Fig. 5. Chiroptical properties of chiral carbon dots.

a–c CD spectra of carbon dots synthesized from L-/D-tryptophan and phenylene diamine in different solvents, with a blue, b yellow, and c red emission. d–f CD spectra of chiral carbon dots synthesized under different synthetic conditions: d reaction temperatures, e synthesis time, f precursor ratios between L-/D-cysteine and citric acid. g–i CD spectra of carbon dots synthesized from citric acid, urea, and L-cysteine by surface treatment (the sample called L-CD (ii)), and one-pot carbonization (sample L-CD (iii)): (g) Comparison of CD spectra of L-cysteine (L-cys, black line), L-CD (ii) (red line), and L-CD (iii) (pink line); h, i Absorption (black and red lines), its first derivative (black dashed lines) and circular dichroism spectra (pink lines) of L-CD (ii) (h) and L-CD (iii) (i). a–c Adapted with permission from⁵⁹ Copyright 2021 Wiley-VCH GmbH. d–f Adapted with permission from⁵⁷ Copyright 2020 Royal Society of Chemistry. g–i Adapted with permission from⁶² Copyright 2021 Royal Society of Chemistry