ÌÇÐÄVlog

The design of pore properties utilizing flexible motifs and functional groups is of importance to obtain porous coordination polymers with desirable functions. We have prepared a 3D pillared-layer coordination polymer, {[Cd-2(pzdc)(2)L(H2O)(2)]center dot 5(H2O)center dot(CH3CH2OH)}(n) (1, H(2)pzdc = 2,3-pyrazinedicarboxylic acid; L = 2,5-bis(2-hydroxyethoxy)-1,4-bis(4-pyridyl)benzene) showing (i) a rotatable pillar bearing ethylene glycol side chains acting as a molecular gate with locking/unlocking interactions triggered by guest inclusion between the side chains, (ii) framework flexibility with slippage of the layers, and (iii) coordinatively unsaturated metal centers as guest accessible sites through the removal of the water coligands. The framework clearly shows reversible single-crystal-to-single-crystal transformations in response to the removal and rebinding of guest molecules, the observation of these processes has provided fundamental clues to the understanding of the sorption profiles. The X-ray structures indicate that the 3D host framework is retained during the transformations, involving mainly rotation of the pillars and slippage of the layers. The structure of dried form 2, [Cd-2(pzdc)(2)L](n), has no void volume and no water coligands. Interestingly, the adsorption isotherm of water for 2 at 298 K exhibits three distinct steps coinciding with the framework functions. Compound 2 favors the uptake of CO2 (195 K) over N-2 (77 K) and O-2 (77 K). Above all, we report on a molecular gate with a rotational module exhibiting a locking/unlocking system which accounts for gate-opening type sorption profiles.

Two novel layered germanates, denoted as SU-22 and SU-23, have been synthesized hydro(solvo)thermally by using diethylenetriamine (DETA) and 1,7-diaminoheptane (DAHep) as structure directing agents (SDAs), respectively. Their structures were determined by single-crystal X-ray diffraction. Both structures are built from the same Ge-7 clusters which are 4-coordinated following a 4(4) topology with different modes of linkage. SU-23 is the first example of a different mode leading to the formation of 10-rings, instead of 8- and 12-rings observed in the ASU-20 compounds and SU-22. A third type of linkage is also proposed. The study of the hydrogen bonding interaction pattern is developed to provide insight into the formation of these different modes in relation with the size and geometry of the SDAs, as they have a significant effect on the rotation and arrangements of Ge7 clusters. SU-22, [C4N3H15](1.5)[Ge7O14X3]center dot H2O (X = OH or F), monoclinic, space group C2/c, a = 16.0583(8), b = 16.4484(10), c = 17.7788(8) angstrom, beta = 98.151(6)degrees, R1 = 0.0430, for 4248 reflections with I < 2 sigma(I). SU-23, [C7N2H19][C7N2H20][Ge7O14X3][GeO2](0.2)center dot 3H(2)O, monoclinic, space group P2(1)/n, a = 13.036(3), b = 9.4726(19), c = 30.814(6) angstrom, beta = 100.03(3)degrees, R1 = 0.0349 for 5741 reflections with I < 2 sigma(I).

The synthesis of crystalline molecular sieves with pore dimensions that fill the gap between microporous and mesoporous materials is a matter of fundamental and industrial interest(1-3). The preparation of zeolitic materials with extralarge pores and chiral frameworks would permit many new applications. Two important steps in this direction include the synthesis(4) of ITQ-33, a stable zeolite with 18 x 10 x 10 ring windows, and the synthesis(5) of SU-32, which has an intrinsically chiral zeolite structure and where each crystal exhibits only one handedness. Here we present a germanosilicate zeolite (ITQ-37) with extralarge 30-ring windows. Its structure was determined by combining selected area electron diffraction ( SAED) and powder X-ray diffraction (PXRD) in a charge-flipping algorithm(6). The framework follows the SrSi2 (srs) minimal net(7) and forms two unique cavities, each of which is connected to three other cavities to form a gyroidal channel system. These cavities comprise the enantiomorphous srs net of the framework. ITQ-37 is the first chiral zeolite with one single gyroidal channel. It has the lowest framework density (10.3 T atoms per 1,000 angstrom(3)) of all existing 4-coordinated crystalline oxide frameworks, and the pore volume of the corresponding silica polymorph would be 0.38 cm(3) g(-1).

