Positive Encapsulation‐Induced Emission Control of Aggregation‐Induced Emission‐Active Anthracenes within Micellar Capsules in Water

ABSTRACT

Whereas aggregation‐induced emission (AIE) is a useful tool to develop photofunctional host systems, its guest usability has been largely unexplored within well‐defined host compounds so far, mainly owing to the absence of suitable cavities. Here we report the emission control of AIE‐active anthracenes upon efficient encapsulation by a terpene‐based micellar capsule in 100% water. Encapsulation of monopiperidyl‐substituted anthracenes yields a well‐defined host‐guest composite, with an average diameter of ∼3 nm, displaying green emission with high quantum yield ( Φ _F  = 53%). The yield is >50 and >10‐fold higher than those of the AIE‐dye in tetrahydrofuran (THF) and H ₂ O/THF suspension ( Φ _F  = 1 and 4%), respectively. This encapsulation‐induced emission (EIE) is altered by changing the substituent number/shape on the aromatic framework, leading to up to Φ _F  = 65%. Co‐encapsulation of the AIE‐anthracenes with aggregation‐caused quenching (ACQ) dyes (i.e., rubrene) enables strong yellow emission (up to Φ _F  = 55%) through high guest‐to‐guest Förster Resonance Energy Transfer (FRET) and antenna effect (up to 80% and 25, respectively) in the cavity. Furthermore, this strategy realizes strong pure‐white emission ( Φ _F  = 36%; CIE of (0.33, 0.33)) using other AIE‐active molecules in water. The photofunctions of AIE‐molecules can thus be largely expanded by the present capsule.