Sensing analysis is significantly important for human health and environmental safety. In this review, POPs used as platforms for various sensing applications have been summarized and discussed.

Polycyclic aromatic hydrocarbons (PAHs) with boron–nitrogen (BN) moieties have attracted tremendous interest due to their intriguing electronic and optoelectronic properties. However, most of the BN-fused π-systems reported to date are difficult to modify and exhibit traditional aggregation-caused quenching (ACQ) characteristics. This phenomenon greatly limits their scope of application. Thus, continuing efforts to seek novel, structurally distinct and functionally diverse structures are highly desirable. Herein, we proposed a one-stone-two-birds strategy including simultaneous exploration of reactivity and tuning of the optical and electronic properties for BN-containing π-skeletons through flexible regioselective functionalization engineering. In this way, three novel functionalized BN luminogens (DPA-BN-BFT, MeO-DPA-BN-BFT and DMA-DPA-BN-BFT) with similar structures were obtained. Intriguingly, DPA-BN-BFT, MeO-DPA-BN-BFT and DMA-DPA-BN-BFT exhibit completely different emission behaviors. Fluorogens DPA-BN-BFT and MeO-DPA-BN-BFT exhibit a typical ACQ effect; in sharp contrast, DMA-DPA-BN-BFT possesses a prominent aggregation induced emission (AIE) effect. To the best of our knowledge, this is the first report to integrate ACQ and AIE properties into one BN aromatic backbone with subtle modified structures. Comprehensive analysis of the crystal structure and theoretical calculations reveal that relatively large twisting angles, multiple intermolecular interactions and tight crystal packing modes endow DMA-DPA-BN-BFT with strong AIE behavior. More importantly, cell imaging demonstrated that luminescent materials DPA-BN-BFT and DMA-DPA-BN-BFT can highly selectively and sensitively detect lipid droplets (LDs) in living MCF-7 cells. Overall, this work provides a new viewpoint of the rational design and synthesis of advanced BN–polycyclic aromatics with AIE features and triggers the discovery of new functions and properties of azaborine chemistry.

This review discusses the synthesis, functionalization and applications of BN-embedded aromatic hydrocarbons, emphasizing their role in organic optoelectronics, biomedicine and imaging while providing insights for future research.

Peptide bonds, the amide bonds formed between α-amino acids, constitute the backbone of peptides and proteins. Although peptide bonds can be constructed efficiently under mild reaction conditions in nature, their chemical approach imposes great challenges on chemists. The notorious racemization/epimerization issue caused by the “overactivation” of the carboxylic groups by using conventional coupling reagents always complicated peptide synthesis and purification. Alternatively, active esters with well-defined structures and moderate reactivity, formed in situ or prior prepared, play a crucial role in suppressing racemization/epimerization. Herein, we systematically and critically summarized the pros and cons of using active esters in peptide syntheses with a hope of stimulating novel innovations for disruptive peptide synthesis strategies.