Magnetic modulation on chiroptical activities of nematically assembled carbon dots.

Effectively harnessing the assembly of achiral carbon dots into a chiral manner is a prominent step for applying carbon dots into the area of stereoselective optoelectronics and theranostics. Herein, magnetic-modulated and circularly polarized luminescence (CPL)-active photonic thin films were presented in this article via co-assembly and magnetic-mediation strategy of cellulose nanocrystals, carbon dots and magnetic nanoparticles. The photonic bandgap of the composite films is modulated via interfacial interactions between the building blocks, and more efficiently via external magnetic field which can further enhance the selective reflection of the films with a maximum CPL anisotropic factor as high as -0.92, indicating the optimized condition for achieving CPL signals is basically when the photonic bandgap (PBG) are close to the emission peaks of nanocomposite films, which may essentially facilitate the selective reflection effect and leads to the output of opposite CPL signals. Such strategy would inevitably boost the development of carbon dots based chiral devices and reagents into the realm of chirality-related biological issues and next generation chiral optoelectronics.