This communication briefly reviews why network topology is an important tool (for understanding, comparing, communicating, designing, and solving crystal structures from powder diffraction data) and then discusses the terms of an IUPAC project dealing with various aspects of network topology. One is the ambiguity in node assignment, and this question is addressed in more detail. First, we define the most important approaches: the "all node" deconstruction considering all branch points of the linkers, the "single node" deconstruction considering only components mixed, and the ToposPro "standard representation" also considering linkers as one node but, if present, takes each metal atom as a separate node. These methods are applied to a number of metal organic framework structures (MOFs, although this is just one example of materials this method is applicable on), and it is concluded that the "all node" method potentially yields more information on the structure in question but cannot be recommended as the only way of reporting the network topology. In addition, several terms needing definitions are discussed.

We report a new open-framework silicogermanate SU-61 containing 26-ring channels with a low framework density. It can be seen as a crystalline analogue to the mesoporous silica MCM-41. The structure is built from the assembly of (Ge,Si)(10)(O,OH)(28) clusters. It is the first time that silicon has been successfully introduced in the Ge-10 cluster in significant amounts (-21% of the tetrahedral sites). Five- and six-coordinated Ge-10 clusters have previously been observed in other germanate compounds leading to either dense or open structures. In SU-61, the seven-coordinated clusters fall onto yet another underlying net, the osf net. SU-61, along with other Ge-10 based frameworks, shows the versatility of the germanate system to adopt defined topologies playing on the connectivity of the clusters following the principles of net decoration and scale chemistry.

The systematic exploration of the phase diagram of the GeO2-1,6-diaminohexane-water-pyridine-HF system has allowed the identification of specific roles of the HF, H2O contents, and HF/H2O ratio in the formation of Ge7X19 (Ge-7), Ge9X25-26 (Ge-9), and Ge10X28 (Ge-10) clusters (X = 0, OH, F). This work has led to the discovery of two novel structures with extra-large 18-membered rings accommodating 1,6-diaminohexane (DAH): SU-63, 11.5H(2)DAHI-[Ge7O14X3].2H(2)O, a layered germanate constructed from Ge-7 clusters with the Kagome topology, and SU-64, I 11H(2)DAHI[Ge9O18X4][Ge7O14X3](6).16H(2)O, a germanate built of two-dimensional slabs containing both Ge-7 and Ge-9 clusters (X = OH or F). We also put SU-64 in context with previously reported cluster germanate compounds with related topologies by means of a simple crystal deconstruction study.

The first highly enantioselective, direct organocatalytic conjugate addition of unmodified aldehydes to alkylidinemalonates is presented. The reaction gives access to P-formyl-substituted malonates and highly functionalized lactones with up to 14:1 dr and generally 94 to > 99% ee.

In many intermetallic structures, the atoms and bonds divide space into tilings by tetrahedra. The well-known Frank-Kasper phases are examples. The dual tilings divide space into a tiling by polyhedra that is topologically a foam. The number of faces of the dual polyhedron corresponds to the atom coordination number in the direct structure, and face sharing by adjacent polyhedra corresponds to bonds in the direct structure. A number of commonly occurring intermetallic crystal structures are shown as their duals. A major advantage of this alternative mode of depiction is that coordination of all of the atoms can be seen simultaneously.

In this contribution, we present a coordination framework built from a novel (Zn(4)O)(O(2)C)(6) metaprismatic unit showing the interpenetration of a pair of enantiomorphic lcy nets that exhibits commensurate sorption properties.

