4-Bromo-,'-di-phenyl-benzimidamide '-oxide.

The title compound, CHBrNO, crystallizes with two similar mol-ecules in the asymmetric unit. The extended structure features dimers linked by pairs of N-H⋯O and C-H⋯O hydrogen bonds. The HNCNO moiety of the title compound shows delocalization over the N-C-N part, as evidenced by the similar C-N bond distances.

Refreshing the Legacy of Rudolf Nietzki: Benzene-1,2,4,5-tetramine and Related Compounds.

Like hydroquinones and quinones, aromatic compounds with multiple NH groups and the corresponding quinonediimines have the potential to serve as components of useful redox-active organic materials. Benzene-1,2,4,5-tetramine (BTA) and its oxidized form BTA-H offer a promising redox pair of this type, and the compounds have proven to be useful in many areas of chemistry. However, key aspects of their behavior have remained poorly studied, such as the nature of their protonated forms, their preferred molecular structures, their reactivity, and their organization in condensed phases.

Homomeric chains of intermolecular bonds scaffold octahedral germanium perovskites.

Perovskites with low ionic radii metal centres (for example, Ge perovskites) experience both geometrical constraints and a gain in electronic energy through distortion; for these reasons, synthetic attempts do not lead to octahedral [GeI] perovskites, but rather, these crystallize into polar non-perovskite structures. Here, inspired by the principles of supramolecular synthons, we report the assembly of an organic scaffold within perovskite structures with the goal of influencing the geometric arrangement and electronic configuration of the crystal, resulting in the suppression of the lone pair expression of Ge and templating the symmetric octahedra. We find that, to produce extended homomeric non-covalent bonding, the organic motif needs to possess self-complementary properties implemented using distinct donor and acceptor sites.

Seeking Rules Governing Mixed Molecular Crystallization.

Mixed crystals result when components of the structure are randomly replaced by analogues in ratios that can be varied continuously over certain ranges. Mixed crystals are useful because their properties can be adjusted by increments, simply by altering the ratio of components. Unfortunately, no clear rules exist to predict when two compounds are similar enough to form mixed crystals containing substantial amounts of both.

Diphenoquinhydrones and Related Hydrogen-Bonded Charge-Transfer Complexes.

Benzoquinone and hydroquinone cocrystallize to form quinhydrone, a 1:1 complex with a characteristic structure in which the components are positioned by hydrogen bonds and charge-transfer interactions. We have found that analogous diphenoquinhydrones can be made by combining 4,4'-diphenoquinones with the corresponding 4,4'-dihydroxybiphenyls. In addition, mixed diphenoquinhydrones can be assembled from components with different substituents, and mismatched quinhydrones can be made from benzoquinones and dihydroxybiphenyls.

Impact of physicochemical changes in milk ultrafiltration permeate concentrated by reverse osmosis on calcium phosphate precipitation.

This study aimed to characterize and compare the mechanisms of calcium phosphate precipitation in skimmed milk ultrafiltration permeate (MP) and MP preconcentrated by reverse osmosis (ROMP). The effects of different physicochemical parameters such as the pH (8.0), the heating time (60 or 120 min at 60 °C) and the seeding of samples with dicalcium phosphate (DCP) were tested.

S-Heptazine N-ligand based luminescent coordination materials: synthesis, structural and luminescent studies of lanthanide-cyamelurate networks.

Various series of lanthanide metal-organic networks denoted Ln- (Ln = La, Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), were synthesized under solvothermal conditions using potassium cyamelurate (K) and lanthanide nitrate salts. All obtained materials were fully characterized, and their crystal structures were solved by single-crystal X-ray diffraction. Four types of coordination modes were elucidated for the Ln- series with different Ln coordination geometries.

Diphenoquinones Redux.

Benzoquinones can undergo reversible reductions and are attractive candidates for use as active materials in green carbon-based batteries. Related compounds of potential utility include 4,4'-diphenoquinones, which have extended quinonoid structures with two carbonyl groups in different rings. Diphenoquinones are a poorly explored class of compounds, but a wide variety can be synthesized, isolated, crystallized, and fully characterized.

The Role of Hydrogen Bonds in Interactions between [PdCl] Dianions in Crystal.

