Distortional Supramolecular Isomers of Polyrotaxane Coordination Polymers: Photoreactivity and Sensing of Nitro Compounds

Distortional isomers, or bond‐stretch isomers, differ only in the length of one or more bonds, which is due to crystallographic disorder in most cases. The term distortional isomerism is introduced to describe the structures of polyrotaxane 2D coordination polymers (CPs) that differ only by the relative positions in the neighboring entangled axles. A large ring and a long spacer ligand in 2D CPs yielded four different supramolecular isomers, of which two have an entangled polyrotaxane structure. One pair of CC bonds in the spacer ligand is well‐aligned in one isomer and undergoes [2+2] cycloaddition reaction, whereas the other isomer is photoinert. They also have different sensing efficiency for several aromatic nitro compounds. However, both isomers show selective PL quenching for the Brady’s reagent. Structurally similar supramolecular isomers with different photochemical reactivity and sensing abilities appear to be unprecedented. Isomere Polyrotaxane: Vier supramolekulare Isomere von Koordinationspolymeren wurden synthetisiert, darunter zwei mit Polyrotaxanstrukturen, die sich nur in der Position des Rings auf der benachbarten Achse unterscheiden. Diese beiden Isomere zeigen unterschiedliches Verhalten unter UV‐Bestrahlung und bei der Erkennung organischer Nitroverbindungen.