Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada.
ACS Nano. 2009 Dec 22;3(12):3832-8. doi: 10.1021/nn9009455.
CdS magic-sized nanocrystals (MSNs) exhibiting both band gap absorption and emission at 378 nm with a narrow bandwidth of approximately 9 nm and quantum yield (QY) of approximately 10% (total QY approximately 28%, in hexane) were synthesized via a one-pot noninjection approach. This CdS MSN ensemble is termed as Family 378. It has been acknowledged that magic-sized quantum dots (MSQDs) are single-sized, and only homogeneous broadening contributes to their bandwidth. The synthetic approach developed is ready and highly reproducible. The formation of the CdS MSQDs was carried out at elevated temperatures (such as 90-140 degrees C) for a few hours in a reaction flask containing bis(trimethylsilyl)sulfide ((TMS)(2)S) and Cd(OAc)(OA) in situ made from cadmium acetate dihydrate (Cd(OAc)(2).2H(2)O) and oleic acid (OA) in 1-octadecene (ODE). Low OA/Cd and high Cd/S feed molar ratios favor this formation, whose mechanism is proposed to be thermodynamically driven. (13)C solid-state cross-polarization magic-angle spinning (CP/MAS) nuclear magnetic resonance (NMR) demonstrates that the capping ligands are firmly attached to the nanocrystal surface via carboxylate groups. With the cross-polarization from (1)H of the alkyl chains to surface (113)Cd, (113)Cd NMR is able to distinguish the surface Cd (471 ppm) bonding to both -COO(-) and S and the bulk Cd (792 ppm) bonding to S only. DOSY-NMR was used to determine the size of Family 378 ( approximately 1.9 nm). The present study provides strategies for the rational design of various MSNs.
CdS 魔法尺寸纳米晶体（MSNs）在 378nm 处表现出带隙吸收和发射，带宽约为 9nm，量子产率（QY）约为 10%（总 QY 约为 28%，在正己烷中），通过一锅非注射方法合成。这种 CdS MSN 集合体称为 Family 378。人们已经认识到，魔法尺寸量子点（MSQDs）是单尺寸的，只有均匀展宽对其带宽有贡献。所开发的合成方法简单易行，高度重现。在反应烧瓶中，在升高的温度（例如 90-140°C）下进行几个小时的反应，反应物为 bis(trimethylsilyl)sulfide((TMS)(2)S)和 Cd(OAc)(OA)，Cd(OAc)(2).2H(2)O 和 oleic acid（OA）原位反应生成。1-十八烯（ODE）。低 OA/Cd 和高 Cd/S 进料摩尔比有利于这种形成，其机制被提出是由热力学驱动的。（13）C 固态交叉极化魔角旋转（CP/MAS）核磁共振（NMR）表明，封端配体通过羧酸盐基团牢固地附着在纳米晶体表面上。通过（1）H 到表面（113）Cd 的交叉极化，（113）Cd NMR 能够区分表面 Cd（471ppm）与-COO(-)和 S 键合以及体相 Cd（792ppm）仅与 S 键合。DOSY-NMR 用于确定 Family 378 的尺寸（约 1.9nm）。本研究为各种 MSNs 的合理设计提供了策略。
