A Highly Strained All‐BODIPY‐Based Nanohoop

Highly strained π‐conjugated nanohoops present significant synthetic challenges but offer interesting platforms for exploring unique physical properties. Here, we report the synthesis of β‐β directly connected strained cyclic boron‐dipyrromethene (BODIPY) tetramer— [4]CBDP , with its structure unambiguously confirmed by single‐crystal X‐ray diffraction. Importantly, the radially conjugated architecture narrows the HOMO‐LUMO gap, yielding panchromatic absorption spanning the visible spectrum with an edge extending into the NIR‐I window, and resulting in a large Stokes shift (77 nm). Computational results indicate that [4]CBDP exhibits a high strain energy of 155 kcal/mol; yet it remains stable under ambient conditions (air/light) in both solution and the solid state.