A Phosphorescent Molecular “Butterfly” that undergoes a Photoinduced Structural Change allowing Temperature Sensing and White Emission

Abstract

A butterfly-like phosphorescent platinum(II) binuclear complex can undergo a 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. This photoinduced molecular structure change has a strong dependence on the molecule’s surrounding environment, allowing its application as self-referenced luminescent sensor for solid–liquid phase change, viscosity, and temperature, with greenish-blue emission in solid matrix and rising red emission in molten liquid phase. With proper control of the surrounding media to manipulate the structural change and photophysical properties, a broad white emission can be achieved from this molecular butterfly.