostructures. The substituents on both the terpyridyl and acetylide ligands and counterion of these complexes play a profound but concerted role in tuning the intermolecular metal???metal and/or π–π interactions, and hence the gelation properties.