ABSTRACT The burgeoning reliance on fluorescence techniques to detect analytes of interest and visualize cellular processes has heightened the need for synthetic approaches to readily access new and underrepresented fluorophore classes, including those based on the 2,3‐naphthalimide scaffold. To address the lack of robust synthetic methodology, a general route to access structurally diverse fluorescent 2,3‐naphthalimides has been developed. Following the synthesis of the key 6‐bromo‐2,3‐naphthalic anhydride building block, imide formation and subsequent amination via Buchwald–Hartwig cross‐coupling methodology afforded a number of 6‐aminonaphthalimides with solvatochromic properties. Microscopy experiments in A549 cells highlight their potential as fluorescent probes for bio‐relevant imaging, with a 6‐piperazino‐2,3‐naphthalimide variant demonstrating pH‐responsive fluorescent behavior via photoinduced electron transfer.
ABSTRACT Aggregation‐responsive fluorescent probes are attractive for biological applications because molecular recognition can be transduced into optical signals through changes in molecular assembly. In this study, we report a series of carbohydrate‐conjugated Ar , O ‐BODIPYs that exhibit red/near‐infrared (NIR) fluorescence responsive to their aggregation state in aqueous media. The carbohydrate‐conjugated Ar , O ‐BODIPYs were readily synthesized by copper‐catalyzed azide–alkyne cycloaddition. Although the compounds exhibited intense fluorescence in DMSO, their fluorescence was strongly quenched in aqueous media. Dynamic light scattering, atomic force microscopy, and fluorescence lifetime measurements revealed that this quenching was associated with the formation of nanoscale aggregates. Importantly, the extent of aggregation and fluorescence quenching depended on the hydrophilic–hydrophobic balance between the Ar , O ‐BODIPY core and the appended carbohydrate moieties. Binding of a carbohydrate‐conjugated Ar , O ‐BODIPY to concanavalin A induced a pronounced fluorescence enhancement, indicating that protein binding promotes disruption of the quenched aggregates. Among the compounds examined, the glucose‐conjugated derivative showed the highest fluorescence intensity in living cells and efficiently stained several cell lines in the red/NIR region. These results demonstrate that controlling the hydrophilic–hydrophobic balance provides a useful molecular design strategy for tuning aggregation, fluorescence response, and cellular uptake, enabling carbohydrate‐conjugated Ar , O ‐BODIPYs to function as aggregation‐responsive fluorescent probes for protein recognition and bioimaging.
ABSTRACT Heteroatom‐doped macrocycles have emerged as a versatile platform for organic optoelectronics, particularly in organic light‐emitting diodes (OLEDs). By incorporating heteroatoms such as N, O, S, B, and Si into macrocyclic frameworks, researchers can precisely modulate electronic structures, band gaps, and photophysical properties. Compared to their linear counterparts, macrocyclic emitter's offer enhanced rigidity, which suppresses conformational disorder and vibrational relaxation, leading to higher photoluminescence quantum yields and more efficient thermally activated delayed fluorescence (TADF). The fixed topology also enables precise control of donor‐acceptor spatial arrangements, facilitating efficient reverse intersystem crossing and improved exciton utilization. This review summarizes recent advances in the synthesis of heteroatom‐doped macrocycles, focusing on three key strategies: palladium‐catalyzed C–N coupling, base‐catalyzed nucleophilic substitution, and Lewis acid‐catalyzed Friedel‐Crafts alkylation. Post‐synthetic functionalization further expands the structural and functional diversity of these macrocycles. We also highlight the application of these materials in high‐performance OLEDs and provide an outlook on the challenges and opportunities in this rapidly evolving field.
ABSTRACT The development of fluorescent probes to image the nucleus of live cells with high contrast and negligible photodamage is essential to overcome the limitations of existing nuclear stains and enable the visualization of chromatin dynamics with minimal perturbations on cellular functions. To this end, we synthesized a molecular construct integrating a borondipyrromethene (BODIPY) fluorophore and a Hoechst ligand within its covalent skeleton. In organic solvents, the Hoechst ligand has negligible influence on the photophysical properties of the BODIPY component. However, the characteristic fluorescence of the latter chromophore is completely suppressed in aqueous environments. Binding of the Hoechst ligand to double‐stranded DNA inhibits the quenching pathway to activate fluorescence. As a result, our fluorophore–ligand construct allows the imaging of nuclear DNA in live cells with no background fluorescence from the extranuclear space under excitation wavelengths in the green portion of the electromagnetic spectrum, ensuring minimal autofluorescence and photodamage.
ABSTRACT The upcycling of plastics into high‐value materials has emerged as a promising strategy to handle plastic waste. The production of block copolymers is an interesting route. This can be done by polymer / polymer interchange reaction, where telechelic polymers can play a pivotal role. The work describes the upcycling of aromatic polycarbonate (PC‐BPA) into PC‐BPA‐Polybutadiene (PBd) multiblock copolymers. The copolymers are synthesized via a transcarbonation reaction between hydroxytelechelic polybutadiene (PBd) and PC‐BPA using N‐heterocyclic bases as catalysts. A deep analysis of their microstructure is realized by NMR. The true formation of the copolymers is confirmed by DOSY experiments. It is shown that the nature of the catalyst strongly influences the microstructure of the resulting copolymers: TBD (1,5,7‐ triazabicyclo[4.4.0]dec‐5‐ene) provides high conversions and yields multiblock copolymers, while DMAP (4‐dimethylaminopyridine) affords higher molecular weights materials with lower conversions and predominantly diblock structures. The PBd content of the latter copolymers is much lower than that of the former. As consequence, the thermal properties also differ. This work provides, to the best of our knowledge, the first report of PC‐BPA/PBd multiblock copolymers.