[PdCl] dianions are oriented within a crystal in such a way that a Cl of one unit approaches the Pd of another from directly above. Quantum calculations find this interaction to be highly repulsive with a large positive interaction energy. The placement of neutral ligands in their vicinity reduces the repulsion, but the interaction remains highly endothermic.

Hydrogen Bond Patterns of Dipyridone and Bis(Hydroxypyridinium) Cations.

Dipyridonyl-substituted derivatives of benzene, pyridine, and pyrazine, respectively, were synthesized to examine the ability of 2-pyridone and its protonated species to direct the self-assembly by hydrogen bonding. Structural analysis by single-crystal X-ray diffraction (SCXRD) of and in trifluoroacetic acid demonstrated that salts are formed as a result of the transfer of protons from the acid to the base (organic species) to generate a bis(hydroxypyridinium) dication. However, if no proton transfer takes place like in the case of crystals of grown from DMSO/HO, the self-assembly is mainly directed by the typical (8) hydrogen bond motif of 2-pyridone.

Designing Tetraoxa[8]circulenes To Serve as Hosts and Sensors.

In -symmetric tetraoxa[8]circulenes, alternating fused benzene and furan rings form an octagonal array. These compounds are little known despite their novel properties, which include extended planar π-conjugation and a formally antiaromatic cyclooctatetraene core. Tetraoxa[8]circulenes can be formed by acid-induced cyclocondensations of suitable quinones, but existing methods often give very low yields.

Experimental and theoretical evidence of attractive interactions between dianions: [PdCl]⋯[PdCl].

Inspection of the arrangement of tetrachloridopalladate(II) centers in a crystalline solid places the Cl of one [PdCl] directly above the Pd center of its neighbor. A survey of the CSD provides 22 more examples of such MX⋯MX complexes, with M being a Group 10 metal and X = Cl, Br, or I. Quantum calculations attribute this arrangement to a π-hole bond wherein Cl lone pairs of one unit transfer charge to vacant orbitals above the Pd center of its neighbor.

Flexible and porous 2D layered structures based on mixed-linker metal-organic frameworks for gas sorption studies.

Layered structures of flexible mixed-linker metal-organic frameworks termed IRHs-(4 and 5) (IRH = Institut de Recherche sur l'Hydrogène) were synthesized by mixing cyclam, tetrakis(4-carboxyphenyl)benzene (TCPB), and copper and zinc metal salts respectively. The new materials characterized by single-crystal X-ray diffraction exhibited the features of HOFs and MOFs. Their structures are formed by coordination and hydrogen bonds that link metallocyclam (with Cu or Zn) and TCPB to a 2D sheet which is further packed to form a 3D structure with 1D microchannels.

A Rational Design of Microporous Nitrogen-Rich Lanthanide Metal-Organic Frameworks for CO/CH Separation.

Three new lanthanide metal-organic frameworks IRHs-() supported by cyamelurate linkers have been synthesized and structurally characterized. The incorporation of numerous heteroatoms (N and O) into the pore walls and the relatively small microchannels of these porous solids enhance bonding force of the host-guest interactions, thus promoting the adsorption of carbon dioxide (CO) over methane (CH). The nonpolar covalent bonds in methane also favor the less uptake due to the hydrophilic walls of these frameworks.

Phosphangulene: A Molecule for All Chemists.

Phosphangulene () is a hexacyclic triarylphosphine with a distinctive conical shape and other features that allow the compound to be viewed from diverse perspectives and to be embraced by chemists from different parts of the field as a molecule worthy of special attention. In recent work, phosphangulene and its derivatives have proven to be effective tools for probing general principles that govern molecular organization in solids. The phosphangulene family is particularly well-suited for these studies because systematic structural changes in the compounds are easy to introduce.

Amidine/Amidinate Cobalt Complexes: One-Pot Synthesis, Mechanism, and Photocatalytic Application for Hydrogen Production.

A new synthetic route was carried out via a one-pot reaction to prepare a novel series of amidine/amidinate cobalt complexes - by mixing ligand (6-pyridin-2-yl-[1,3,5]-triazine-2,4-diamine) with Co(II) in acetonitrile or benzonitrile. We observed that a change of solvent from methanol (used in complex , previously reported) to nitrile solvents (MeCN and PhCN) led to the incorporation of the amidine group, ultimately forming -. So far, this is a unique method reported to introduce amidine/amidinate groups into a pyridinyl-substituted diaminotriazine complex.

