Magnetism and plasmonic performance of mesoscopic hollow ceria spheres decorated with silver nanoparticles.

We investigate the role of interfaces and surfaces in the magnetic and surface enhanced Raman spectroscopy (SERS) properties of CeO2 hollow spheres decorated with Ag nanoparticles (H-CeO2@Ag). The composites, H-CeO2@Ag, were synthesized using a newly developed two-step process. The CeO2 hollow sphere diameter ranges from 100 nm to 2 μm and the grafted Ag nanoparticle (NP) size varies from 5 to 50 nm with a controllable coverage ratio.

The stereodivergent formation of 2,6- and 2,6--tetrahydropyrans: experimental and computational investigation of the mechanism of a thioester oxy-Michael cyclization.

The origins of the stereodivergence in the thioester oxy-Michael cyclization for the formation of 4-hydroxy-2,6-- or 2,6--substituted tetrahydropyran rings under different conditions was investigated both computationally and experimentally. Synthetic studies showed that the 4-hydroxyl group was essential for stereodivergence. When the 4-hydroxyl group was present, TBAF-mediated conditions gave the 2,6--tetrahydropyran and trifluoroacetic acid-mediated conditions gave the 2,6--tetrahydropyran.