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

Abstract

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 <b>1</b> exhibits tricolor mechanochromic and vapochromic characteristics, while the monoanthracene-containing hexagon <b>4</b> does not show obvious changes toward mechanical force. Further studies have indicated that changes in hexagon <b>1</b>, especially the ulterior anthracene of hexagon <b>1</b> 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 <b>1</b> to an organic carbazole derivant <b>6</b> without mechanofluorochromism or tetraphenylethylene derivant <b>7</b> exhibiting inconspicuous mechanofluorochromism.