AuICl-bound N-heterocyclic carbene ligands form MII4(LAuCl)6 integrally gilded cages

The incorporation of an N-heterocyclic carbene (NHC) moiety into a self-assembled MII4L₆ cage framework required the NHC first to be metallated with gold(i). Bimetallic cages could then be constructed using zinc(ii) and cadmium(ii) templates, showing weak luminescence. The cages were destroyed by the addition of further gold(i) in the form of Au^I(2,4,6-trimethoxybenzonitrile)₂SbF₆, which caused the reversibly-formed cages to disassemble and controllably release the Au^I-NHC subcomponent into solution. This release in turn induced the growth of gold nanoparticles. The rate of dianiline release could be tuned by capsule design or through the addition of chemical stimuli, with different release profiles giving rise to different nanoparticle morphologies.     

Photoinduced 1,4-additions of indoles to enones

[reaction: see text] A photoinduced procedure for the 1,4-addition of indoles to enones is described. This reaction occurs with modest to excellent yield for cyclic and some acyclic enones. This reaction is experimentally simple, requiring only irradiation (UVA lamps, ca. 350 nm) of the reagents in a CH2Cl2 solution at room temperature, and avoids the necessity to use a Lewis acid. An important solvent effect was noticed, with CH2Cl2 and CHCl3 being the optimal solvents. Various substituents are tolerated on the indole moiety and an electronic trend was noticed, as electron-withdrawing groups can suppress this reaction. A mechanism involving single electron transfer between the enone triplet excited state and the indole is proposed and accounts for all experimental observations.     

Single-mode low-loss chalcogenide glass waveguides for the mid-infrared

We demonstrate the design, fabrication, and characterization of single-mode low-loss waveguides for mid-infrared (MIR) wavelengths. Planar waveguide structures were fabricated from multilayer thin films of arsenic-based chalcogenide glasses followed by the creation of channel waveguides by using the photodarkening effect. Propagation losses as low as 0.5 dB/cm were measured for a quantum cascade laser end-fire coupled into the waveguides. This is a first step toward the design and fabrication of integrated optical components for MIR applications.     

Inclusion of volatile guests by a tetrapedal host: structure and kinetics

The host compound tetra(3-hydroxy-3,3-diphenyl-2-propynyl)ethene, TET, forms inclusion compounds with acetone, dimethyl sulfoxide, dioxane and pyridine. All the structures were successfully solved in the triclinic space group P1[combining macron]. We found variable host : guest ratios for the acetone (TET.ACE, H : G = 1 : 4), dimethyl sulfoxide (TET.DMSO, H : G = 1 : 4) and pyridine compounds (TET.PYR, H : G = 1 : 5). Solutions of the host compound and dioxane formed TET.2DIOX, H : G = 1 : 2 when left to crystallise at room temperature, whereas TET.4DIOX, H : G = 1 : 4 was formed during crystal growth at low temperature. We have correlated the structures with their thermal stabilities and kinetics of desolvation.     

Modified London model for the determination of λ and ζ in a high κ superconductor

We present a modified London model suggested by Brandt [1–3] which introduces a finite vortex core size appropriate for isotropic superconductors in which the average internal field is less than approximately (1/4)H _c2. TheSR lineshape resulting from this model possesses a distinctive shape due to the magnetic penetration depth and the vortex core diameter (approximately equal to twice the coherence length ). However, for a given lineshape, there is a large range of values of and which produce nearly the same lineshape. Lineshape smearing caused by disorder in the vortex lattice increases uncertainty in values for and . If well-determined values of either (T) or (T) are not available from another technique, both of them can be determined bySR measurements alone if runs in more than one applied field at the same temperature are fit with and as shared parameters. We also present our method of estimating the degree of disorder in the vortex lattice.