Molecular engineering of thiophene- and pyrrole-fused core arylamine systems: Tuning redox properties, NIR spectral responsiveness and bacterial imaging applications.

The thiophene- and pyrrole-fused heterocyclic compounds have garnered significant interest for their distinctive electron-rich characteristics and notable optoelectronic properties. However, the construction of high-performance systems within this class is of great challenge. Herein, we develop a series of novel dithieno[3,2-b:2',3'-d] pyrrole (DTP) and tetrathieno[3,2-b:2',3'-d] pyrrole (TTP) bridged arylamine compounds (DTP-C4, DTP-C12, DTP-C4-Fc, TTP-C4-OMe, TTP-C4, and TTP-C12) with varying carbon chain lengths. The pertinent experimental results reveal that this series of compounds undergo completely reversible multistep redox processes. Notably, TTP-bridged compounds TTP-C4 and TTP-C12 exhibit impressive multistep near-infrared (NIR) absorption alterations with notable color changes and electroluminescent behaviors, which are mainly attributed to the charge transfer transitions from terminal arylamine units to central bridges, as supported by theoretical calculations. Additionally, compound DTP-C4 demonstrates the ability to visually identify gram-positive and gram-negative bacteria. Therefore, this work suggests the promising electroresponsive nature of compounds TTP-C4 and TTP-C12, positioning them as excellent materials for various applications. It also provides a facile approach to constructing high-performance multifunctional luminescent materials, particularly those with strong and long-wavelength NIR absorption capabilities.

Novel Dual-Emission Emitters Featuring Phenothiazine-S-Oxide and Phenothiazine-S,S-Dioxide Motifs.

In this study, we have successfully designed and synthesized two novel dual-emission emitters featuring phenothiazine-5-oxide and phenothiazine-5,5-dioxide motifs, characterized by highly lopsided and asymmetric conformational states. Through rigorous spectral examinations and DFT calculations, the compounds exhibit distinctive ICT phenomena, coupled with efficient emission in solid states and AIEE characteristics under high water fractions in DMF/H2O mixtures. These non-planar luminogens exhibit vibrant green and blue solid-state luminescence, with fluorescence quantum yields of 24.1 % and 15.21 %, respectively. Additionally, they both emit green fluorescence in THF solution, with notable emission quantum yields (QYs) 36.4 % and 30.4 %. Comprehensive theoretical investigations unveil well-defined electron cloud density separation between the energies of HOMO/LUMO levels within the two luminogens. Notably, the targeted molecule harboring the phenothiazine-S,S-dioxide motif also demonstrates remarkable reversible mechanofluorochromic properties. Moreover, we testify their potential in applications such as solid-state rewritable information storage and live-cell imaging in solution states. Through theoretical calculations and comparative studies, we have explored the intrinsic relationship between molecular structure and performance, effectively screening and identifying new fluorescent molecules exhibiting outstanding luminescent attributes. These discoveries establish a robust theoretical and technical foundation for the synthesis and application of efficient DSE-based MFC materials, opening new avenues in the realm of advanced luminescent materials.

A Protocol for Activated Bioorthogonal Fluorescence Labeling and Imaging of 4-Hydroxyphenylpyruvate Dioxygenase in Plants.

4-Hydroxyphenylpyruvate dioxygenase (HPPD) plays a crucial role in the synthesis of nutrients needed to maintain optimal plant growth. Its level is closely linked to the extent of abiotic stress experienced by plants. Moreover, it is also the target of commercial herbicides. Therefore, labeling of HPPD in plants not only enables visualization of its tissue distribution and cellular uptake, it also facilitates assessment of abiotic stress of plants and provides information needed for the development of effective environmentally friendly herbicides. In this study, we created a method for fluorescence labeling of HPPD that avoids interference with the normal growth of plants. In this strategy, a perylene-linked dibenzyl-cyclooctyne undergoes strain-promoted azide-alkyne cycloaddition with an azide-containing HPPD ligand. The activation-based labeling process results in a significant emission enhancement caused by the change in the fluorescent forms from an excimer to a monomer. Notably, this activated bioorthogonal strategy is applicable to visualizing HPPD in Arabidopsis thaliana, and assessing its response to multiple abiotic stresses. Also, it can be employed to monitor in vivo levels and locations of HPPD in crops. Consequently, the labeling strategy will be a significant tool in investigations of HPPD-related abiotic stress mechanisms, discovering novel herbicides, and uncovering unknown biological functions.

Pentacyclic and Hexacyclic Osmaarynes and Their Derivatives.

Although osmabenzyne, osmanaphthalyne, osmaphenanthryne, and osmaanthracyne have been previously reported, the synthesis of polycyclic osmaarynes is still a challenge. Herein, we report the successful synthesis of the first pentacyclic osmaarynes (pyreno[b]osmabenzynes 1 a and 2 a) and hexacyclic osmaaryne (peryleno[b]osmabenzyne 3 a). Nucleophilic reaction of osmaarynes was used to obtain the corresponding pyreno[b]osmium complexes (1 and 2) and peryleno[b] osmium complex (3), which exhibited near-infrared luminescence and aggregation-induced emission (AIE) properties. Complexes 2 and 3 are resistant to photodegradation, and complex 2 has better photothermal conversion properties than 3.