Fr Francium

New charged cyclometalated iridium(III) complexes [Ir(ppy)₂(L)](PF₆) [ppy = 2-phenylpyridine; L = bis(pyrazol-1-yl)methane (for 1); L = bis(3,5-dimethylpyrazol-1-yl)methane (for 2)] were synthesized and their electrochemical and photophysical properties studied. These complexes with non-π-electron-conjugated ancillary chelates exhibit significantly blueshifted emission relative to those of commonly used derivatives with NN ancillary ligands such as bipyridine or phenanthroline. Both X-ray and theoretical analysis based on time-dependent density functional theory (TD-DFT) reveal that the binding of Ir to the bis(pyrazol-1-yl)methane ancillary ligand is much weaker than that to the phenylpyridine main ligand; the effect is enhanced in the excited state. As a result, the ancillary ligand does not participate in low-energy excitations and triplet emission, and the electronic transitions are concentrated on the main chromophoric ligands. The blueshift feature is attributed to emission originating from the main cyclometalated ligands, in contrast to emitters with the NN chromophoric ancillary ligand. In addition, complex 2 exhibits a one order of magnitude higher non-radiative decay rate than complex 1, which is attributed to the steric hindrance of the methyl groups that leads to a more loosely bound ancillary ligand.

The bis(pyrazol-1-yl)methane ancillary ligand induces a blueshift in the emission of charged cyclometalated iridium(III) complexes. In addition, the nonradiative rate constant increases by one order of magnitude when the ligand is substituted with methyl groups, which induce some steric hindrance and lead to a more loosely bound ancillary ligand.

The preparation of the secondary phosphane (Ph){C₆H₃-2,6-(CH₂NMe₂)₂}PH (1), a potentially base-stabilized ligand, and the sterically protected carbaborane-based phosphane (o-CH₃C₂B₁₀H₁₀)₂PH (2) is reported. Reaction of Sn{N(SiMe₃)}₂ with 1 gives the diphosphastannylene [(Ph){(C₆H₃-2,6-CH₂NMe₂)₂}P]₂Sn (3) in high yield. In contrast, the room-temperature reaction of 2 with Sn{N(SiMe₂)}₂ does not proceed. By applying elevated temperatures, the heteroleptic amidophosphastannylene {(o-CH₃C₂B₁₀H₁₀)₂P}{(SiMe₃)₂N}Sn (4) was formed, instead of the expected diphosphastannylene {(o-CH₃C₂B₁₀H₁₀)₂P}₂Sn. The thermal decomposition of compounds 3 and 4 was also studied. The thermal decomposition of 3 produced the new phosphorus–phosphorus-bonded compound 5, an unprecedented 1,2-diphosphol-type molecule.

Synthesis of diphosphastannylene [(Ph){C₆H₃-2,6-(CH₂NMe₂)₂}P]₂Sn and heteroleptic amidophosphastannylene {(o-CH₃C₂B₁₀H₁₀)₂P}{(SiMe₃)₂N}Sn is reported. The thermal decomposition of [(Ph){C₆H₃-2,6-(CH₂NMe₂)₂}P]₂Sn produced an unprecedented 1,2-diphosphol-type molecule.

RSC, Cambridge 2011. 332 pp., hardcover £ 132.99.—ISBN 978-1-84973-174-4

By the use of knowledge gained through modeling of drug metabolism mediated by the cytochrome P450 2D6 and 3A4 isoforms, we constructed a 2D-based model for site-of-metabolism prediction for the cytochrome P450 2C9 isoform. The similarities and differences between the models for the 2C9 and 2D6 isoforms are discussed through structural knowledge from the X-ray crystal structures and trends in experimental data. The final model was validated on an independent test set, resulting in an area under the curve value of 0.92, and a site of metabolism was found among the top two ranked atoms for 77 % of the compounds.

Foreseeing the breakdown: We developed a ligand-based model for predicting the site of drug metabolism mediated by cytochrome P450 2C9. The model is compared with two commercial models for two data sets. Because this model is constructed from only three descriptors and does not require 3D structures or electronic calculations, it is extremely rapid.

The front cover picture shows a schematic representation of the coordination network and the temperature dependence of magnetization of a cyano-bridged V–Nb bimetal assembly, K_0.59V^II_1.59V^III_0.41[Nb^IV(CN)₈]·(SO₄)_0.50·6.9H₂O. This compound exhibits ferrimagnetism with a high Curie temperature (T_C) of 210�K. This temperature is the highest T_C value among those of octacyano-bridged bimetal assemblies. The Short Communication by S. Ohkoshi et al. on p. 2649 ff. demonstrates that the increase in the superexchange pathways of V^II–NC–Nb^IV contributes to the achievement of the high T_C value.

The back cover picture highlights the mechanical and optical properties of a hybrid silica-PHEMA coating on glass reinforced by using goethite nanorods in relation with the local structure at the interface. We demonstrate the possibility to finely tune the final mechanical properties by adjusting the coating silica content. In this hybrid nanocomposite, goethite particles exhibit interesting stress relaxation functions, which prevent crack formation in the films whilst reaching high silica content in the hybrid matrix. Details are discussed in the article by N. Chemin, C. Chanéac et al. on p. 2675 ff.