Selective coordination and localized polarization in graphene quantum dots: Detection of fluoride anions using ultra-low-field NMR relaxometry  

作　　者：Yongqiang Li Yi Xiao Quan Tao Mengmeng Yu Li Zheng Siwei Yang Guqiao Ding Hui Dong Xiaoming Xie 

机构地区：[1]State Key Laboratory of Functional Materials of Informatics,Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences(CAS),Shanghai 200050,China [2]CAS Center for Excellence in Superconducting Electronics(CENSE),Chinese Academy of Sciences,Shanghai 200050,China [3]Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Chinese Chemical Letters》2021年第12期3921-3926,共6页中国化学快报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (Nos. 11874378, 11804353, and 11774368);the Science and Technology Commission of Shanghai Municipality (Nos. 19511107100, 19511107400)。

摘　　要：The development of ultra-sensitive methods for detecting anions is limited by their low charge to radius ratios, microenvironment sensitivity, and p H sensitivity. In this paper, a magnetic sensor is devised that exploits the controllable and selective coordination that occurs between a magnetic graphene quantum dot(GQD) and fluoride anion(F–). The sensor is used to measure the change in relaxation time of aqueous solutions of magnetic GQDs in the presence of F–using ultra-low-field(118 μT) nuclear magnetic resonance relaxometry. The method was optimized to produce a limit of detection of 10 nmol/L and then applied to quantitatively detect F–in domestic water samples. More importantly, the key factors responsible for the change in relaxation time of the magnetic GQDs in the presence of F–are revealed to be the selective coordination that occurs between the GQDs and F–as well as the localized polarization of the water protons. This striking finding is not only significant for the development of other magnetic probes for sensing anions but also has important ramifications for the design of contrast agents with enhanced relaxivity for use in magnetic resonance imaging.

关 键 词：Graphene quantum dots COORDINATION POLARIZATION RELAXOMETRY Magnetic sensor Nuclear magnetic resonance Fluoride anion 

分 类 号：O641.4[理学—物理化学] O657.2[理学—化学]