4‑Diazoisochroman-3-imines: A Class of Metal Carbene Precursors for the Synthesis of Isochromene Derivatives

4-Diazoisochroman-3-imines were investigated for their synthetic applications as a new class of metal carbene precursors. Under the catalysis from a Rh­(II) complex, this class of α-diazo imidates reacted with alkenes and conjugated dienes through a formal [2 + 1] (i.e., cyclopropanation) or [4 + 3] cycloaddition to furnish spiro­[cyclopropane-1,4′-isochroman]-3′-imines and tetrahydroisochromeno­[3,4-<i>b</i>] azepines, respectively. When Rh­(II)/AgOTf was used as cocatalyst, the formal [3 + 2] cycloaddition of 4-diazoisochroman-3-imines with terminal alkynes took place, leading to the synthesis of 2-aryl-3,5-dihydroisochromeno­[3,4-<i>b</i>]­pyrroles

Shape-Controlled CdS/ZnS Core/Shell Heterostructured Nanocrystals: Synthesis, Characterization, and Periodic DFT Calculations

CdS/ZnS core/shell heterostructured nanocrystals (NCs) with six monolayers (MLs) of ZnS shell on a zinc-blende CdS core were synthesized via successive ionic layer adsorption and reaction. By adjusting the growth temperature of the ZnS shell from 220 to 280 °C, the shape of CdS/ZnS NCs can be tuned to tetrapods, tetrahedra, and dots. Shell growth was confirmed to be uniform by X-ray diffraction, transmission electron microscopy, UV–vis absorption, and photoluminescence spectroscopy. Periodic density functional theory calculations were used to further study the growth mechanism of the differently shaped CdS/ZnS core/shell NCs. Our calculations revealed that the binding energy of model CH₃CH₂NH₂ molecules on the (110), (111), and (001) facets of the CdS core can determine which crystallographic facets are favored during the growth of the ZnS shell. The calculations provided insights into the effect of the interaction between the organic ligand and the facets of the CdS core on the shape engineering of CdS/ZnS core/shell NCs