Electrochemiluminescence Platforms Based on Small Water‐Insoluble Organic Molecules for Ultrasensitive Aqueous‐Phase Detection

Abstract

Highly efficient detection in the aqueous phase for water-insoluble organic molecule probes is challenging.T he bright aggregated-state electrochemiluminescence (ECL) of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles by ac o-reactant approach was discovered, and ah eterogeneous aggregationinduced emission ECL (HAIE-ECL) was constructed at the electrode surface,s howing very high ECL efficiency (37.8 %) and selective recognition for industrially important DNBP plasticizer with al ow detection limit of 0.15 nm in the water phase.Am echanistic study indicates that ECL is mainly generated due to the high electron affinity of siloles and restriction of the intramolecular motions caused by their propeller-like noncoplanar structures.T his system realizes the sensing of organic-based ECL in the water phase by solving the crucial problems of water insolubility and aggregationcaused quenching (ACQ), and demonstrates potential for further application because of its design and high efficiency.Scheme 1. Chemical structures of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles and 1,1-dimethyl-3,4-diphenyl-2,5-bis(trimethylsilyl)silole.

Recent Advances in Aggregation‐Induced Electrochemiluminescence

“…Very recently,t he unique propeller-like structures of 1,1'-disubstituted 2,3,4,5-tetraphenylsiloles (Scheme 1b)h ave been facilely synthesized with simple, non-toxic, and highly stable archetypes of the AIE backbone. [49] The trend of strong AIE effect among these three structures was consistentw ith ECL intensityo rder:D MTPS < MPPS < HPS (Figure 12 a). By contrast, the ECL intensities of these silole monomers in homogeneous organic solvents decreased to approximatelyo ne twentieth (150 vs. 3000, Figure 12 b).…”

Benzosiloles with Crystallization‐Induced Emission Enhancement of Electrochemiluminescence: Synthesis, Electrochemistry, and Crystallography

“…DCM easily dissolves the films of 4T1 and 4T2 and clearly cannot be used. Although aqueous systems are widely reported, the films of 4T1 and 4T2 are highly hydrophobic and show no electrochemical or ECL behavior in purely aqueous system (Figure S3). After screening a number of common solvents for electrochemistry and ECL compatibility, we found that the films have relatively poor solubility in acetonitrile, although they are not yet insoluble enough in acetonitrile (see ECL results in Figure S4).…”

“…Highly π‐conjugated compounds containing silole rings (1‐silacyclopentadiene) have been adopted for use in polymeric solar cells, electrochemiluminescent sensors, and light‐emitting diodes . The unique photophysical properties of siloles arise from their low‐lying LUMO due to the σ*‐π* conjugation between the π* orbital of the butadiene moiety and the σ* orbital of the two exocyclic σ‐bonds on the silicon atom.…”

“…CIEE is undoubtedly desirable for light‐emitting electrochemical cells, organic light‐emitting diodes, etc., since the layer responsible for light emission in these devices is usually a crystalline film. In fact, some reports adopted heterogeneous ECL to improve analytical performance, but such a strategy is not readily feasible for existing organic ECL chromophores whose solid films are extreme hydrophobic and minimally wettable in aqueous systems but dissolve thoroughly in organic solvents.…”

“…To the best of our knowledge, this is the first example where the ECL performance is demonstrated to improve significantly by CIEE. Previously, aggregation‐induced emission enhancement (AIEE) of ECL, also known as AIECL, as recently summarized by Xu has been reported for 1,1′‐disubstituted 2,3,4,5‐tetraphenylsiloles, carboranyl carbazoles, tetraphenylethylene nanocrystals, and platinum complexes, but the performance difference between amorphous aggregate and crystalline film states has not been clearly shown prior to this report on benzosiloles. Is CIEE‐ECL just an example of a well‐ordered aggregate?…”