One-Step Solvothermal Synthesis of Red Chiral Carbon Dots for Multioptical Detection of Water in Organic Solvents

Water is a typical impurity in organic solvents, so it is significant to determine its presence quantitatively and qualitatively. Herein, we developed UV–visible, fluorescence, and circular dichroism methods for water detection based on red-emitting chiral carbon dots (RC-CDs). Chiral CDs are generating much interest because of their remarkable optical characteristics, but synthesizing RC-CDs and maintaining their chiral structures remain challenging in terms of precursors and synthesis methods. In this work, we reported a new approach for synthesizing RC-CDs via simple solvothermal processing of the common precursors l-tyrosine (l-Tyr) and o-phenylenediamine (o-PDA) utilizing H2O/H2SO4 as the solvent. The as-prepared RC-CDs exhibit an ultranarrow full width at half-maximum (fwhm = ∼27 nm) emission at 627 nm with a quantum yield of 16.2%. Moreover, the prepared RC-CDs were applied to evaluate their multioptical response to detect water from 10 to 100% (v/v) in ethanol. RC-CDs demonstrate remarkable linearity in UV–visible, fluorescence, and circular dichroism spectroscopy to the water content changes in ethanol. Notably, the use of chiral CDs in optical detection through circular dichroism has not been reported before. In summary, we believe that this work can expand the synthetic routes of RC-CDs and provide an early step for exciting opportunities for the design of functional chiroptical materials.