具有手性半导体的近统一对映体过量和光物质相互作用的中尺度螺旋的组装。,Science Advances

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具有手性半导体的近统一对映体过量和光物质相互作用的中尺度螺旋的组装。
Science Advances ( IF 11.7 ) Pub Date : 2017-Mar-01 , DOI: 10.1126/sciadv.1601159
Wenchun Feng ₁ , Ji-Young Kim ₂ , Xinzhi Wang ₁ , Heather A. Calcaterra ₁ , Zhibei Qu ₁ , Louisa Meshi ₃ , Nicholas A. Kotov _{1,

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Affiliation

具有纳米级和中观级手性几何形状的半导体为偏振光学，光催化和仿生提供了丰富的材料平台。与金属和有机光学材料不同，手性半导体的几何形状与其手性之间的关系仍然不明确。具有定义几何形状的半导体螺旋的手性合奏为理解半导体材料的几何参数和手性之间的复杂关系开辟了道路。我们表明，可以以绝对产量ca制备半导体螺旋与分散在甲醇中的半胱氨酸稳定的碲化镉纳米颗粒（CdTe NPs）相比，对映体过量（ee）为0.1％和98％或更高。自发发生化学过程的高ee归因于基于NP的热力学偏好的手性自分选，以便与具有相同惯性的NP组装在一起。同手性自组装螺旋的分散显示宽带可见和近红外（Vis-NIR）极化旋转，各向异性（g）因子接近0.01。计算出的圆二色性（CD）光谱准确地再现了实验CD光谱，并针对不同的几何参数提供了经过实验验证的光谱预测，从而可以从头开始整脊半导体材料的设计。与主要用作散射体的金属，陶瓷和聚合物螺旋不同，半导体螺旋的手性具有几乎相等的光吸收和散射贡献，这对于面向设备的场驱动光调制至关重要。将螺旋解构为一系列纳米棒为螺旋的光-物质相互作用和手性活动提供了一个简单的模型。这项研究为进一步发展基于偏振的光学器件向生物医学应用，电信和高光谱成像创建了框架。

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Assembly of mesoscale helices with near-unity enantiomeric excess and light-matter interactions for chiral semiconductors.

Semiconductors with chiral geometries at the nanoscale and mesoscale provide a rich materials platform for polarization optics, photocatalysis, and biomimetics. Unlike metallic and organic optical materials, the relationship between the geometry of chiral semiconductors and their chiroptical properties remains, however, vague. Homochiral ensembles of semiconductor helices with defined geometries open the road to understanding complex relationships between geometrical parameters and chiroptical properties of semiconductor materials. We show that semiconductor helices can be prepared with an absolute yield of ca 0.1% and an enantiomeric excess (e.e.) of 98% or above from cysteine-stabilized cadmium telluride nanoparticles (CdTe NPs) dispersed in methanol. This high e.e. for a spontaneously occurring chemical process is attributed to chiral self-sorting based on the thermodynamic preference of NPs to assemble with those of the same handedness. The dispersions of homochiral self-assembled helices display broadband visible and near-infrared (Vis-NIR) polarization rotation with anisotropy (g) factors approaching 0.01. Calculated circular dichroism (CD) spectra accurately reproduced experimental CD spectra and gave experimentally validated spectral predictions for different geometrical parameters enabling de novo design of chiroptical semiconductor materials. Unlike metallic, ceramic, and polymeric helices that serve predominantly as scatterers, chiroptical properties of semiconductor helices have nearly equal contribution of light absorption and scattering, which is essential for device-oriented, field-driven light modulation. Deconstruction of a helix into a series of nanorods provides a simple model for the light-matter interaction and chiroptical activity of helices. This study creates a framework for further development of polarization-based optics toward biomedical applications, telecommunications, and hyperspectral imaging.

更新日期：2017-03-26

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