TY - JOUR A1 - Meyerhofer, F. A1 - Dissinger, F. A1 - Weigert, Florian A1 - Jungclaus, J. A1 - Müller-Caspary, K. A1 - Waldvogel, S. R. A1 - Resch-Genger, Ute A1 - Voss, T. T1 - Citric Acid Based Carbon Dots with Amine Type Stabilizers: pHSpecific N2 - We report the synthesis and spectroscopic characteristics of two different sets of carbon dots (CDs) formed by hydrothermal reaction between citric acid and polyethylenimine (PEI) or 2,3-diaminopyridine (DAP). Although the formation of amide-based species and the presence of citrazinic acid type derivates assumed to be responsible for a blue emission is confirmed for both CDs by elemental analysis, infrared spectroscopy, and mass spectrometry, a higher abundance of sp2-hybridized nitrogen is observed for DAP-based CDs, which causes a red-shift of the n-π* absorption band relative to the one of PEI-based CDs. These CD Systems possess high photoluminescence quantum yields (QY) of ∼40% and ∼48% at neutral pH, demonstrating a possible tuning of the optical properties by the amine precursor. pH-Dependent spectroscopic studies revealed a drop in QY to < 9% (pH ∼ 1) and < 21% (pH ∼ 12) for both types of CDs under acidic and basic conditions. In contrast, significant differences in the pHdependency of the n-π* transitions are found for both CD types which are ascribed to different (de)protonation sequences of the CD-specific fluorophores and functional groups using Zeta potential analysis. KW - Fluorescence KW - Particle KW - Nano KW - Surface group analysis KW - Carbon dot KW - C-dot KW - Fluorescent probe KW - Quantum yield KW - Synthesis KW - IR KW - MS KW - Polymer KW - Ligand PY - 2020 U6 - https://doi.org/10.1021/acs.jpcc.9b11732 VL - 124 IS - 16 SP - 8894 EP - 8904 PB - American Chemical Society AN - OPUS4-50813 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -