Bicomponent Fluorescent System Composed of Peptide-Substituted Naphthalenediimide and Carbon Dots as Nanothermometer

This study vividly demonstrates the formation of a fluorescence-based temperature-sensing thermometer, obtained from a nanohybrid material, composed of self-assembled peptide-appended core-substituted naphthalenediimide and carbon nanodots. The nanohybrid system can exhibit variable fluorescence output depending on the changes in the temperature within a wide range of −25 to 90 °C. This two-component optically active hybrid material has been designed and constructed from cyan-emitting carbon dots (C-dots) and a red-emitting π-conjugated peptide-appended naphthalenediimide-based molecule (c-NDI-P) in ortho-xylene at room temperature (25 °C). At very low temperatures (−25 °C), the system emits a blue color, while at high temperatures (90 °C), the emission is reddish pink. If the temperature is around −3 °C, the system exhibits cyan emission, and at room temperature (25 °C), a white-colored emission is obtained. Förster resonance energy transfer (FRET) from the donor C-dots to the acceptor c-NDI-P is responsible for the white light emission. This is a unique example of a two-component fluorescent nanoscale thermometry system that exhibits a blue to cyan to reddish pink emissive color passing through a white light at room temperature (25 °C).