Twenty-one zeolitic imidazolate metal-organic frameworks based on Zn connectors (ZIFs) are derived and compared to known imidazolate networks. Not-yet-synthesized zinc imidazolates are identified on the basis of DFT total energy scoring. The structure with lowest energy is not porous and represents an unusual structure type with zni topology. Total energy scoring indicates the lcs and pcb networks as reliable ZIF candidates. The intrinsic channel chirality of the lcs network makes this rare topology an attractive target for the synthetic effort. Among the porous ZIFs candidates, the sodalite type, sod, is also found.

A combination of topological rules and quantum chemical calculations has facilitated the development of a rational metal-organic framework (MOF) synthetic strategy using the tritopic benzene-1,3,5-tribenzoate (btb) linker and a neutral cross-linker 4,4'-bipyridine (bipy). A series of new compounds, namely [M(2)(bipy)](3)(btb)(4) (DUT-23(M), M = Zn, Co, Cu, Ni), [Cu(2)(bisqui)(0.5)](3)(btb)(4) (DUT-24, bisqui = diethyl (R,S)-4,4'-biquinoline-3,3'-dicarboxylate), [Cu(2)(py)(1.5)(H(2)O)(0.5)](3)(btb)(4) (DUT-33, py = pyridine), and [Cu(2)(H(2)O)(2)](3)(btb)(4) (DUT-34), with high specific surface areas and pore volumes (up to 2.03 m(3)  g(-1) for DUT-23(Co)) were synthesized. For DUT-23(Co), excess storage capacities were determined for methane (268 mg g(-1) at 100 bar and 298 K), hydrogen (74 mg g(-1) at 40 bar and 77 K), and n-butane (99 mg g(-1) at 293 K). DUT-34 is a non-cross-linked version of DUT-23 (non-interpenetrated pendant to MOF-14) that possesses open metal sites and can therefore be used as a catalyst. The accessibility of the pores in DUT-34 to potential substrate molecules was proven by liquid phase adsorption. By exchanging the N,N donor 4,4'-bipyridine with a substituted racemic biquinoline, DUT-24 was obtained. This opens a route to the synthesis of a chiral compound, which could be interesting for enantioselective separation.

Bimetallic NiFe nanoparticles supported on carbon nanotubes (CNTs) were prepared and evaluated for catalytic hydrodeoxygenation (HDO) of guaiacol, which is a model ligninderived compound. Appropriate combination of Ni and Fe demonstrated high activity and significantly enhanced selectivity to cyclohexane and phenol, whereas monometallic Ni and Fe catalysts displayed poor activities or selectivities. The tunable selectivity of guaiacol HDO was found to be dependent on Ni/Fe atomic ratios. Cyclohexane and phenol are major products over the Ni5Fe1/CNT and Ni1Fe5/CNT catalysts, respectively. Characterization results confirmed that NiFe alloys were formed and elicited synergistic effects on the HDO performance. The selectivity-switchable performance of NiFe/CNT may be due to the synergism between Ni domains, where H2 could be easily activated, and Fe domains, which exhibited strong oxophilicity. Deactivation was observed over the monometallic catalyst which may be ascribed to the agglomeration of active nanoparticles. Metallic size effect on the HDO reaction was further investigated using monometallic Ni/CNT, Fe/CNT and bimetallic NiFe/CNT catalysts.

