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, P. R. China.
Department of Food Science and Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China.
Adv Sci (Weinh). 2023 Apr;10(11):e2207566. doi: 10.1002/advs.202207566. Epub 2023 Feb 5.
Due to the complicated nature of carbon dots (CDs), fluorescence mechanism of red fluorescent CDs is still unrevealed and features highly controversial. Reliable and effective strategies for manipulating the red fluorescence of CDs are urgently needed. Herein, CDs with one-photon excited (622 nm, QYs ≈ 17%) and two-photon (629 nm) excited red fluorescence are prepared by acidifying o-phenylenediamine-based reaction sediments. Systematic analysis reveals that the protonation of amino groups increases the particle surface potential, disperse the bulk sediments into nano-scale CDs. In the meanwhile, amino protonation of pyridinic nitrogen (-N=) structure inserts numerous n orbital energy levels between the π → π* transition, narrows the gap distance for photon transition, and induces red fluorescence emission on CDs. Present research reveals an effective pathway to activate CDs reaction sediments and trigger red emission, thus may open a new avenue for developing CDs with ideal optical properties and promising application prospects.
由于碳点（CDs）的复杂性，红色荧光 CDs 的荧光机制仍未被揭示，其特点极具争议性。因此，迫切需要可靠且有效的策略来操纵 CDs 的红色荧光。在此，通过酸化邻苯二胺基反应沉淀物制备了具有单光子激发（622nm，QYs≈17%）和双光子（629nm）激发红色荧光的 CDs。系统分析表明，氨基的质子化增加了颗粒表面电势，将大块沉淀物分散成纳米级 CDs。与此同时，吡啶氮（-N=）结构的氨基质子化在π→π*跃迁之间插入了许多 n 轨道能级，缩小了光子跃迁的间隙距离，从而诱导 CDs 发出红色荧光。本研究揭示了一种有效途径来激活 CDs 反应沉淀物并引发红色发射，从而为开发具有理想光学性能和广阔应用前景的 CDs 开辟了新途径。
