From molecules to crystal engineering: supramolecular isomerism and polymorphism in network solids.

The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

The Halogen Bond

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Metal–Organic Frameworks and Self-Assembled Supramolecular Coordination Complexes: Comparing and Contrasting the Design, Synthesis, and Functionality of Metal–Organic Materials

This critical review highlights supermolecular building blocks (SBBs) in the context of their impact upon the design, synthesis, and structure of metal–organic materials (MOMs). MOMs, also known as coordination polymers, hybrid inorganic–organic materials, and metal–organic frameworks, represent an emerging class of materials that have attracted the imagination of solid-state chemists because MOMs combine unprecedented levels of porosity with a range of other functional properties that occur through the metal moiety and/or the organic ligand. First generation MOMs exploited the geometry of metal ions or secondary building units (SBUs), small metal clusters that mimic polygons, for the generation of MOMs. In this critical review we examine the recent (<5 years) adoption of much larger scale metal–organic polyhedra (MOPs) as SBBs for the construction of MOMs by highlighting how the large size and high symmetry of such SBBs can afford improved control over the topology of the resulting MOM and a new level of scale to the resulting framework (204 references).

Design and synthesis of metal-organic frameworks using metal-organic polyhedra as supermolecular building blocks.

Recent advances in transition metal catalyzed oxidation of organic substrates with molecular oxygen.

Based on the extended Huckel molecular orbital calculations, the relation between the anisotropy of the band structure and the arrangement of the organic molecules is investigated for two organic donors, tetrathiafulvalene (TTF) and bis(ethylenedithio)tetrathiafulvalene (BEDT–TTF). The intermolecular overlaps of their HOMO are calculated while the intermolecular arrangements are varied. The maps of the overlaps thus obtained are then used to estimate the band-structure parameters of (TMTTF)2X and (BEDT–TTF)2ClO4(C2H3Cl3)0.5. The Fermi surface of (TMTTF)2X is quasi-one-dimensional and not closed. On the contrary, (BEDT–TTF)2ClO4(C2H3Cl3)0.5 is regarded as a two-dimensional semimetal.

The Intermolecular Interaction of Tetrathiafulvalene and Bis(ethylenedithio)tetrathiafulvalene in Organic Metals. Calculation of Orbital Overlaps and Models of Energy-band Structures

On the basis of the extended Huckel molecular orbital calculation, the intermolecular overlaps of the highest occupied molecular orbitals are calculated for α-(BEDT-TTF)2I3 reported by Bender et al., and for superconducting β-(BEDT-TTF)2I3 reported by Yagubskii et al. (BEDT-TTF: bis(ethylenedithio)tetrathiafulvalene). α-(BEDT-TTF)2I3 is a two-dimensional semimetal or a narrow gap semiconductor. β-(BEDT-TTF)2I3 is a two-dimensional metal which has an almost isotropic closed Fermi surface.

Band structures of two types of (bedt-ttf)2i3

The X-ray crystal structure analysis of a sulfur containing π-donor molecule, bis(ethylenedithio)tetrathiafulvalene, (BEDT-TTF) shows that the BEDT-TTF molecule is nonplanar and that the crystal is composed of pairs of BEDT-TTF.

The Crystal and Molecular Structures of Bis(ethylenedithio)tetrathiafulvalene

Low-temperature structural study of [(CH3)4N][Ni(dmit)2]2 suggested that the rotational freedom of methyl group seems to play an important role in the “metal-semimetal” transition. Superconducting transition was observed at 5 K (7 kbar).

The First Molecular Superconductor Based on π-Acceptor Molecules and Closed-Shell Cations, [(CH3)4N][Ni(dmit)2]2, Low-Temperature X-Ray Studies and Superconducting Transition

The crystal structure and the electrical resistivities of BEDT-TTF compounds are reported. The most prominent feature of the crystal structure is the side-by-side array of BEDT-TTF molecules. The steric effects of the ethylene groups prevent the infinite stacking of the molecules. The electrical properties and the change in the X-ray diffraction patterns of β-(BEDT-TTF)2PF6 suggest that β-(BEDT-TTF)2PF6 is a one-dimensional conductor along the transverse direction. A simple band calculation indicates that (BEDT-TTF)2Cl04(C2H3C13) 0.5 is a two-dimensional semimetal. (BEDT-TTF)3(C104)2 shows a metal-insulator transition at 170 K, which is consistent with the one-dimensional band structure of this compound.

Yukiyoshi Sasaki

Papers

The Intermolecular Interaction of Tetrathiafulvalene and Bis(ethylenedithio)tetrathiafulvalene in Organic Metals. Calculation of Orbital Overlaps and Models of Energy-band Structures

Band structures of two types of (bedt-ttf)2i3

The Crystal and Molecular Structures of Bis(ethylenedithio)tetrathiafulvalene

The First Molecular Superconductor Based on π-Acceptor Molecules and Closed-Shell Cations, [(CH3)4N][Ni(dmit)2]2, Low-Temperature X-Ray Studies and Superconducting Transition

Crystal Structures and Electrical Properties of BEDT-TTF Coeipounds