Population genetics, phylogenomics and hybrid speciation of Juglans in China determined from whole chloroplast genomes, transcriptomes, and genotyping-by-sequencing (GBS).

Genomic data are a powerful tool for elucidating the processes involved in the evolution and divergence of species. The speciation and phylogenetic relationships among Chinese Juglans remain unclear. Here, we used results from phylogenomic and population genetic analyses, transcriptomics, Genotyping-By-Sequencing (GBS), and whole chloroplast genomes (Cp genome) data to infer processes of lineage formation among the five native Chinese species of the walnut genus (Juglans, Juglandaceae), a widespread, economically important group. We found that the processes of isolation generated diversity during glaciations, but that the recent range expansion of J. regia, probably from multiple refugia, led to hybrid formation both within and between sections of the genus. In southern China, human dispersal of J. regia brought it into contact with J. sigillata, which we determined to be an ecotype of J. regia that is now maintained as a landrace. In northern China, walnut hybridized with a distinct lineage of J. mandshurica to form J. hopeiensis, a controversial taxon (considered threatened) that our data indicate is a horticultural variety. Comparisons among whole chloroplast genomes and nuclear transcriptome analyses provided conflicting evidence for the timing of the divergence of Chinese Juglans taxa. J. cathayensis and J. mandshurica are poorly differentiated based our genomic data. Reconstruction of Juglans evolutionary history indicate that episodes of climatic variation over the past 4.5 to 33.80 million years, associated with glacial advances and retreats and population isolation, have shaped Chinese walnut demography and evolution, even in the presence of gene flow and introgression.

A new supramolecular assembly based on triple-Dawson-type polyoxometalate and 3d-4f heterometallic cluster.

The introduction of hexavacant Dawson-type precursor K(12)[H(2)P(2)W(12)O(48)] x 24 H(2)O into a HOAc/NaOAc (OAc(-) = acetate) buffer system containing (NH(4))(2)[Ce(IV)(NO(3))(6)] and Mn(II)(OAc)(2) x 4 H(2)O led to the isolation of a new compound, Na(20)[Ce(IV)(3)Mn(IV)(2)O(6)(OAc)(6)(H(2)O)(9)](2)[Mn(III)(2)P(2)W(16)O(60)](3) x 21 H(2)O (1). Compound 1 contains unusual triple-Dawson-type polyoxoanions [Mn(III)(2)P(2)W(16)O(60)](3)(24-) and bipyramid-like 3d-4f heterometallic clusters [Ce(IV)(3)Mn(IV)(2)O(6)(OAc)(6)(H(2)O)(9)](2+), which are arranged in a 3-D supramolecular assembly with 1-D channels. The Na(+) cations and solvent water molecules reside in the channels. Crystal data for 1 are as follows: hexagonal, P6(3)/mcm (No. 193), a = 24.959(4) A, c = 26.923(5) A, gamma = 120 degrees, V = 14525(4) A(3), and Z = 2. The electrochemical and electrocatalytic properties of compound 1 have been investigated.

A new Ni12 cluster based on polyoxometalate ligands.

A new Ni(12) cluster based on polyoxometalate ligands [Ni(12)(OH)(9)WO(4)(W(7)O(26)(OH))(PW(9)O(34))(3)](25-) (1) has been assembled in aqueous solution containing [PW(9)O(34)](9-), WO(4)(2-), and NiCl(2) x 6 H(2)O. The Ni(12) core in 1 shows a unique three-petal flower-shaped structure composed of three Ni(4) cubane units. Magnetic investigation indicates the presence of dominantly ferromagnetic interactions within the Ni(12) core.

A Surfactant-Encapsulating Polyoxometalate Nanowire Assembly as a New Carrier for Nanoscale Noble-Metal Catalysts.

The loading of noble-metal nanoparticles (NMNPs) onto various carriers to obtain stable and highly efficient catalysts is currently an important strategy in the development of noble metal (NM)-based catalytic reactions and their applications. We herein report a nanowire supramolecular assembly constructed from the surfactant-encapsulating polyoxometalates (SEPs) CTAB-PW12 , which can act as new carriers for NMNPs. In this case, the Ag NPs are loaded onto the SEP nanowire assembly with a narrow size distribution from 5 to 20 nm in diameter; the average size is approximately 10 nm. The Ag NPs on the nanowire assemblies are well stabilized and the over agglomeration of Ag NPs is avoided owing to the existence of well-arranged polyoxometalate (POM) units in the SEP assembly and the hydrophobic surfactant on the surface of the nanowire assembly. Furthermore, the loading amount of the Ag NPs can be adjusted by controlling the concentration of the AgNO3 aqueous solution. The resultant Ag/CTAB-PW12 composite materials exhibit high activity and good stability for the catalytic reduction of 4-nitrophenol (4-NP) with NaBH4 in isopropanol/H2 O solution. The NMNPs-loaded SEP nanoassembly may represent a new composite catalyst system for application in NM-based catalysis.

Hybrid Coordination Networks Constructed from ɛ-Keggin-Type Polyoxometalates and Rigid Imidazole-Based Bridging Ligands as New Carriers for Noble-Metal Catalysts.

Three hybrid coordination networks that were constructed from ɛ-Keggin polyoxometalate building units and imidazole-based bridging ligands were prepared under hydrothermal conditions, that is, H[(Hbimb)2 (bimb){Zn4 PMo(V8) Mo(VI) 4O40}]⋅6 H2O(1), [Zn(Hbimbp)(bimbp)3 {Zn4 PMo(V8) Mo(VI) 4O40}]⋅DMF⋅3.5 H2O(2), and H[Zn2 (timb)2 (bimba)2 Cl2 {Zn4 PMo(V8) Mo(VI) 4O40}]⋅7 H2O(3) (bimb=1,4-bis(1-imidazolyl)benzene, bimbp=4,4'-bis(imidazolyl)biphenyl, timb=1,3,5-tris(1-imidazolyl)benzene, bimba=3,5-bis(1-imidazolyl)benzenamine). All three compounds were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. The mixed valence of the Mo centers was analyzed by XPS spectroscopy and bond-valence sum calculations. In all three compounds, the ɛ-Keggin polyoxometalate (POM) units acted as nodes that were connected by rigid imidazole-based bridging ligands to form hybrid coordination networks. In compound 1, 1D zigzag chains extended to form a 3D supramolecular architecture through intermolecular hydrogen-bonding interactions. Compound 2 consisted of 2D curved sheets, whilst compound 3 contained chiral 2D networks. Because of the intrinsic reducing properties of ɛ-Keggin POM species, noble-metal nanoparticles were loaded onto these POM-based coordination networks. Thus, compounds 1-3 were successfully loaded with Ag nanoparticles, and the corresponding composite materials exhibited high catalytic activities for the reduction of 4-nitrophenol.