CO2-enhanced TADF of an ultra-stable Cu(i) cluster via guest–host π–π interaction†

Abstract

Efficient and reversible luminescence detection for CO₂ without solvent assistance is of great significance but remains challenging to achieve, due to the lack of efficient interaction between CO₂ molecules and the host emitting center. Benefiting from the abundant host–guest interactions, metal clusters provide a platform for detecting small molecules. However, the insufficient chemical stability of most metal clusters limits their practical applications. Here, we report a hydrophobic Cu(I) cluster (denoted as CuIDPO) with one-dimensional channels. Notably, it displays exceptional chemical stability in both acidic and alkaline aqueous solutions (pH = 1–14). More importantly, CuIDPO shows remarkable CO₂-induced luminescence enhancement (up to 385% under 1 bar CO₂), which can be applied to analyze CO₂ content (LOD = 7.7 mbar). Crystallographic analysis and theoretical calculations suggest the mechanism of CO₂-locking rotation of the phenyl groups in the Cu(I) cluster through guest–host π–π interaction, which is quite unique when compared to the known acid–base neutralization and framework flexibility adjustment mechanisms. Such luminescence CO₂ sensing shows advantages like ultrafast response and good reversibility. Additionally, CuIDPO-loaded membranes were fabricated for spatially resolved 2D visual detection.