Depolymerization-Induced Electrochemiluminescence of Insoluble Porphyrin in Aqueous Phase.

Exploring efficient and robust electrochemiluminescence (ECL) performance of liposoluble porphyrins in aqueous phase for analytical purposes especially for important biological targets is still very challenging. In this work, a novel depolymerization-induced electrochemiluminescence (DIECL) of porphyrin and ß-cyclodextrin (ß-CD) self-assembly through a coreactant route was discovered. Among the studied meso-tetrasubstituted porphyrins, self-assembly of 5,10,15,20-tetrakis(4-hydroxyphenyl) porphyrin (THPP) and ß-CD (THPP@ß-CD) exhibits the best DIECL behavior with high efficiency (21.8%) as well as good reproducibility and stability. A mechanistic study suggests that the facile complexation of porphyrins with amphiphilic ß-CD via hydrogen bonding interaction greatly improves the water insolubility and the aggregation-caused deficient ECL of liposoluble porphyrins in aqueous solution. Furthermore, because of the strong hydrogen bonding between the hydroxyl groups on THPP@ß-CD and a highly electronegative substrate, such THPP@ß-CD is found to serve as an efficient luminophore for recognition of most electronegative fluoride (F-) in the aqueous phase with high sensitivity and selectivity, together with a low limit of detection (0.74 µΜ). The simplicity of this THPP@ß-CD and its unique DIECL property in current work provides a new guide for the ECL applications of liposoluble porphyrins in aqueous phase.

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

Highly efficient detection in the aqueous phase for water-insoluble organic molecule probes is challenging. The bright aggregated-state electrochemiluminescence (ECL) of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles by a co-reactant approach was discovered, and a heterogeneous aggregation-induced emission ECL (HAIE-ECL) was constructed at the electrode surface, showing very high ECL efficiency (37.8 %) and selective recognition for industrially important DNBP plasticizer with a low detection limit of 0.15 nm in the water phase. A mechanistic 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. This system realizes the sensing of organic-based ECL in the water phase by solving the crucial problems of water insolubility and aggregation-caused quenching (ACQ), and demonstrates potential for further application because of its design and high efficiency.