A semi‐synthetic analog of the cembranoid sarcophine

The title mol­ecule, 2(R)‐[(1E,3E,7S,8S,11E,13R)‐13‐hydroxy‐4,8,12‐tri­methyl‐7,8‐epoxy­cyclo­tetradeca‐1,3,11‐trien‐1‐yl]­propane‐1,2‐diol, C₂₀H₃₂O₄, is a semi‐synthetic analog of sarcophine, the natural cembranoid of marine origin, isolated from the soft coral Sarcophyton glaucum. The conformation of the 14‐membered ring differs substantially from that of sarcophine. The two OH groups of the propane‐1,2‐diol moiety form an unusual weak intramolecular hydrogen bond with an O⋯O distance of 2.788 (2) Å, and the mol­ecules are linked into double chains by intermolecular hydrogen bonds with O⋯O distances of 2.772 (2) and 2.849 (2) Å.     

Solid-supported biomimetic membranes with tailored lipopolymer tethers

Stable lipid membranes with controlled substrate-membrane spacing can be prepared using well-defined lipopolymers as a tether. Based on the living cationic ring-opening polymerization of 2-methyl- or 2-ethyl-2-oxazoline, lipopolymers can be synthesized bearing a lipid head group as well as a silanol reactive coupling end group. Using a “grafting onto” procedure these polymers can form dense, brush like monolayers, whose layered structures can be obtained by x-ray reflectivity measurements. By transfer of a pre-organized monolayer that is followed by vesicle fusion, stable polymer supported lipid membranes can be prepared. The substrate-membrane spacing can be controlled via the degree of polymerization, while the lateral diffusion of lipids within the membrane depends on the density of polymer tethers. Preliminary experiments implied that the membrane with long (N = 40) polymer tethers could reside trans-membrane receptors homogeneously, suggesting a large potential of this strategy.     

Halocarbon and arene coordination of lithium(I) in (1‐anilino‐3‐phenyl­imino­propenyl)chloro(methyl)­aluminium bis{[tetrakis(pentafluoro­phenyl)­borato]­lithium} benzene solvate

The crystal structure of the title compound, [AlCl(CH₃)‐(C₁₅H₁₃N₂)]­[Li(C₂₄BF₂₀)]₂­·C₆H₆, is reported. The unusual coordination features of the lithium(I) cation, including Li‐atom coordination to six organohalogen atoms and the shortest Li—F(C) distances so far observed, are discussed.     

[Hydroxy­tris­(penta­fluoro­phenyl)­borato‐O][N‐iso­propyl‐2‐(iso­propyl­amino)­troponiminato‐N]­methyl­indium(III)

The title complex, [In(CH₃)(C₁₈HBF₁₅O)(C₁₃H₁₉N₂)], crystallizes as an ion pair linked by a μ‐hydro­xo bridge. There are two independent mol­ecules in the asymmetric unit that exhibit essentially identical metric parameters, but different conformations.     

Acoustical criteria for concert hall stages

A survey of values of the inversion index (II) in a number of concert halls reveals large variations. Extreme values occur for stages of obviously quite different properties.Recent investigations have concentrated on the energy balance between direct sound energy and early reflection energy for a number of concert hall stages.Some numerical results, together with the corresponding reflectograms, are commented upon.     

Über das Verhältnis der Theorie der Elementarlänge zur Quantentheorie. II

The idea put forward in I that also such algebras which do not fulfil the axiom of powerassociativity may allow in some cases physical interpretation, is illustrated by a mathematical model showing properties similar to the Cartesian coordinates of a particle.     

Temporary anions of the fluoroethylenes

Electron transmission spectroscopy is employed to measure the gas phase electron affinities of the fluoroethylenes. Fluorination is found to destabilize the π* anions with respect to that of ethylene. The role of bond length changes as well as inductive and resonance effects is examined.