The synthesis and X-ray structure of two diasteriomeric heptapeptides [Ac-Ala-Ala-Ala-(R/S)-Cage-Ala-Ala-Ala-NH2] with a trishomocubane amino acid as a beta-turn scaffold are reported. The amino acid was synthesized as a racemate and two diastereomeric peptides were obtained. The two peptides were separated by preparative high-pressure liquid chromatography and crystals suitable for X-ray analysis were grown for both diasteriomeric peptides. In general, both the peptides satisfy the criteria for beta-turn conformations. Five of the six Ala residues of both cage peptide crystals satisfy the criteria for 3(10)-helix characteristics and the cage amino acid residue satisfied the alpha-helix classification. These experimental results confirm previous theoretical studies in our laboratory which predicted that the cage moiety would be a strong/active beta-turn inducer.

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A method using comprehensive (2) DGC with flame ionisation detection was developed to quantify 17 low-molecular-weight oxygenates in three different matrices, namely water, oil and gas, using a single calibration. The method was required for the pilot-plant experiments of a chemical process unit. From an analytical perspective, the first task was to find a suitable analytical method with sufficient selectivity and sensitivity to analyse the selected oxygenates at low levels in the presence of high levels of hydrocarbons. The second was the accurate quantitation of oxygenates in the water, oil and gas fractions, using the same instrument and calibration. Both these requirements were met by using comprehensive (2) DGC in the inverse configuration and calibrating the detector with the number of moles injected versus response. The method was successfully applied for the characterisation of the reactor product stream of the chemical process unit and made it possible to determine the fate of the selected oxygenates after passing through the reactor. The development of the method and some of the results are described in this paper.

In the title compound, [Mo(C5H5)(CO)2(C3H9P)2]CF3SO3, the cationic complex displays a classical four-legged piano-stool square-pyramidal geometry with a trans configuration of the basal ligands around the Mo atom. The cyclo­penta­dienyl (Cp) ligand occupies the apical position of the piano-stool configuration. The average Mo—P bond length of the two trans PMe3 ligands is 2.474 (5) Å and the Mo—Cp centroid distance is 2.003 (2) Å.

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