Highly Efficient Aggregation-Induced Electrochemiluminescence of Al(III)-Cbatpy Metal-Organic Gels Obtained by Ultrarapid Self-Assembly for a Biosensing Application.

Abstract

Aggregation-induced electrochemiluminescence (AIECL) has attracted extensive interest due to the significant increase in ECL response by restricting free intramolecular rotation and torsion, but traditional AIECL emitters suffer from limited ECL efficiency, high cost, and complex synthetic steps, dramatically limiting their applications. Herein, novel Al(III)-Cbatpy metal-organic gels (Al(III)-Cbatpy-MOGs) with nanofiber morphology and ultrarapid coordination of Al3+ and 4'-carboxylic acid-2,2':6',2″-terpyridine (Cbatpy) are developed, which demonstrates an excellent AIECL enhancement behavior far beyond that reported in ECL supramolecular gels. In view of the strong affinity of N and O atoms in Cbatpy toward Al3+, Al(III)-Cbatpy-MOGs with high viscosity and stability can be assembled in one step within about 15 s, easily conquering the main predicaments of current AIECL emitters: complicated synthesis steps and poor film formation. Impressively, the ECL efficiency of Al(III)-Cbatpy-MOGs with superemission is about 20 times higher than that of individual Cbatpy molecules, which is attributed to the aggregation of the organic ligand Cbatpy restricting intramolecular rotation and torsion to reduce nonradiative relaxation. Furthermore, compared with traditional metal complexes, Al(III)-Cbatpy-MOGs show the benefits of remarkable biocompatibility and low cost without the involvement of any organic solvents, noble metals, and rare metals. As proof, a "signal-off" sensing platform based on an Al(III)-Cbatpy-MOGs/S2O82- system was constructed for the sensitive detection of dopamine (DA) with a low detection limit of 0.34 nM. This strategy provides a novel method to prepare cheap metal-organic gels as a highly efficient AIECL emitter, which is promising as a luminescent molecular device and biosensor for clinical diagnostic applications.