Ligand-Triggered Platinum(II) Metallacycle with Mechanochromic and Vapochromic Responses.

Supramolecular coordination complexes with solid-state stimuli-responsive characteristics are highly desirable but are rarely reported. Herein, we describe two coordination-driven self-assembled monoanthracene or dianthracene-based hexagonal metallacycles by subtle structure modification. Notably, the dianthracene-containing hexagon exhibits tricolor mechanochromic and vapochromic characteristics, while the monoanthracene-containing hexagon does not show obvious changes toward mechanical force. Further studies have indicated that changes in hexagon , especially the ulterior anthracene of hexagon in the molecular stacking through intermolecular interactions toward external stimuli, are responsible for the above behavioral differences. Furthermore, the present work also demonstrates a novel light-harvesting strategy for achieving high-contrast mechanochromic fluorescence involving solid-state energy transfer from hexagon to an organic carbazole derivant without mechanofluorochromism or tetraphenylethylene derivant exhibiting inconspicuous mechanofluorochromism.