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Lipase was covalently attached to multiwalled carbon nanotubes (MWNTs). Structural changes of the lipase upon attachment onto MWNTs were analyzed through circular dichroism and FTIR spectroscopy. The conjugate was utilized for the resolution of a model compound (R,S)‐1‐phenyl ethanol, and the reaction medium was n‐heptane. The enzymatic resolutions were carried out at temperatures from 35 to 60°C. The results show that the lipase attached onto MWNTs has significantly affected the performance of the enzyme in terms of temperature dependence and resolution efficiency. The activity of MWNT–lipase was less temperature‐dependent compared with that of the native lipase. The resolution efficiency was much improved with MWNT–lipase. MWNT–lipase retained the selectivity of the native lipase for (R)‐1‐phenyl ethanol. The consecutive use of MWNT–lipase showed that MWNT–lipase had a good stability in the resolution of (R,S)‐1‐phenyl ethanol. © 2010 American Institute of Chemical Engineers AIChE J, 2010

The highly energetic molecule Al(4)H(6), with its distorted tetrahedral structure, was recently characterized via mass spectrometry and photoelectron spectroscopy investigations (Li, X.; et al. Science 2007, 315, 356). Here we present the preparation and structural investigation of the first analogous Al(4)R(6) cluster compound. In order to understand the bonding in this kind of Al(4) molecule, density functional theory and second-order Møller-Plesset perturbation theory calculations were performed. The results obtained are discussed in comparison with bonding in other Al(4) moieties, especially the aromatic bonding behavior in the dianionic planar Al(4)(2-) species (Li, X.; et al. Science 2001, 291, 859). Finally, on the basis of the results obtained for Al(4) species, a more general problem is discussed: the difference in bonding between Zintl ions and metalloid clusters.

Silicon filling: Silicon‐doped Al44 superatoms form a cubic‐primitive crystal lattice (see picture; • Al, • Si) in the cluster Si@Al56[N(dipp)SiMe3]12, which is prepared from a metastable AlCl solution and the silicon‐containing ligand N(dipp)SiMe3 (dipp=2,6‐iPr2C6H3). The central silicon atom has a strong influence on the structure and the bonding situation in the cluster.

Reaction of the protonic ether compound [H(OEt 2 ) 2 ]-[Al(OR F ) 4 ] (R F ϭ C(CF 3 ) 3 ) with AlCp 3 leads to the formation of the [AlCp 2 ] ϩ -cation, which is stabilized by the weakly coordinating [Al(OR F ) 4 ] Ϫ ion. Besides [AlCp 2 ] ϩ , the ion [AlCp 2 · 2Et 2 O] ϩ , which is stabilized by two ether molecules, is formed in an equilibrium reaction. The so far unknown molecular structure of [AlCp 2 ] ϩ and

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The preparation and X‐ray structure of Si@Al14R6 (R = Cp*, N(Dipp)SiMe3; Dipp = 2,6‐iPr2–C6H3) are described via the disproportionation and substitution reaction of a metastable AlCl solution. One silicon atom occupies the center of an Al8 cube. This central unit is stabilized through capping of six AlR moieties above the faces of the cube. These findings open the door for a reinvestigation of Si@Al14Cp*6 through MALDI, DFT and X‐ray investigations: Caused by the preparation procedure a small part of the Si@Al14Cp*6 clusters are partially oxidized by chlorine and one of the eight aluminum atoms of the cube is substituted by a Si atom: Thus, within the crystal about 1/3 of the SiAl14Cp*6 clusters are Si2Al13Cp*6Cl species causing a more unsymmetrical arrangement of all cluster species than those observed in crystalline SiAl14(N(Dipp)SiMe3)6. The serious problems during the solution of the crystal structure of Si@Al14Cp*6 caused by only slightly modified cluster species may be a strong hint at being careful with the interpretation of any nanoscale species: Even very small modifications (e.g. a single silicon atom i.e. neighbor element of aluminum containing only one more electron and proton substitutes one aluminum atom) cause drastical structural changes and consequently also different e.g. electric properties can be expected.

We present an 27 Al NMR study of the metal cluster compound Al 50 Cp* 12 which is composed of (identical) Al 50 clusters, each surrounded by a Cp* ligand shell, and arranged in a crystalline 3D array (here Cp* = pentamethylcyclopentadienyl = C 5 (CH 3 ) 5 ). The compound is found to be non-conducting, the nuclear spin-lattice relaxation in the temperature range 100-300 K being predominantly due to reorientational motions of the Cp* rings. These lead to a pronounced maximum in the relaxation rate at T $ 170 K, corresponding to an activation energy of about 850 K. Data for the related compound Al 4 Cp* 4 , containing very much smaller Al 4 clusters are also presented. A comparison is drawn with the quadrupolar relaxation recently observed for the non-conducting fraction of Ga 84 molecules in the metal cluster compound Ga 84 [N(SiMe 3 ) 2 ] 20 -Li 6 Br 2 (thf) 20 AE2toluene.