Multi‐Macrocyclic Nanohoops Bearing Carbazole‐Embedded Cycloparaphenylenes as Geometry‐Adaptive Hosts Toward Fullerenes

Abstract

ABSTRACT Curved conjugated molecules with strained non‐planar geometries show unique properties valuable for supramolecular chemistry and optoelectronics, but their synthesis and modification remain challenging. We introduce carbazole‐embedded cycloparaphenylenes (CPPs) as versatile building blocks to overcome these limitations. Using Suzuki coupling and regioselective bromination, we created a functionalizable macrocyclic synthon. This enabled controlled multi‐component couplings to construct trimacrocyclic ( TMC ) and pentamacrocyclic ( PMC ) curved π‐systems. Structural analyses reveal TMC adopts a well‐defined C‐shape that self‐assembles into tubes, while PMC shows a deformed conformation. Their optical and electronic properties are size‐dependent, featuring strong fluorescence and stepwise oxidation to open‐shell polycations. Supramolecular studies show TMC acts as an adaptive host, forming distinct 1:1 complexes with C 60 (host–guest recognition‐induced host cavity expansion) and C 70 (encapsulation without conformational change). In comparison, PMC forms 2:1 (guest:host) complexes with C 60 or C 70 . Crystallographic and computational data indicate recognition is governed by the geometrically defined C‐shaped cavity rather than the macrocycle's electron‐rich nature.