He Chen, Zhang Zhengyi, Wang Chen, Jiang Yishu, Weiss Emily A
Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.
J Phys Chem Lett. 2017 Oct 19;8(20):4981-4987. doi: 10.1021/acs.jpclett.7b02101. Epub 2017 Sep 28.
This Letter describes the reversible modulation of the electrostatic potential at the interface between a colloidal PbS quantum dot (QD) and solvent, through the protonation equilibrium of the QD's histamine-derivatized dihydrolipoic acid (DHLA) ligand shell. The electrostatic potential is sensitively monitored by the yield of photoinduced electron transfer from the QD to a charged electron acceptor, 9,10-anthraquinone-2-sulfonate (AQ). The permeability of the DHLA coating to the AQ progressively increases as the average degree of protonation of the ligand shell increases from 0 to 92%, as quantified by H NMR, upon successive additions of p-toluenesulfonic acid; this increase results in a decrease in the photoluminescence (PL) intensity of the QDs by a factor of 6.7. The increase in permeability is attributable to favorable electrostatic interactions between the ligands and AQ. This work suggests the potential of the combination of near-IR-emitting QDs and molecular quenchers as robust local H sensors.
本信函描述了通过胶体硫化铅量子点（QD）的组胺衍生化二氢硫辛酸（DHLA）配体壳层的质子化平衡，对量子点与溶剂界面处的静电势进行可逆调制。通过光致电子从量子点转移到带电电子受体9,10 - 蒽醌 - 2 - 磺酸盐（AQ）的产率，灵敏地监测静电势。随着通过1H NMR定量，在连续添加对甲苯磺酸后，配体壳层的平均质子化程度从0增加到92%，DHLA涂层对AQ的渗透性逐渐增加；这种增加导致量子点的光致发光（PL）强度降低了6.7倍。渗透性的增加归因于配体与AQ之间有利的静电相互作用。这项工作表明近红外发射量子点与分子猝灭剂组合作为强大的局部H传感器的潜力。
