Water incorporation into a micellar-lamellar phase (dodecyl maltoside-water)

Many alkylated sugars are surfactants, and show lamellar phases which prove to be identical to those of more conventional surfactants. Most, if not all, previous investigations focus on the behaviour of these compounds in pure form. Dodecyl maltoside shows the same lamellar phase as when dry, but on the addition of water the layer spacing expands, and on addition of more water, a hexagonal phase forms. The area per head group increases substantially with water addition, indicating that the water is incorporated into the layers, possibly at the head groups. We suggest that the hexagonal phase is the system's answer to the frustration caused by a large head group area compared with that of the tails.     

Total synthesis of (±)-atractylon and (±)-lindestrene

The total synthesis of the eudesmane furanosesquiterpenes (±)-atractylon (1) and (±)-lindestrene (2) is described. Both 1 and 2 were synthesized via the methyl xanthate intermediate (10).     

A reinvestigation of o-phenylenemercurials : IV. Adducts of perfluorotribenzo[b,e,b][1,4,7]trimercuronin and the crystal and molecular structure of its 1 : 1 4-phenylpyridine solvate

Perfluorotribenzo[b,e,h][1,4,7]trimercuronin forms adducts of 1 : 1, 1 : 2 and 1 : 3 stoicheiometry with a variety of polar organic molecules. The structure of the 1 : 1 adduct with 4-phenylpyridine was solved by X-ray methods to an R factor of 7.4% for 3528 observed reflections.     

The effect of relaxation and rumpling on the point ion potential at NaCl(001) surfaces

The effect of surface relaxation and rumpling on the potential in the vicinity of a (001) surface of the NaCI structure is calculated within the point-ion approximation. Zero order (the Madelung term), first, and second order kubic harmonics are considered, and it is shown that it may be necessary to go beyond simple Stark splitting to interpret the energies of cationic surface excitations.     

The use of electron loss data as unit impulse response function in deconvolution of electron spectra

A simple model is presented to investigate whether the electron backscatter spectrum measured at the energy of an Auger peak provides an adequate respo     

A decoupled rigid bender model for the anharmonic force field of octahedral molecules

The molecular vibrational Hamiltonian for an octahedral molecule is derived to fourth order, subject to the constraint that the bond lengths are held constant. By assuming that the force field for the bending motions is a points-on-a-sphere potential, the location of the first difference bands for the pure bending motions is calculated; mode couplings are neglected. With these results, systematic trends in the anharmonic shifts can be predicted for the complete family of metal-hexafluorides. The effects of mode couplings and the importance of these calculations for understanding the initial process in the multiphoton dissociation of SF₆ are briefly discussed.     

Exploring uncharted terrain in nature's structure space using capillary NMR spectroscopy: 13 steroids from 50 fireflies

Capillary NMR spectroscopy (CapNMR) was used to characterize 13 new cardenolides and related steroids from a severely mass-limited natural products sample derived from a rare firefly, Lucidota atra. These analyses were carried out on only partially purified samples, each containing 20-100 mug of up to three steroids. Compared to other NMR spectroscopic techniques, CapNMR provided an up to 3-fold gain in sensitivity while maintaining very high spectral quality, which was essential for the identification of the L. atra steroids. We show that CapNMR allows for routine 1H and 13C NMR spectroscopic characterization of small molecule samples containing as little as 40 nmol of material.