A short synthesis of praziquantel

The synthesis of praziquantel ( 1 ), a potent anthelmintic agent, is reported. The synthesis requires five steps and proceeds in 16% yield.     

New silyl ether reagents for the absolute stereochemical determination of secondary alcohols

[reaction: see text] Herein we report a new set of silyl ether reagents for determining the enantiomeric purity and absolute stereochemistry of secondary alcohols. These derivatives are easily synthesized, provide straightforward spectroscopic results, and allow for facile recovery of the original chiral alcohol.     

Guiding and confining light in void nanostructure

We present a novel waveguide geometry for enhancing and confining light in a nanometer-wide low-index material. Light enhancement and confinement is caused by large discontinuity of the electric field at high-index-contrast interfaces. We show that by use of such a structure the field can be confined in a 50-nm-wide low-index region with a normalized intensity of 20 microm(-2). This intensity is approximately 20 times higher than what can be achieved in SiO2 with conventional rectangular waveguides.     

Experimental development of a petal resonator surface coil

A surface coil for MRI was designed and built based on the principles of the petal resonator proposed by Mansfield [J Phys D Appl Phys 21 (1988) 1643]. This resonator coil design was named the petal resonator surface (PERES) coil and is composed of an eight-petal coil array and a central circular coil. A minimum separation of three times the petal coil radius is necessary to significantly decrease the mutual inductance. An analytical function for the PERES Signal-to-noise ratio (SNR) is obtained based on the quasistatic method. Theoretical plots of SNR enhancement yielded 26% and 35% more SNR over the circular coil and phased-array coils. Imaging experiments were first performed using a spectroscopy phantom on a 1.5-T commercial imager. Subsequently, brain images of healthy volunteers were obtained. Clinical MR imager compatibility allows this resonator coil to be used with conventional pulse sequences and imaging protocols. This coil design offers a new alternative to existing surface coils because it significantly increases the SNR.     

Chemical Engineering of Photoactivity in Heterometallic Titanium–Organic Frameworks by Metal Doping

We report a new family of titanium–organic frameworks that enlarges the limited number of crystalline, porous materials available for this metal. They are chemically robust and can be prepared as single crystals at multi‐gram scale from multiple precursors. Their heterometallic structure enables engineering of their photoactivity by metal doping rather than by linker functionalization. Compared to other methodologies based on the post‐synthetic metallation of MOFs, our approach is well‐fitted for controlling the positioning of dopants at an atomic level to gain more precise control over the band‐gap and electronic properties of the porous solid. Changes in the band‐gap are also rationalized with computational modelling and experimentally confirmed by photocatalytic H₂ production.     

Controlled Heterometallic Composition in Linear Trinuclear [LnCeLn] Lanthanide Molecular Assemblies

The combination of two different β-diketone ligands facilitates the size-controlled assembly of pure heterometallic [LnLn′Ln] linear compounds thanks to two different coordination sites present in the molecular scaffold. [HoCeHo], [ErCeEr], and [YbCeYb] analogues are presented here and are characterized both in the solid state and in solution, demonstrating the selectivity of this unique method to produce heterometallic 4f molecular entities.