Quantum dots (QDs) are capable of controlling the emission and absorption wavelength due to the bandgap widening effect of nanometer-sized particles. Many efforts have been made to increase the efficiency of QDs by using a core/shell structure. However, the conventional method of creating the core followed by shelling has the disadvantage of repeated processing. In this study, we synthesize composition gradient quaternary ZnCdSSe QDs of high efficiency (quantum yield. =88.96%, full width at half maximum. =28.20. nm) through one-pot synthesis. The X-ray diffraction peak for the (111) plane in ZnCdSSe QDs was shifted 2.64 compared to that for pure CdSe. From Cs-corrected STEM-EDS line scan results, it can be seen that the center of the QDs consists for more than 40% of Cd, clearly showing that a CdSe-rich core was formed, while the amount of Zn increases significantly toward the outer area. In addition, by using thermodynamics simulation, we propose a mechanism for formation of the composition gradient in QDs using one-pot synthesis and how this can be achieved with other compositions. Finally, we confirmed the chemical composition gradient inside a single quantum dot and proposed the formation behavior thereof using results of the thermodynamics simulation. The results herein may provide a way to identify the one-pot synthesis mechanism for quantum dots of various other composition gradients. This method greatly simplifies the procedure for synthesizing composition gradient ZnCdSSe QDs.
(Matrix Presented) Catalytic enantioselective allylation with a chiral bisphosphoramide was applied to the synthesis of LY426965, a serotonin antagonist. The key step, addition of a 3,3-disubstituted allyltrichlorosilane to benzaldehyde, provided the adduct containing a stereogenic quaternary center with excellent diastereoselectivity and enantioselectivity.
Constructing Quaternary Stereogenic Centers Using …
The first total synthesis of racemic perophoramidine is described. The key step features the highly stereoselective introduction of the vicinial quaternary centers via base-promoted carbon−carbon bond formation between a 3-alkylindole and a 3-bromo-3-alkylindolin-2-one. This transformation presumably proceeds through a conjugate addition or Diels−Alder cycloaddition of the 3-alkylindole with a 3-alkylindol-2-one intermediate.
Higher amines have the prefix amino as a functional group
N2 - (Matrix Presented) Catalytic enantioselective allylation with a chiral bisphosphoramide was applied to the synthesis of LY426965, a serotonin antagonist. The key step, addition of a 3,3-disubstituted allyltrichlorosilane to benzaldehyde, provided the adduct containing a stereogenic quaternary center with excellent diastereoselectivity and enantioselectivity.
Synthesis of (-)-Tetrodotoxin - Organic chemistry
A new concise construction of -clerodane diterpenoids is reported in which oxacyclic and -hydronaphthalene fragments are coupled, and the critical C9-quaternary carbon stereocenter formed stereoselectively, by 1,6-addition of a tertiary cuprate or a tertiary carbon radical to β-vinylbutenolide. This strategy is specifically illustrated by total syntheses of (−)-solidagolactone (4), (−)-16-hydroxycleroda-3,13-dien-15,16-olide (5, PL3), and (−)-annonene (6).