Hybridized Host Functions in Polyaromatic Tube‐in‐Capsule Composites

Abstract Noncovalent hybridization of two types of host compounds has emerged as a promising strategy to develop unique functions, unattainable by either of the hosts. Here we report unusual spectroscopic features observed within a new hybrid host, formed by the combination of a polyaromatic tube and capsule, with rigid and flexible frameworks, respectively, in water. The resultant tube‐in‐capsule host selectively encapsulates rod‐like aromatic dyes (e.g., BODIPY and coumarin derivatives), yielding ternary host–guest composites bearing a dye‐in‐tube structure. The ternary composites exhibit strong emission (up to Φ F = ∼60%) from the bound dyes in water, with up to 45‐fold enhancement compared to the corresponding dye‐in‐capsule composites, due to the spatial isolation of the dyes in the tubular cavities. Detailed host–guest studies using dye derivatives and partial tube structures clearly indicate the importance of the rod‐like dye shape and tubular cavity for the present photofunctions. Furthermore, unusual remote chiroptical induction of encapsulated achiral dyes is readily demonstrated within a related hybrid host, where the achiral capsule is replaced with a chiral polyaromatic capsule. The dye‐based, pronounced circularly polarized emission (| g lum | = ∼3 × 10 −3 ) is observed only in this hybridized host–guest system.