Reversible and Stepwise Single‐Crystal‐to‐Single‐Crystal Transformation of a Platinum(II) Complex with Vapochromic Luminescence
Daisuke Saito, Tomasz Galica, Eiji Nishibori, Masaki Yoshida, Atsushi Kobayashi, Masako Kato
Abstract
Abstract The vapochromic single‐crystal‐to‐single‐crystal (SCSC) transformation of a highly luminescent Pt II complex bearing an N‐heterocyclic carbene [Pt(CN) 2 ( t Bu‐impy)] ( t Bu‐impyH + =1‐ tert ‐butyl‐3‐(2‐pyridyl)‐1 H ‐imidazolium) is reported. The trihydrate form of the complex, which exhibits blue 3 MMLCT emission owing to weak Pt⋅⋅⋅Pt interactions, changed its luminescence color from blue to yellowish‐green upon the desorption of water molecules while keeping the high emission quantum yield of more than 0.45. Variable‐temperature and continuous in‐situ tracking of single‐crystal X‐ray diffraction measurements revealed that the SCSC transformation proceeds reversibly by the release and reabsorption of water molecules, thereby changing the stacked structure slightly. As a result, the dynamics of vapor‐induced SCSC transformation were elucidated: that the anhydrous form returned to the original trihydrate form in a two‐step process under a water vapor atmosphere. In addition, the Pt II complex exhibited a similar SCSC response accompanied by a luminescence color change in the presence of methanol vapor, while being inactive toward ethanol vapor.