State Key Laboratory of Advanced Optical Communication Systems and Networks, Key Laboratory for Laser Plasmas (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, 200240, China.
Institute of Molecular Medicine, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.
Nat Commun. 2021 Nov 25;12(1):6856. doi: 10.1038/s41467-021-27071-4.
Due to complex structure and surface functionalities, photoluminescence mechanisms of Carbon Dots are unknown, and it is challenging to synthesize Carbon Dots to achieve the desired optical properties. Herein, Carbon Dots simultaneously exhibiting high-color-purity (FWHM~24 nm) long wavelength one-photon fluorescence emission at 620 nm and NIR induced two-photon fluorescence emission at 630 and 680 nm are prepared by edge amino protonation treatment. Systematic analysis reveals that the protonation of 2,3-diaminophenazine changes the molecular state of Carbon Dots, decreases the photon transition band gap, and triggers red fluorescence emission with the dramatically narrowed peak width. As the oxidation products of reactant o-phenylendiamine, the emergence of 2,3-diaminophenazine as a photoluminescence determiner suggests that fluorophore products of precursor conversion are viable determinants of the desired luminescence properties of Carbon Dots. This work shows a new way for predicting and controlling photoluminescence properties of Carbon Dots, and may guide the development of tunable Carbon Dots for a broad range of applications.
由于结构复杂和表面功能，碳点的发光机制尚不清楚，且难以合成具有所需光学性质的碳点。在此，通过边缘氨基质子化处理，制备了同时表现出高光色纯度（半峰全宽~24nm）长波长单光子荧光发射（620nm）和近红外激发双光子荧光发射（630nm 和 680nm）的碳点。系统分析表明，2,3-二氨基吩嗪的质子化改变了碳点的分子状态，降低了光子跃迁能带隙，并引发了具有显著变窄峰宽的红色荧光发射。作为反应物邻苯二胺的氧化产物，2,3-二氨基吩嗪的出现表明前体转化的荧光团产物是碳点所需发光性质的可行决定因素。这项工作为预测和控制碳点的发光性质提供了一种新方法，并可能指导可调谐碳点的发展，以满足广泛的应用需求。
