Solvent-dependent red emissive carbon dots and their applications in sensing and solid-state luminescence

Herein, a kind of red emissive carbon dots (BNCDs) based on 1,1'-binaphthyl-2,2'-diamine (BNDM) and citric acid as carbon source were prepared through one-pot solvothermal method. The synthesized BNCDs have uniform size distribution, photobleaching resistance, and excitation wavelength-independent emission performance with the optimal fluorescence at lambda(ex)/lambda(em) = 540/603 nm. The composite films of BNCDs in polyvinyl alcohol (PVA) matrix exhibited bright red emission under ultraviolet irradiation, indicating their potential in solid-state luminescence. Also, BNCDs shows unique solvent-dependent phenomenon, the optical behavior can be tuned by the change of solvent polarity. Another striking observation was that BNCDs can be applied as a fluorescence sensor for highly sensitive quantitative detection of trace water in organic solvents because it's polarity-sensitive property. Through fluorescence "on-off-on " mechanism, BNCDs could be used as a fluorescence sensor for detection of Fe3+ and F- with LOD of 0.219 and 0.0104 mu mol L-1, respectively. This strategy offers an efficient approach for preparing red emissive carbon dots and lays a foundation for its multi-functional application.