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Two enantiomeric pairs of menthol derivatives, the menthol ester with 10-undecynoic acid and the 2-tricyanovinyl-pyrrole derivative of the methoxy-menthol, have been synthesized and their pure enantiomers obtained. The X-ray crystal and molecular structure of the (+)-enantiomer of the latter compound is reported.

Infrared and vibrational circular dichroism intensities have been evaluated theoretically for trans-(1S,2S)-dideuteriooxirane, trans-(1S,2S)-dideuteriocyclopropane, (S)-propylene oxide, and trans-(1R,2R)-dimethylcyclopropane molecules, via electric and electromagnetic nuclear shielding tensors determined by random-phase approximation within the framework of 6-31 g, 6-31 g ** , 6-31 gext, an d6-31 gpol Gaussian basis sets

Silicon and silicon nitride surfaces have been successfully terminated with carboxylic acid monolayers and investigated by atomic force microscopy (AFM) and scanning near-field optical microscopy (SNOM). On clean Si surface, AFM showed topographical variations of 0.3-0.4 nm while for the clean Si3N4 surface the corrugation was around 3-4 nm. After material deposition, the corrugation increased in both samples with a value in topography of 1-2 nm for Si and 5-6 nm for Si3N4. The space distribution of specific chemical species was obtained by taking SNOM reflectivity at several infrared wavelengths corresponding to stretch absorption bands of the material. The SNOM images showed a constant contribution in the local reflectance, suggesting that the two surfaces were uniformly covered. (C) 2003 Elsevier B.V. All rights reserved.

Carboxylic acid terminated (–COOH) monolayers (ML) have been covalently anchored on the surface (S) of crystalline silicon (Si) and silicon nitride (Si3N4) by using wet-chemistry methods. Their concentration has been determined adopting a stepwise procedure with a fluorescent probe in solution. First, 7-amino-4-methylcoumarin (H2N–C10H7O2, AMC) is covalently bonded to the monolayer on the surface through an amidation reaction forming an amide-terminated surface monolayer, S–(CH2)n–CO–NH–C10H7O2, then the surface is intensely washed in order to remove any physisorbed species, finally AMC is detached from the surface via hydrolysis of the –CO–NH– bond and quantified by a fluorescence analysis in water solution. The yields of both the amidation and hydrolysis reactions have been evaluated. By this method, submonolayers ≤0.1 ± 0.03 ML can be determined. It has been possible to evaluate the different extent of surface functionalization changing the substrate between Si and Si3N4 and for Si changing the monolayer formation reaction: heat- (Δ) or light- (hν) promoted or via cathodic electrografting (CEG). It came out that submonolayers are formed in any case, Si3N4 is functionalized to a larger extent than Si on heating (0.52 vs. 0.15 ML) and Si is best functionalized via cathodic electrografting: Δ, 0.15; hν 0.20; CEG, 0.44 ML. Surface topography of some monolayers on Si and Si3N4 substrates was investigated by Atomic Force Microscopy (AFM). On clean Si, AFM showed topographical variations of 0.3–0.4 nm while for the clean Si3N4 the corrugation was around 3–4 nm. After functionalization the two surfaces were uniformly covered and the corrugation increased in both samples with a corrugation in topography of 1–2 nm for Si and 5–6 nm for Si3N4.

Nuclear electric and electromagnetic shieldings have been calculated for ethylene oxide and cyclopropane. These are respectively related to the atomic polar tensors (APT) and atomic axial tensors (AAT) used by IR and VCD spectroscopists. The rototranslational sum rules fulfilled by the nuclear shieldings are used to assess the quality of the theoretical values. Our results for the electromagnetic shieldings are compared with previously reported calculations.

The optimal catalyst for the oxidation of butane to maleic anhydride is believed to by γ-(VO) 2 P 2 O 7 1 formed by thermal treatment of VOHPO 4 0.5H 2 O at ca. 400°C 2 . The mechanism is topotactic, the change from face -shared to edge shared VOO 5 octahedra requiring no breaking of V-O-P bonds 2 . The last-mentioned is prepared from V 2 O 5 and excess H 3 PO 4 in EtOH 2 . A further product is obtainable from this reaction, (VOHPO 4 ) 2 2.5H 2 O EtOH, also a layered material but with an enlarged interlayer distance of 13.48 A 3 This “ethanol-pillared” material gives a calcination behaviour different than that of VOHP 4 0.5H 2 O. The XAS spectra of the freshly calcined products obtained along the TG curve (at 110, 230, 400, and 700° C) have been measured and analysed to cast further light on the topotacticity of precursors to V-O-P catalysts. Calcination at 700° C (Pt crucible) gave two distinct phases, one yellow and the other green; they were separated mechanically.

Optically pure Δ(–)[Cr(pd)3] and partly resolved [Ru(pd)3] with the Δ(+)isomer in excess are afforded by an asymmetric synthesis from the corresponding (+)-tartrate complex (pd = pentane-2,4-dionate). Complexes rac-[M(pd)3](M = CoIII, CrIII, RhIII, or RuIII) partition between diethyl (+)-tartrate and (–)-α-pinene with a partial resolution of the optical isomers, the Λ isomer being generally the more soluble in the ester layer. The optical isomers of [Rh(pd)3] have been obtained from the racemic complex through the optically enriched fractions provided by the differential partitioning.

The EXAFS spectra of Co2+- and Ni2+-exchanged zirconium phosphates (mainly the α-forms) have been measured using synchrotron radiation. The M—O bond distances obtained are correlated with geometries inferred from electronic spectra. It is confirmed that there are changes in site geometry with degree of loading and calcination temperature. There is also further support for the presence of distorted tetrahedral sites in the anhydrous layered α-forms.For all the materials, a second shell is visible between 2.4 and 2.87 A(non-phase-shift corrected) depending on the particular material; these are ascribed to M⋯P distances.The gross changes in these second-shell distances, the M—O bond distances and the inter-layer distances are combined to suggest sites for the metal ions. As for the Cu2+ analogues, the zirconium phosphate layers do not remain rigid after exchange and calcination, but slide (and, perhaps, twist) to accommodate the CO2+ or Ni2+.

The extended X-ray absorption fine structure spectra of powered [Cu(NH3)5][BF4]2 have been measured at room temperature and at 77 K using synchrotron radiation. Standard Fourier-transform and least-squares fitting methods {utilising [Cu(en)2][BF4]2(en = ethylenediamine) as a model complex for extracting amplitude and phase parameters for Cu–N bonds} demonstrate that in each case only a single shell is present about the metal ion, i.e. all five Cu–N bonds are of equal length.

Interaction of the low-spin species bis(2-methylimidazole)tetratolylmesoporphyrinatoiron(III)[(TTP)Fe(2-MeIm)2] with Cu(acac)2(Hacac = acetylacetone) in chloroform leads to the high-spin species (TTP)Fe–2-MeIm–Cu(acac)2; spectral evidence indicates that magnetic interaction· between the CuII and the FeIII is weak.