Supramolecule-Originated Emission: A Room-Temperature Phosphorescence 2D Ionic H-Bond Network from Nonemissive Aliphatic Derivatives

Abstract

Supramolecular materials exhibiting unique functions unavailable from their individual components are attracting great attention. Here, we report a novel supramolecule emission strategy, where the emission originated from a two-dimensional (2D) ionic hydrogen bond (H-bond) supramolecular network. High-quality crystals were obtained by rapid self-assembly of liquid aliphatic amine and ketone. The 2D ionic H-bonding network was characterized by single-crystal X-ray diffraction (XRD) that shows a planar electron system similar to aromatic species. First-principles calculations demonstrated that the charge-separated transition process and high spin-orbital coupling constants of the rigid supramolecular structure contribute to the enhanced singlet-triplet intersystem crossing process. The emission could be well regulated via the substituents of either the enol or amine part, and a maximum quantum efficiency of 26% was realized. The emission system demonstrated stable room-temperature phosphorescence (RTP), which is even hard to obtain for aromatic species, and the lifetime reached 0.45 s with an 8% luminescence quantum yield. For application, with liquid amine and enol as ink, high-quality RTP patterns can be fabricated by computer-controlled precision printing. Our findings will surely bring completely fresh thinking for photoluminescence and other functions purely originated by the supramolecular structure.