Department of Chemistry, University of Wyoming , Laramie, Wyoming 82071, United States.
Department of Chemistry and Biochemistry, Texas Christian University , Fort Worth, Texas 76129, United States.
ACS Nano. 2016 Mar 22;10(3):3809-15. doi: 10.1021/acsnano.6b00567. Epub 2016 Mar 7.
L-cysteine derivatives induce and modulate the optical activity of achiral cadmium selenide (CdSe) and cadmium sulfide (CdS) quantum dots (QDs). Remarkably, N-acetyl-L-cysteine-CdSe and L-homocysteine-CdSe as well as N-acetyl-L-cysteine-CdS and L-cysteine-CdS showed "mirror-image" circular dichroism (CD) spectra regardless of the diameter of the QDs. This is an example of the inversion of the CD signal of QDs by alteration of the ligand's structure, rather than inversion of the ligand's absolute configuration. Non-empirical quantum chemical simulations of the CD spectra were able to reproduce the experimentally observed sign patterns and demonstrate that the inversion of chirality originated from different binding arrangements of N-acetyl-L-cysteine and L-homocysteine-CdSe to the QD surface. These efforts may allow the prediction of the ligand-induced chiroptical activity of QDs by calculating the specific binding modes of the chiral capping ligands. Combined with the large pool of available chiral ligands, our work opens a robust approach to the rational design of chiral semiconducting nanomaterials.
L-半胱氨酸衍生物诱导并调节手性的碲化镉（CdSe）和硫化镉（CdS）量子点（QDs）的旋光活性。值得注意的是，N-乙酰-L-半胱氨酸-CdSe 和 L-同型半胱氨酸-CdSe 以及 N-乙酰-L-半胱氨酸-CdS 和 L-半胱氨酸-CdS 表现出“镜像”圆二色性（CD）光谱，而与 QD 的直径无关。这是通过改变配体结构而不是配体绝对构型来反转 QD 的 CD 信号的一个例子。CD 光谱的非经验量子化学模拟能够重现实验观察到的符号模式，并证明手性的反转源于 N-乙酰-L-半胱氨酸和 L-同型半胱氨酸-CdSe 与 QD 表面的不同结合排列。这些努力可能允许通过计算手性封端配体的特定结合模式来预测 QD 诱导的手性旋光活性。结合大量可用的手性配体，我们的工作为合理设计手性半导体纳米材料开辟了一种稳健的方法。
