H2O rapidly constructs hydrogen bond networks to reinforce AIE of copper clusters: Fluorescence discoloration and enhanced behavior for alcohol content detection and latent fingerprints recognition

Aggregation-induced emission enhancement is one of the main methods for designing copper clusters (CuNCs) with high fluorescence intensity. In this study, H2O can rapidly construct stable hydrogen bonds with 2-thiobarbituric acid ligands of CuNCs, leading to denser aggregation between CuNCs. This process can occur at a level of intensity visible to the naked eye and can be completed within 30 s. As a result, the fluorescence turns to yellow with emission wavelength at 573 nm from red with emission wavelength at 638 nm, and the quantum yield has been increased to 50.03 %. The noticeable "turn on" phenomenon can be utilized for detecting alcohol content in low-alcohol liquor quality control. Additionally, bright luminous make Y-CuNCs can be employed for accurate identification of human latent fingerprints (LFPs), which can accurately identify the third level structure of the LFPs.