Amination and Protonation Facilitated Novel Isoxazole Derivative for Highly Efficient Electron and Hole Separation.

It is of great importance to understand the intrinsic relationship between phototautomerization and photoelectric properties for the exploration of novel organic materials. Here, in order to chemically control the protonation process, the aminated isoxazole derivative (2,2'-(isoxazolo[5,4-d]isoxazole-3,6-diyl)dibenzenaminium, DP-DA-DPIxz) with -N═ as the proton acceptor was designed to achieve the twisted intramolecular charge transfer (TICT) state which was triggered by an excited-state intramolecular proton transfer (ESIPT) process. This kind of protonation enhanced the intramolecular hydrogen bonding, conjugative effect, and steric hindrance effects, ensuring a barrierless spontaneous TICT process. Through the intramolecular proton transfer, the configuration torsion and conjugation dissociation of the DP-DA-DPIxz molecule was favored, which led to efficient charge separation and remarkable variations in light-emitting properties. We hope the present investigation will provide a new approach to design novel optoelectronic organic materials and shine light on the understanding of the charge transfer and separation process in molecular science.

Electrophilicity Modulation for Sub-ppm Visualization and Discrimination of EDA.

Precise and timely recognition of hazardous chemical substances is of great significance for safeguarding human health, ecological environment, public security, etc., especially crucial for adopting appropriate disposition measures. Up to now, there remains a practical challenge to sensitively detect and differentiate organic amines with similar chemical structures with intuitive analysis outcomes. Here, a unique optical probe with two electrophilic recognition sites for rapid and ultra-sensitive ratiometric fluorescence detection of ethylenediamine (EDA) is presented, while producing distinct fluorescence signals to its structural analog. The probe exhibits ppb/nmol level sensitivity to liquidous and gaseous EDA, specific recognition toward EDA without disturbance to up to 28 potential interferents, as well as rapid fluorescence response within 0.2 s. By further combining the portable sensing chip with the convolutional algorithm endowed with image processing, this work cracked the problem of precisely discriminating the target and non-targets at extremely low concentrations.