Computational evaluation of metal pentazolate frameworks::Inorganic analogues of azolate metal-organic frameworks

We report a periodic density-functional theory evaluation of putative frameworks, including a topologically novel arhangelskite (arh) structure, based on the pentazolate ion, the ultimate all-nitrogen, inorganic member of the azolate series of aromatic 5-membered ring anions.</p

In situ monitoring and mechanism of the mechanochemical formation of a microporous MOF-74 framework

Mechanochemistry provides a rapid, efficient route to metal-organic framework Zn-MOF-74 directly from a metal oxide and without bulk solvent. In situ synchrotron X-ray diffraction monitoring of the reaction course reveals two new phases and an unusual step-wise process in which a close-packed intermediate reacts to form the open framework. The reaction can be performed on a gram scale to yield a highly porous material after activation

An I2 O1 Barium Framework Derived from an In-Situ Metal-Assisted Ligand Transformation

The use of 4,4’-[oxalylbis(azanediyl)]bis(2-hydroxybenzoic acid) (H6L1) in the Ba2+ chemistry has afforded a 3D polymer, namely [Ba(H2L2)(H2O)](n) (1), which is based on H2L22- anions derived by the in-situ metal-assisted transformation of H6L1. The neutral H4L2 [4-(carboxyformamido)-2-hydroxybenzoic acid] ligand was isolated from 1 and characterized by spectroscopic methods. Polymer 1 is based on edge and facesharing BaO10 polyhedra which create an inorganic layer pillared to the third dimension by the organic ligands and has been classified as an (IO1)-O-2 framework. The topological analysis of 1 provided an opportunity to introduce a method for the deconstruction of (IO1)-O-2 frameworks by adopting principles applied in the deconstruction of Metal-Organic-Frameworks (MOFs) with rod Secondary Building Units (SBUs). A detailed discussion and insights for the proper use of the (IOn)-O-m notation which finds application in describing the dimensionality in MOFs, is also provided

High-spin Ni(ii) clusters: triangles and planar tetranuclear complexes

The exploration of the NiX2/py(2)CO/Et3N ( X= F, Cl, Br, I; py(2)CO = di-2-pyridyl ketone; Et3N = triethylamine) reaction system led to the tetranuclear [Ni4Cl2py(2)C(OH)O(2)py(2)C(OMe)O(2)(MeOH)(2)]Cl-2 center dot 2Et(2)O (1 center dot 2Et(2)O) and [Ni4Br2py(2)C(OH)O(2)py(2)C(OMe)O(2)(MeOH)(2)]Br-2 center dot 2Et(2)O (2 center dot 2Et(2)O) and the trinuclear [Ni-3py(2)C(OMe)O(4)]I-2 center dot 2.5MeOH (3 center dot 2.6MeOH), [Ni-3py(2)C(OMe)O(4)](NO3)(0.65)I-1.35 center dot 2MeOH (4 center dot 2MeOH) and [Ni-3py(2)C(OMe)O(4)](SiF6)(0.8)F-0.4 center dot 3.5MeOH (5 center dot 3.5MeOH) aggregates. The presence of the intermediate size Cl- and Br- anions resulted in planar tetranuclear complexes with a dense hexagonal packing of cations and donor atoms (tetramolybdate topology) where the X-anions participate in the core acting as bridging ligands. The F- and I- anions do not favour the above arrangement resulting in triangular complexes with an isosceles topology. The magnetic properties of 1-3 have been studied by variable-temperature dc, variable-temperature and variable-field ac magnetic susceptibility techniques and magnetization measurements. All complexes are high-spin with ground states S = 4 for 1 and 2 and S = 3 for 3

Two-dimensional frameworks built from Single-Molecule Magnets

Fine tuning the Mn/salicylaldoxime/trimesic acid reaction conditions leads to the formation of a regular 2D net held together by dative bonds and to a non-regular 2D net stabilised by both dative and hydrogen bonds. Both networks are built from [Mn-6] Single-Molecule Magnets

Ab Initio Prediction of Metal-Organic Framework Structures

Metal-organic frameworks (MOFs) have emerged as highly versatile materials with applications in gas storage and separation, solar light energy harvesting and photocatalysis. The design of new MOFs, however, has been hampered by the lack of computational methods for ab initio crystal structure prediction, which could be used to direct experimental synthesis. Here we report the first ab intio method for MOF structure prediction, and test it against a diverse set of MOFs, with differences in topology, metal coordination geometry and ligand binding sites. In all cases our calculations produced structures which match experiment, proving the versatility of our procedure for MOF structure prediction. With our new methodology for ab initio structure prediction, current approaches to MOF design are set to change towards a more sustainable theory-driven materials development.<br /