Enhancement of Phosphorescence and Unimolecular Behavior in the Solid State by Perfect Insulation of Platinum–Acetylide Polymers

Controlling the thermal fluctuations and molecular environment of a phosphorescent polymer backbone is vital to enhancing its phosphorescence intensity in the solid state. Here, we demonstrate enhanced phosphorescence control through a systematic investigation of cyclodextrin-based insulated platinum–acetylide polymers with well-defined coverage areas. Modification of the coverage areas revealed two un­preced­ented effects of macrocyclic insulation on phos­phor­escence behavior. First, the insulation of particular areas suppresses the thermal relaxation processes of the triplet species because of the restriction of structural fluctuations. Cyclic insulation fixes a polymer chain and concomitantly enhances the phosphorescence intensity in both the solution and solid states. Second, complete three-dimensional insulation protects the polymer from interactions with other platinum and acetylide units, and even oxygen molecules. Notably, these polymers display identical phosphorescence behaviors in both the solution and solid states, essentially achieving “unimolecular phos­phorescence.”