Multifunctional Fluorescent Material Based Red-emitting Carbon Dots for Cell Imaging and Photodynamic Sterilization.

In this paper, a new carbon dot (R1-CDs) was prepared by one-pot hydrothermal method by using 1,8-diaminonaphthalene and o-phthalic acid (o-PA) as precursors. Due to the high purity of R1-CDs, NMR analysis was performed to identify the types of H and C atoms in their graphene sheets. From our research findings, three important information was disclosed such as (1) five types H atoms are presented in R1-CDs; (2) 18 kinds of C atoms in the graphene sheets are observed, and 8 kinds of them are quaternary atoms, and 10 kinds of carbon atoms as tertiary one; (3) functional groups of -COOH and -NH2 from precursors cannot be inherited into the edges or defect sites of graphene sheet. Obviously, our research findings for the first time revealed the more details of chemical structures of CDs. We believe that our works can supply a general concept to fabricate CDs by selecting specific precursors, also can encourage CDs' development in a more "chemistry" way by employing NMR as a powerful method.