Carbon Dots and Their Sensing Behavior in Organic Medium

A carbon-based fluorescent nanomaterial, called carbon dot (CD), has emerged as a hot research area in the recent years due to its unique optical properties. This article tries to shed light on the photoluminescent (PL) behavior of CDs and their application as sensors. Different synthetic routes of CDs and some of the most probable causes of PL are mentioned along with various ways of surface modifications to tune these PL properties. Two types of sensing mechanisms—static and dynamic quenching—are discussed in detail with special emphasis on inner filter effect (IFE), fluorescence resonance energy transfer (FRET), photo-induced electron transfer (PET), etc. Application of CDs in sensing of various kinds of cations, anions and small molecules are shown. Finally, as an example, the proper way to design a sensor based on quenching of CDs’ blue PL emission in the vicinity of 2,4,6-trinitrophenol (TNP) molecules in an organic medium is elaborated. The sensor is reasonably stable and selective towards TNP in contrast to other nitrophenol analogues.