Kinetic resolution of racemic pyrrolidine-2,5-diones using chiral oxazaborolidine catalysts

Kinetic resolution of racemic C-3 substituted pyrrolidine-2,5-diones has been achieved for the first time using highly efficient oxazaborolidine catalysts derived from cis-1-amino-indan-2-ol.     

On the analysis of a kind of nonlinear Sobolev equation through locally applied pseudo‐spectral meshfree radial point interpolation

In this study, we develop an approximate formulation for two‐dimensional nonlinear Sobolev problems by focusing on pseudospectral meshless radial point interpolation (PSMRPI) which is a kind of locally applied radial basis function interpolation and truthfully a meshless approach. In the PSMRPI method, the nodal points do not need to be regularly distributed and can even be quite arbitrary. It is easy to have high order derivatives of unknowns in terms of the values at nodal points by constructing operational matrices. The convergence and stability of the technique in some sense are studied via some examples to show the validity and trustworthiness of the PSMRPI technique.     

The effect of ethynyl substitution and cyclopenta fusion on the ultraviolet absorption spectra of polycyclic aromatic hydrocarbons

We have examined the UV spectra of six newly-synthesized ethynyl-PAH (1-ethynylnaphthalene, 5-ethynylacenaphthylene, 1-ethynylanthracene, 9-ethynylphenanthrene, 3-ethynylfluoranthene, and 1-ethynylpyrene) and five corresponding CP-PAH (acenaphthylene, aceanthrylene, acephenanthrylene, cyclopenta[cd]fluoranthene, and cyclopenta[cd]pyrene) and have found the following systematic behavior: ethynyl-substitution results in average bathochromic shifts of 5 nm for the lower-wavelength beta- and beta'-bands and of 18 nm for the higher-wavelength p-band, as well as an amplification of the p-band with respect to the beta-band; the addition of a peripheral cyclopenta ring results in average bathochromic shifts of 7 nm in the beta-band, 16 nm in the beta'-band, and 44 nm in the p-band, compared to the wavelengths in the corresponding unsubstituted PAH. The addition of a cyclopenta ring also decreases the resolution of vibrational fine structure in the cases where the fine structure is particularly intense in the spectrum of the unsubstituted PAH. The effects of ethynyl substitution on the UV spectra of PAH are sufficiently consistent that new ethynyl-PAH should be identifiable based on their UV spectra alone.     

Capillary electrophoresis for the analysis of small-molecule pharmaceuticals

This paper reviews the application of CE to the analysis of small-molecule pharmaceuticals. The areas of pharmaceutical analysis covered are enantiomer separation, the analysis of small molecules such as amino acids or drug counter-ions, pharmaceutical assay, determination of related substances and physicochemical measurements such as log P and pK(a) of compounds. The different electrophoretic modes available and their advantages for pharmaceutical analysis are described. Recent applications of CE for each subject area are tabulated with electrolyte details.     

High power (130 mW) 40 GHz 1.55 μm mode-locked distributed Bragg reflector lasers with integrated optical amplifiers

High output power 40 GHz 1.55 μm passively mode-locked surface-etched distributed Bragg reflector (DBR) lasers with monolithically integrated semiconductor optical amplifiers are reported. These are based on an optimized AlGaInAs/InP epitaxial structure with a three quantum well active layer and an optical trap layer. The device produces near transform limited Gaussian pulses with a pulse duration of 3.3 ps. An average output power during mode-locked operation of 130 mW was achieved with a corresponding peak power of >1 W.     

Novel polymers from atom transfer polymerisation mediated by copper(I) Schiff base complexes

The use of copper(I) Schiff base complex catalysed atom transfer polymerisation of methacrylates is described. The use of a range of functional and multi‐functional initiators enables the synthesis of a range of functional and star polymers to be prepared under undemanding synthetic conditions. End capping with silyl enol ethers allows for ω‐functional polymers. The combination of novel initiators, functional monomers and end capping allows an unprecedented array of macromolecular structures to be produced with limited need for protecting group chemistry.