Related Experiment Video
Updated: Jul 1, 2026
Iridium(III) Luminescent Probe for Detection of the Malarial Protein Biomarker Histidine Rich Protein-II
Published on: July 7, 2015
Rapid and Selective Fluorescent Sensing of Histidine Driven by Metal-Specific Displacement in AIE-Based Complexes
Zhizhong Zhao1, Lijuan Liang1, Xin Wang1
1State Key Laboratory of Natural Product Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
None:
The rational control of ligand substitution in metal complexes remains underexplored for turn-on fluorescent probes. Here, varying the metal center (Co2+, Ni2+, or Cu2+) in AIE-based complexes M(L)2 (L = tetraphenylethylene-based β-diketone) enables precise tuning of metal-ligand bond dissociation, dictating competitive ligand exchange with histidine (His). Single-crystal X-ray diffraction confirmed the structures. All complexes are nonemissive in the aggregated state due to paramagnetic quenching. Upon His addition, only Ni(L)2 undergoes rapid and complete ligand displacement, generating a strong fluorescence turn-on signal within 10 min at room temperature. Co(L)2 reacts much more slowly (>560 min), while Cu(L)2 shows no change. DFT calculations based on crystal structures quantify Gibbs free energy changes: spontaneous displacement in Ni(L)2 correlates with favorable ligand dissociation energetics, whereas Cu(L)2 is thermodynamically trapped. Exploiting this metal-dependent reactivity, Ni(L)2 serves as a highly selective and rapid fluorescent probe for His, discriminating against 20 other amino acids with a detection limit of 4.66 nM. This work establishes a coordination chemistry strategy for designing small-molecule probes by modulating metal-dependent dissociation energetics in AIE complexes, moving beyond conventional PET mechanisms.