We describe the correlated electronic structure of a prototype Fe-pnictide superconductor, SmO1−xFxFeAs, using LDA+DMFT. Strong, multi-orbital electronic correlations generate a lowenergy pseudogap in the undistorted phase, giving a bad, incoherent metal in qualitative agreement with observations. Very good semi-quantitative agreement with the experimental spectral functions is seen, and interpreted, within a correlated, multi-orbital picture. Our results show that Fe-pnictides should be understood as low-carrier density, incoherent metals, in resemblance to the underdoped cuprate superconductors. PACS numbers: 71.27.+a, 74.25.Jb, Discovery of high-T c superconductivity (HTSC) in the Fe-based pnictides [1] is the latest among a host of other, ill-understood phenomena in d-band oxides. HTSC in Fe-pnictides emerges upon doping a bad metal with spin density wave (SDW) order at q = (π, 0). Preliminary experiments indicate [2, 3] unconventional SC. Existent normal state data indicate a "bad metal" without Landau Fermi Liquid (FL) quasiparticles at low energy [1]. These observations in Fe-pnictides are reminiscent of cuprate SC. The small carrier density (giving rise to carrier pockets), along with Uemura scaling from µ-SR [4] similar to hole-doped cuprates strongly suggests a SC closer to the Bose condensed, rather than a BCS (ξ ≃ 1000a) limit.

Four novel sp 3 -carbon allotropes with 6, 8 and 16 atoms per primitive cell have been derived using a combination of metadynamics simulations and topological scan. A novel chiral orthorhombic phase oC16 (C2221) was found to be harder than monoclinic M-carbon and shows remarkable stability in the high pressure range. A second orthorhombic phase of Cmmm symmetry, by ∼0.028 eV/atom energetically lower than W-Carbon, can be formed from graphite at ∼9GPa. In general, the mechanical response under pressure was found to depend on the structure topology, which reflects the way rings are formed from an initial graphene layer stacking.

We report a rapid additive-free synthesis of nanocrystals (NCs) of RHO-type ZIF-71 () of composition [Zn(dcim)2] (dcim = 4,5-dichloroimidazolate) in 1-propanol as solvent at room temperature. NC- has a size of 30-60 nm and exhibits permanent microporosity with a surface area (SBET = 970 m(2) g(-1)) comparable to that of microcrystalline material. When kept under the mother solution NC- undergoes transformation into a novel SOD-type polymorph (), which in turn converts into known ZIF-72 () with lcs topology. It is shown that microcrystals (MCs) of can be favourably synthesised using 1-methylimidazole as a coordination modulator. NC- with size <200 nm was prepared using NC-ZIF-8 as a template with SOD topology in a solvent assisted ligand exchange-related process. DFT-assisted Rietveld analysis of powder XRD data revealed that novel polymorph possesses an unusual SOD framework conformation. was further characterised with regard to microporosity (SBET = 597 m(2) g(-1)) and thermal as well as chemical stability. DFT calculations were performed to search for further potentially existing but not-yet synthesised polymorphs in the [Zn(dcim)2] system.

Numerous experiments showed that on cold compression graphite transforms into a new superhard and transparent allotrope. Several structures with different topologies have been proposed for this phase. While experimental data are compatible with most of these models, the only way to solve this puzzle is to find which structure is kinetically easiest to form. Using state-of-the-art molecular-dynamics transition path sampling simulations, we investigate kinetic pathways of the pressure-induced transformation of graphite to various superhard candidate structures. Unlike hitherto applied methods for elucidating nature of superhard graphite, transition path sampling realistically models nucleation events necessary for physically meaningful transformation kinetics. We demonstrate that nucleation mechanism and kinetics lead to M-carbon as the final product. W-carbon, initially competitor to M-carbon, is ruled out by phase growth. Bct-C4 structure is not expected to be produced by cold compression due to less probable nucleation and higher barrier of formation.

The transformation of cadmium selenide from the wurtzite type (B4) structure to its high-pressure phase (rocksalt type structure, B1) is investigated by means of molecular dynamics simulations using a recently introduced transition path sampling approach. This allows a very detailed mechanistic analysis, which is not spoiled by driving the process kinetics by excessive pressure. Furthermore, our approach is free of predefining a model reaction coordinate and the “true” reaction coordinate is derived as a direct result from the simulations instead. Starting the calculation from mechanistically different transition paths, we are able to identify a single favored mechanism for the transformation. The phase transition occurs by nucleation of a slab and subsequent phase growth. The underlying mechanism is identified as a shearing of (110) layers. This layer shuffling may occur in two equivalent ways—parallel and antiparallel—which in average are observed to occur at equal probability