Aggregation-Induced Electrochemiluminescence of Tetraphenylbenzosilole Derivatives in an Aqueous Phase System for Ultrasensitive Detection of Hexavalent Chromium

Abstract

Herein, aggregation-induced electrochemiluminescence (AIECL) of tetraphenylbenzosilole derivatives in an aqueous phase system with the participation of a co-reactant was systematically investigated for the first time. All organics that we studied exhibit excellent stability and dramatically enhanced electrochemiluminescence (ECL) and photoluminescence (PL) emission when the water fraction increases. The influence of substituents in the structure of tetraphenylbenzosilole derivatives on AIECL performance was proved by fluorescence, cyclic voltammetry, and related theoretical calculation. Among them, 2,3-bis­(4-cyanophenyl)-1,1-diphenyl-benzosilole (TPBS-C) with strong electron-withdrawing cyano groups exhibits the best ECL behavior with the highest ECL efficiency (184.36%). The strongest ECL emission of TPBS-C not only stems from the aggregated molecules that restrict the intramolecular motion of peripheral phenyl groups, which inhibits the nonradiative transition, but also comes from the fact that TPBS-C has the lowest reduction potential, and twice the reduction process of TPBS-C occurs to produce more anion radicals (TPBS-C· –). Significantly, the ECL sensor based on TPBS-C nanoaggregates exhibits excellent detection performance for toxic Cr­(VI) with a wide linear range from 10–12 to 10–4 M and an extremely low detection limit of 0.83 pM. This work developed an efficient luminophore with unique AIECL properties and realized the ultrasensitive detection of Cr­(VI) in the aqueous phase system.

Hydrogen Bond Organic Frameworks as a Novel Electrochemiluminescence Luminophore: Simple Synthesis and Ultrasensitive Biosensing

“…14 Notably, heterocyclic compounds 15 and supramolecules 16 have been exploited as ECL emitters in aqueous systems, greatly abolishing the detrimental quenching stacking. Unfortunately, the high cost and tedious synthesis of AIECL molecules and organic ligands 17 still hamper the advancement of ECL applications in bioassays. In the AIE mechanism, such organic molecules show weak fluorescence (FL) in an aqueous states but emit strong FL signals in the aggregated cases.…”

Aggregation-Induced Emission in Electrochemiluminescence: Advances and Perspectives

“…This concept was proved in the sensing of the industrial plasticizer di-n-butyl ortho-phthalate (DNBP). More recently, this group has also studied the effects of a 4-substitution on the phenyl groups of tetraphenylbenzosiloles (TPBS), observing the positive effect of electron withdrawing groups on the enhancement of the AIECL response [60]. The competing reduction of Cr 2 O 7 2− was exploited in order to use the system for the detection of hexavalent chromium [60].…”

Arousing Electrochemiluminescence Out of Non-Electroluminescent Monomers within Covalent Organic Frameworks

“…The discovery of aggregation-induced luminescence (AIE) has carved out an innovative avenue for achieving ECL of organic phosphors in aqueous solutions leading to aggregation-induced ECL (AIECL) materials, such as siloles derivatives, , tetraphenylethene derivatives, coumarin derivatives, and carboranyl carbazoles . Albeit the AIE luminescence was achieved in poor solvents or on electrode surfaces by restricting intramolecular movement, the aggregation products are random and disordered, making it difficult to figure out the relationship between the molecular structure and AIE performance.…”

“…Furthermore, modern ECL luminophores are almost entirely based on co-reactants represented by tri- n -propylamine and S 2 O 8 2– to provide stable free radical ions, − but these corrosive and biotoxic co-reactants have limited “green” and environment friendly applications. Besides, due to a lack of a general design strategy for ECL luminophores, finding new and efficient ECL emitters is extremely difficult and researchers have been mostly restricted to modifying existing structures to improve luminous performance. ,, …”