This critical review will be of interest to the experts in porous solids (including catalysis), but also solid state chemists and physicists. It presents the state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their ‘design’, aiming at reaching very large pores. Their dynamic properties and the possibility of predicting their structure are described. The large tunability of the pore size leads to unprecedented properties and applications. They concern adsorption of species, storage and delivery and the physical properties of the dense phases. (323 references)

Hybrid porous solids: past, present, future

Relationships between the carbon-oxygen stretching frequencies of carboxylato complexes and the type of carboxylate coordination

Hydrogen bond strengths revealed by topological analyses of experimentally observed electron densities

Helicates as Versatile Supramolecular Complexes.

Tetrathiafulvalenes, oligoacenenes, and their buckminsterfullerene derivatives: the brick and mortar of organic electronics.

THE biological breakdown of haem proceeds through a series of intermediates of which the orange-yellow bile pigment, bilirubin, the chromophore responsible for coloration in the various forms of jaundice, is a key member. In the adult human, for example, erythrocytes have a lifetime of about 3 months and their destruction produces about 300 mg bilirubin each day1,2. Although there were some early doubts (arising from the possibility of a cyclisation between the CIS vinyl group and the oxygen function at C19)3, the gross chemical structure (Fig. 1) for bilirubin has been beyond reasonable dispute for many years4. There remain, however, considerable structural uncertainties with respect to (1) stereochemistry, the geometry around bridges 5 and 15 being unknown, and represented variously as E or Z in the current literature. (The two configurations, E and Z, have been recognised in a model pyrromethanone system, however, (see ref. 5 and Fig. 2)); (2) tautomerism, although spectroscopic evidence favours the lactam formula for rings A and D (shown in Fig. 1) over the lactim6–9; and (3) conformation, although several speculations, supported by spectroscopic evidence and model making, are available10–17. We report the X-ray analysis of bilirubin—the first such analysis of a naturally occurring linear tetrapyrrole—which shows that bilirubin has the Z configuration at the C4–C5 and C15–C16 bonds, and possesses in the crystal a ridge tile conformation with considerable intramolecular hydrogen bonding.

Structure of bilirubin

A Novel Open-Framework Cobalt Phosphate Containing a Tetrahedrally Coordinated Cobalt(II) Center: CoPO4 · 0.5 C2H10N2

Crystals of bilirubin are triclinic, space group P1 with cell dimensions a = 19439, b = 11707, c = 15500 A, †, α = 9719, β =10022, γ = 11820°, Z = 4 The structure was solved by direct methods incorporating information derived from reflexion quartets and by using a set of diffractometer data containing 1408 reflexions with F obs ≥ 3σ( F obs ) The structure was refined with bond-length constraints to a final R of 0125 by using a set of microdensitometer-measured photographic data containing 1323 unique observed reflexions Both data sets were collected from a matured crystal whose diffraction pattern had improved considerably during a period of several weeks Bilirubin is shown to have the Z configuration at both the C5 and C15 bridges The two independent molecules of bilirubin in the crystal structure have very similar ‘ridge tile’ conformations: rings (A + B) and rings (C + D) form two good planes with an interplanar angle of approximately 97° and the molecule is stabilized by six intramolecular hydrogen bonds There is no evidence for any intermolecular hydrogen bonding Observed bond lengths suggest that bilirubin can be regarded as a 2,29 - dipyrrolylmethane with conjugating substituents at the α positions When freshly prepared, most crystals of bilirubin have reflexions hkl ( h odd) diffuse: this observation is discussed in terms of the molecular conformation of bilirubin and the particular packing arrangement which these molecules adopt in the crystal structure

The structure of bilirubin

Electrical and Magnetic Properties and X-Ray Structure of a Highly Conductive 4:1 Complex of Tetracyanoquinodimethane and a Tetrathiafulvalene Derivative†

Synthesis and chemistry of the bis(trimethylsilyl)amido bis-tetrahydrofuranates of the group 2 metals magnesium, calcium, strontium and barium. X-ray crystal structures of Mg[N(SiMe3)2]2·2THF and related Mn[N(SiMe3)2]2·2THF

Michael B. Hursthouse

Papers

Structure of bilirubin

A Novel Open-Framework Cobalt Phosphate Containing a Tetrahedrally Coordinated Cobalt(II) Center: CoPO4 · 0.5 C2H10N2

The structure of bilirubin

Electrical and Magnetic Properties and X-Ray Structure of a Highly Conductive 4:1 Complex of Tetracyanoquinodimethane and a Tetrathiafulvalene Derivative†

Synthesis and chemistry of the bis(trimethylsilyl)amido bis-tetrahydrofuranates of the group 2 metals magnesium, calcium, strontium and barium. X-ray crystal structures of Mg[N(SiMe3)2]2·2THF and related Mn[N(SiMe3)2]2·2THF