A highly enantioselective organocatalytic one-pot synthesis of nitro-, formyl-, and ester-functionalized cyclopentanes with four stereocenters is presented. The cyclopentanes were formed as a predominant diasteroisomer and isolated in high yields with 97-99% ee.

Porosity and chirality are two of the most important properties for materials in the chemical and pharmaceutical industry. Inorganic microporous materials such as zeolites have been widely used in ion-exchange, selective sorption/separation and catalytic processes. The pore size and shape in zeolites play important roles for specific applications(1-3). Chiral inorganic microporous materials are particularly desirable with respect to their possible use in enantioselective sorption, separation and catalysis(4). At present, among the 179 zeolite framework types reported, only three exhibit chiral frameworks(5-7). Synthesizing enantiopure, porous tetrahedral framework structures represents a great challenge for chemists. Here, we report the silicogermanates SU-32 (polymorph A), SU-15 (polymorph B) (SU, Stockholm University) and a hypothetical polymorph C, all built by different stacking of a novel building layer. Whereas polymorphs B and C are achiral, each crystal of polymorph A exhibits only one hand and has an intrinsically chiral zeolite structure. SU-15 and SU-32 are thermally stable on calcination.

A new synthetic approach to prepare flexible porous coordination polymers (PCPs) by the use of soft secondary building units (SBUs) which can undergo multiple reversible metal-ligand bonds breaking is reported. We have prepared a zinc paddle-wheel-based two-fold interpenetrated PCP, {[Zn-2(tp)(2)(L-2)]center dot 2.5DMF center dot 0.5water}(n) (2a, H(2)tp = terephthanlic acid; L-2 = 2,3-difluoro-1,4-bis(4-pyridyl)benzene), showing dynamic structural transformations upon the removal and rebinding of guest molecules. The X-ray structures at different degrees of desolvation indicate the highly flexible nature of the framework. The framework deformations involve slippage of the layers and movement of the two interpenetrated frameworks with respect to each other. Interestingly, the coordination geometry of a zinc paddle-wheel unit (one of the popular SBUs) is considerably changed by bond breaking between zinc and oxygen atoms during the drying process. Two zinc atoms in the dried form 24 reside in a distorted tetrahedral geometry. Compound 24 has no void volume and favors the uptake of O-2 over Ar and N-2 at 77 K The 02 and Ar adsorption isotherms of 24 show gate-opening-type adsorption behaviors corroborating the structure determination. The CO2 adsorption isotherm at 195 K exhibits multiple steps originating from the flexibility of the framework The structural transformations of the zinc dusters in the framework upon sorption of guest molecules are also characterized by Raman spectroscopy in which the characteristic bands corresponding to v(sym) (COO-) vibration were used.

Symmetrical embeddings are given for multiply intergrown sets of some commonly occurring nets such as dia (diamond), qtz (quartz), pcu (net of primitive cubic lattice) and srs (labyrinth net of the G minimal surface). Data are also given for all known pairs of nets which have edge-transitive self-dual tilings. Examples are given for symmetrical polycatenation of the 2-periodic nets sql (square lattice) and hcb (honeycomb). The idea that the rings that are the faces of natural tilings form a complete basis set (essential rings) is explored and patterns of catenation of such rings described. (C) 2015 International Union of Crystallography

A series of open-framework germanates, alumino- and silico-germanates were synthesized (denoted as SU-n). Most of them were built from a few types of inorganic clusters containing a well-defined number of polyhedra: Ge(3)O(9) (4=1), Ge(4)O(16) (D4R) and larger clusters including 7, 9 and 10 Ge atoms (named Ge(7), Ge(9), Ge(10) clusters, respectively). Different arrangements and combinations of these clusters resulted in different open-framework structures including several novel zeolite frameworks. Here, we examine the different underlying nets and tilings observed in germanate-based compounds synthesized by our group and others.