-Tri-aqua-(1,10-phenanthroline-κ ,')(sulfato-κ)cobalt(II): crystal structure, Hirshfeld surface analysis and computational study.

The Co atom in the title complex, [Co(SO)(CHN)(HO)] (or CHCoNOS), is octa-hedrally coordinated within a cis-NO donor set defined by the chelating N-donors of the 1,10-phenanthroline ligand, sulfate-O and three aqua-O atoms, the latter occupying an octa-hedral face. In the crystal, supra-molecular layers lying parallel to (110) are sustained by aqua-O-H⋯O(sulfate) hydrogen bonding. The layers stack along the -axis direction with the closest directional inter-action between them being a weak phenanthroline-C-H⋯O(sulfate) contact.

ROY Reclaims Its Crown: New Ways To Increase Polymorphic Diversity.

Chemical compounds that exist in multiple crystalline forms are said to exhibit polymorphism. Polymorphs have the same composition, but their structures and properties can vary markedly. In many fields, conditions for crystallizing compounds of interest are screened exhaustively to generate as many polymorphs as possible, from which the most advantageous form can be selected.

Modular Construction of Porous Hydrogen-Bonded Molecular Materials from Melams.

Ordered materials with predictable structures and properties can be made by a modular approach, using molecules designed to interact with neighbors and hold them in predetermined positions. Incorporating 4,6-diamino-1,3,5-triazin-2-yl (DAT) groups in modules is an effective way to direct assembly because each DAT group can form multiple N-H⋅⋅⋅N hydrogen bonds according to established patterns. We have found that modules with high densities of N(DAT) groups can be made by base-induced double triazinylations of readily available amines.

Controlling Molecular Organization by Using Phenyl Embraces of Multiple Trityl Groups.

Sixfold phenyl embraces are well-established aromatic interactions that are strong and directional. In addition, functional groups that are able to participate, such as triphenylmethyl (trityl), are easily incorporated in molecular structures. As a result, embraces offer a possible way to control molecular organization in materials.

Building Large Structures with Curved Aromatic Surfaces by Complexing Metals with Phosphangulene.

Phosphangulene () is a hexacyclic triarylphosphine with a distinctive conical shape and an electron-rich aromatic surface that is geometrically and electronically complementary to fullerenes such as C and C. As a result, suitable derivatives of phosphangulene can cocrystallize with fullerenes or even bind them in solution. Surprisingly, previous work has largely overlooked the potential of phosphangulene to form complexes with metals, which offers a simple way to create large molecular structures with curved aromatic surfaces.

Mimicking 2,2':6',2'':6'',2'''-quaterpyridine complexes for the light-driven hydrogen evolution reaction: synthesis, structural, thermal and physicochemical characterizations.

The synthetic difficulties associated with quaterpyridine (qtpy) complexes have limited their use in the formation of various metallosupramolecular architectures in spite of their diverse structural and physicochemical properties. Providing a new facile synthetic route to the synthesis of functionalised qtpy mimics, we herein report the synthesis of three novel -NH functionalized qtpy-like complexes 12-14 with the general formula M(CHN)(NO) (M = Co(ii), Ni(ii) and Cu(ii)) in high yield and purity. Characterization of these complexes has been done by single crystal X-ray diffraction (SCXRD), thermogravimetric analysis, UV-Vis, infrared, mass spectrometry and cyclic voltammetry.

Programmed Molecular Construction: Driving the Self-Assembly by Coordination and Hydrogen Bonds Using 6-(Pyridin-2-yl)-1,3,5-triazine-2,4-diamine with M(NO) Salts.

A new series of hydrogen-bonded metallotecton networks of the general formula [M()(NO)] were obtained from the reaction of 6-pyridin-2-yl-[1,3,5]-triazine-2,4-diamine with transition-metal ions [M: Co(II), Ni(II), Cu(II), and Zn(II)]. Their supramolecular networks and associated properties were characterized by single-crystal and powder X-ray diffraction, IR, solid-state UV-vis spectroscopy, and thermogravimetric analysis associated with differential scanning calorimetry. On the basis of standard patterns of coordination involving 2,2'-bipyridine and simple derivatives, compound binds transition-metal ions with predictable constitution and the diaminotriazinyl (DAT) groups serve orthogonally to ensure the intermetallotecton interactions by hydrogen bonding according to well-established motifs .