We report a series of butterfly-like phosphorescent pyrazolate bridged platinum binuclear complexes with controlled photoinduced structural change and dual emission. All these molecular butterflies can undergo molecular structure change in which the Pt–Pt distance shortens upon photoexcitation, which leads to the formation of two distinct excited states and dual emission in the steady state, that is, greenish-blue emission from the high-energy excited state at the long Pt–Pt distance and red emission from the low-energy excited state at the short Pt–Pt distance. The manipulation of photoinduced structural change and dual emission can be realized by controlling the bulkiness of the cyclometallating ligand and pyrazolate bridging ligand. By introducing bulky groups into the cyclometallating ligand, the photoinduced Pt-Pt distance shortening can be slowed down, resulting in dual emission with higher greenish-blue/red ratio, while introducing bulky groups into the pyrazolate bridges can speed up the photoinduced structural change, resulting in dual emission with higher red/greenish-blue ratio. Computational studies suggest that these molecular butterflies have various energy barriers for the photoinduced structural change and therefore different excited state dynamics. Overall, by careful control of the molecular structure, we have obtained colorful molecular butterflies flapping wings at various frequencies under light.

Synthetic control of photoinduced structural change and dual emission of phosphorescent molecular butterflies

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.