Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.

The Chemistry and Applications of Metal-Organic Frameworks

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

J. Appl. Cryst.の発刊に際して

1. INTRODUCTION Among the classes of highly porous materials, metalÀorganic frameworks (MOFs) are unparalleled in their degree of tunability and structural diversity as well as their range of chemical and physical properties. MOFs are extended crystalline structures wherein metal cations or clusters of cations (\" nodes \") are connected by multitopic organic \" strut \" or \" linker \" ions or molecules. The variety of metal ions, organic linkers, and structural motifs affords an essentially infinite number of possible combinations. 1 Furthermore, the possibility for postsynthetic modification adds an additional dimension to the synthetic variability. 2 Coupled with the growing library of experimentally determined structures, the potential to computationally predict, with good accuracy, affinities of guests for host frameworks points to the prospect of routinely predesigning frameworks to deliver desired properties. 3,4 MOFs are often compared to zeolites for their large internal surface areas, extensive porosity, and high degree of crystallinity. Correspondingly, MOFs and zeolites have been utilized for many of the same applications

Metal–Organic Framework Materials as Chemical Sensors

Metal–Organic Frameworks for Separations

Imidazolium salts are common building blocks for functional materials and in the synthesis of N-heterocyclic carbene (NHC) as σ-donor ligands for stable metal complexes. The title salt, 1,3-bis­(4-hy­droxy­phen­yl)-1H-imidazol-3-ium chloride (IOH·Cl), C15H13N2O2+·Cl−, is a new imidazolium salt with a hy­droxy functionality. The synthesis of IOH·Cl was achieved in high yield via a two-step procedure involving a di­aza­butadiene precursor followed by ring closure using tri­methylchloro­silane and paraformaldehyde. The structure of IOH·Cl consists of a central planar imidazolium ring (r.m.s. deviation = 0.0015 A), with out-of-plane phenolic side arms. The dihedral angles between the 4-hy­droxy­phenyl substituents and the imidazole ring are 55.27 (7) and 48.85 (11)°. In the crystal, O—H⋯Cl hydrogen bonds connect the distal hy­droxy groups and Cl− anions in adjacent asymmetric units, one related by inversion (−x + 1, −y + 1, −z + 1) and one by the n-glide (x − {1\over 2}, −y + {1\over 2}, z − {1\over 2}), with donor–acceptor distances of 2.977 (2) and 3.0130 (18) A, respectively. The phenolic rings are each π–π stacked with their respective inversion-related [(−x + 1, −y + 1, −z + 1) and (−x, −y + 1, −z + 1)] counterparts, with inter­planar distances of 3.560 (3) and 3.778 (3) A. The only other noteworthy inter­molecular inter­action is an O⋯O (not hydrogen bonded) close contact of 2.999 (3) A between crystallographically different hy­droxy O atoms on translationally adjacent mol­ecules (x + 1, y, x + 1).

https://journals.iucr.org/e/issues/2019/09/00/su5504/su5504.pdf

Synthesis and crystal structure of 1,3-bis­(4-hy­droxy­phen­yl)-1H-imidazol-3-ium chloride

5′-Deoxy-5′-iodoguanosine (I) crystals deposited from mixtures of water and methanol grow as nonsolvated hybrids of conformational polymorphs (Ia, Ib) and as a mixed solvate (Ic). Some solvent-free crystals are purely Ia, while others have varying amounts of Ib epitaxially intergrown with Ia. In Ia and Ib the conformations differ primarily by torsion about the C4′–C5′ bond (guanosine numbering scheme), which dramatically affects the iodine atom position. Powder diffraction and reconstructed reciprocal-lattice-slice images had small peaks incompatible with Ia. Some solvent-free crystals required lattices for both Ia and Ib to index all observable reflections. Unit-cell dimensions for Ia and Ib suggest the potential for epitaxial intergrowth. Hydrogen-bond networks in Ia and Ib are essentially identical and result in double layers of molecules in the ab plane, with layers of iodine at the layer surfaces. The iodine layers of Ia and Ib are incompatible: in Ia adjacent iodine atom layers interdigitate slightl...

Epitaxially Intergrown Conformational Polymorphs and a Mixed Water/Methanol Solvate of 5′-Deoxy-5′-iodoguanosine

Through structural modification of 2-anilinonicotinic acid by isomerization, the ΔpKa between the carboxylic acid and pyridinium NH increased dramatically over the threshold to form zwitterions in the newly designed 4-anilinonicotinic acids. This in turn led to the formation of a hydrogen bond between carboxylate and pyridinium NH, and the absence of two commonly observed synthons, i.e., the acid–acid homosynthon and acid–pyridine heterosynthon. The new synthon has a stronger hydrogen bond than the acid–acid homosynthon and the acid–pyridine heterosynthon, as suggested by theoretical calculations. This, together with the much larger ΔpKa, explains its formation.

Zwitterion formation and subsequent carboxylate–pyridinium NH synthon generation through isomerization of 2-anilinonicotinic acid

Propagation de rayons X Cu Kα dans un tunnel rempli d'helium : dispositif associe a un detecteur de RX

Sean Parkin

Papers

Synthesis and crystal structure of 1,3-bis(4-hydroxyphenyl)-1H-imidazol-3-ium chloride

Epitaxially Intergrown Conformational Polymorphs and a Mixed Water/Methanol Solvate of 5′-Deoxy-5′-iodoguanosine

Zwitterion formation and subsequent carboxylate–pyridinium NH synthon generation through isomerization of 2-anilinonicotinic acid

A helium-flushed beam tunnel

A Functionalization of Pro-cata Positions of Pentacene

Sean Parkin

Papers

Synthesis and crystal structure of 1,3-bis­(4-hy­droxy­phen­yl)-1H-imidazol-3-ium chloride

Epitaxially Intergrown Conformational Polymorphs and a Mixed Water/Methanol Solvate of 5′-Deoxy-5′-iodoguanosine

Zwitterion formation and subsequent carboxylate–pyridinium NH synthon generation through isomerization of 2-anilinonicotinic acid

A helium-flushed beam tunnel

A Functionalization of Pro-cata Positions of Pentacene

Synthesis and crystal structure of 1,3-bis(4-hydroxyphenyl)-1H-imidazol-3-ium chloride