Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States.
Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States.
J Phys Chem Lett. 2022 Feb 17;13(6):1416-1423. doi: 10.1021/acs.jpclett.1c03825. Epub 2022 Feb 4.
Semiconductor nanocrystals (NCs) have emerged as promising photocatalysts. However, NCs are often functionalized with complex ligand shells that contain not only charge acceptors but also other "spectator ligands" that control NC solubility and affinity for target reactants. Here, we show that spectator ligands are not passive observers of photoinduced charge transfer but rather play an active role in this process. We find the rate of electron transfer from quantum-confined PbS NCs to perylenediimide acceptors can be varied by over a factor of 4 simply by coordinating cinnamate ligands with distinct dipole moments to NC surfaces. Theoretical calculations indicate this rate variation stems from both ligand-induced changes in the free energy for charge transfer and electrostatic interactions that alter perylenediimide electron acceptor orientation on NC surfaces. Our work shows NC-to-molecule charge transfer can be fine-tuned through ligand shell design, giving researchers an additional handle for enhancing NC photocatalysis.
半导体纳米晶体（NCs）已经成为很有前途的光催化剂。然而，NCs 通常功能化有复杂的配体壳，不仅含有受体，还含有其他“旁观者配体”，控制 NC 的溶解性和对目标反应物的亲和力。在这里，我们表明旁观者配体并不是光诱导电荷转移的被动观察者，而是在这个过程中扮演着积极的角色。我们发现，通过用具有不同偶极矩的肉桂酸配体配位到 NC 表面，可以将量子限制的 PbS NCs 到苝二酰亚胺受体的电子转移速率变化超过 4 倍。理论计算表明，这种速率变化源于电荷转移的自由能和静电相互作用的配体诱导变化，这些变化改变了 NC 表面上苝二酰亚胺电子受体的取向。我们的工作表明，通过配体壳设计可以精细调节 NC 到分子的电荷转移，为研究人员提供了增强 NC 光催化的另一个手段。
