Open-shell organic luminescent radicals have received considerable attention recently, but it remains a formidable challenge to obtain circularly polarized luminescent (CPL) organic afterglow radicals, especially in nanomaterial systems. Here, we report the design and fabrication of intrinsically chiral carbon dots (CDs) with in situ generated radicals for CPL emission, followed by polyvinylpyrrolidone encapsulation to suppress non-radiative decays for long-lived afterglow. Upon UV irradiation, the CDs' electron-deficient naphthalimide (NI) moiety transforms gradually to the luminescent radicals, and the Förster resonance energy transfer from the pristine chiral CDs to the photoactivated radicals leads to the dynamically enhanced radical-based CPL afterglow with luminescent dissymmetry of 10-3 and an afterglow lifetime up to 265 ms. Moreover, owing to the photo-induced formation of NI-radical anions, photochromism from colorless to yellow and steady-state emission from blue to yellow were also observed, and these optical responses are reversible and highly sensitive to stimuli of light, temperature, humidity, and atmosphere. With the rich and dynamic photophysical features of the stimulus-responsive chromic and luminescent chiral nanomaterial, advanced anti-counterfeiting and multilevel information encryption on flexible substrates were realized, representing a remarkable step forward in integrating radical luminescence, CPL, photochromism, afterglow, and stimuli-response together for constructing multifunctional chiral nanomaterials.
Guo et al. (Tue,) studied this question.