Near-Infrared Photooxygenation Theranostics Used for the Specific Mapping and Modulating of Amyloid‑β Aggregation

The photooxygenation of amyloid-β (Aβ) protein is considered a promising strategy against Alzheimer’s disease (AD). The inhibition of Aβ aggregation or depolymerization of Aβ aggregates can effectively alleviate and improve the condition of AD. Herein, we report a series of “off–on” near-infrared quinolinium photosensitizers (QM20–QM22) based on D-π-A structures using a target-sensing catalyst activation (TaSCAc) strategy. They exhibit turn-on fluorescence when bonded to Aβ aggregates and generate singlet oxygen to achieve the specific imaging and photooxygenation of Aβ aggregates, leading to attenuated Aβ aggregates, enhancing their clearance through the microglial lysosomal pathway, decreasing their neurotoxicity. This study will shed light on the development of the photooxygenation of misfolded proteins for the treatment of neurodegenerative diseases

“Crossbreeding” Small-Molecular Weight NIR-II Flavchromenes Endows Activatable Multiplexed In Vivo Imaging

High-performance near-infrared-II (NIR-II) fluorophores have attracted tremendous attention for in vivo dynamic bioimaging. However, the lack of stable, bright, and biocompatible molecular fluorophores becomes a major barrier on the way to the widespread endorsement of NIR-II bioimaging for clinic diagnosis. Here we propose a π-conjugated “crossbreeding” dyad strategy to develop novel desirable NIR-II dyes, flavchromenes (flav+chromene) integrated from two individual fluorophores of flavylium and chromene via a short methine bridge, affording valuable features of extending spectra into the NIR-II region and conferring a substantive leap in the photophysical properties. Notably, these crossbreeding NIR-II dyes have small molecular weights, high molar extinction coefficients, and outstanding chemical stability. As demonstrated, the elaborated probe Flavchrom-4 endows activatable dual-modal in vivo imaging of endogenous β-galactosidase activity, along with lighting-up NIR-II fluorescence signals and dramatically enhanced photoacoustic signals (16.3-fold). This concise π-conjugated crossbreeding dyad strategy brings forth high-performance NIR-II fluorophore scaffolds with small molecular weights, high stability, and good brightness, thus greatly expanding high-resolution activatable in vivo imaging tools for intact tissues and living animals

Theoretical study about the thermal stability and detonation performance of the nitro-substituted derivatives of 4-(1H-1,2,4-triazol-1-yl) pyrimidine

The nitro groups are introduced into 4-(1H-1,2,4-triazol-1-yl) pyrimidine to substitute the hydrogen atoms successively, through which a total of 31 derivatives are constructed to look for high energy density compounds (HEDCs). To probe the thermal stabilities, the heats of formation (HOFs) are calculated by using the G3MP2 method. To explore the dynamic stability, the natural bond orbital (NBO) analysis is performed to confirm the trigger bond, for which the bond dissociation energy is calculated using the B3PW91 method with the 6-311 + G(d,p) basis set. Furthermore, the detonation velocity (D), the detonation pressure (P), the molecular density (ρ), the explosive heat (Q), and character height (H50) are also predicted. Based on our calculation, it is confirmed that D1, D2, D5, and E are potential high-energy-density compounds with sufficient stability and excellent detonation performance.</p

Molecular Mechanism of Viscosity Sensitivity in BODIPY Rotors and Application to Motion-Based Fluorescent Sensors

Viscosity in the intracellular microenvironment shows a significant difference in various organelles and is closely related to cellular processes. Such microviscosity in live cells is often mapped and quantified with fluorescent molecular rotors. To enable the rational design of viscosity-sensitive molecular rotors, it is critical to understand their working mechanisms. Herein, we systematically synthesized and investigated two sets of BODIPY-based molecular rotors to study the relationship between intramolecular motions and viscosity sensitivity. Through experimental and computational studies, two conformations (i.e., the planar and butterfly conformations) are found to commonly exist in BODIPY rotors. We demonstrate that the transformation energy barrier from the planar conformation to the butterfly conformation is strongly affected by the molecular structures of BODIPY rotors and plays a critical role in viscosity sensitivity. These findings enable rational structure modifications of BODIPY molecular rotors for highly effective protein detection and recognition

Quaternary Piperazine-Substituted Rhodamines with Enhanced Brightness for Super-Resolution Imaging

Insufficient brightness of fluorophores poses a major bottleneck for the advancement of super-resolution microscopes. Despite being widely used, many rhodamine dyes exhibit sub-optimal brightness due to the formation of twisted intra­molecular charge transfer (TICT) upon photoexcitation. Herein, we have developed a new class of quaternary piperazine-substituted rhodamines with outstanding quantum yields (Φ = 0.93) and superior brightness (ε × Φ = 8.1 × 104 L·mol–1·cm–1), by utilizing the electronic inductive effect to prevent TICT. We have also successfully deployed these rhodamines in the super-resolution imaging of the microtubules of fixed cells and of the cell membrane and lysosomes of live cells. Finally, we demonstrated that this strategy was generalizable to other families of fluorophores, resulting in substantially increased quantum yields

Quaternary Piperazine-Substituted Rhodamines with Enhanced Brightness for Super-Resolution Imaging

Insufficient brightness of fluorophores poses a major bottleneck for the advancement of super-resolution microscopes. Despite being widely used, many rhodamine dyes exhibit sub-optimal brightness due to the formation of twisted intra­molecular charge transfer (TICT) upon photoexcitation. Herein, we have developed a new class of quaternary piperazine-substituted rhodamines with outstanding quantum yields (Φ = 0.93) and superior brightness (ε × Φ = 8.1 × 104 L·mol–1·cm–1), by utilizing the electronic inductive effect to prevent TICT. We have also successfully deployed these rhodamines in the super-resolution imaging of the microtubules of fixed cells and of the cell membrane and lysosomes of live cells. Finally, we demonstrated that this strategy was generalizable to other families of fluorophores, resulting in substantially increased quantum yields

“Crossbreeding” Small-Molecular Weight NIR-II Flavchromenes Endows Activatable Multiplexed In Vivo Imaging

High-performance near-infrared-II (NIR-II) fluorophores have attracted tremendous attention for in vivo dynamic bioimaging. However, the lack of stable, bright, and biocompatible molecular fluorophores becomes a major barrier on the way to the widespread endorsement of NIR-II bioimaging for clinic diagnosis. Here we propose a π-conjugated “crossbreeding” dyad strategy to develop novel desirable NIR-II dyes, flavchromenes (flav+chromene) integrated from two individual fluorophores of flavylium and chromene via a short methine bridge, affording valuable features of extending spectra into the NIR-II region and conferring a substantive leap in the photophysical properties. Notably, these crossbreeding NIR-II dyes have small molecular weights, high molar extinction coefficients, and outstanding chemical stability. As demonstrated, the elaborated probe Flavchrom-4 endows activatable dual-modal in vivo imaging of endogenous β-galactosidase activity, along with lighting-up NIR-II fluorescence signals and dramatically enhanced photoacoustic signals (16.3-fold). This concise π-conjugated crossbreeding dyad strategy brings forth high-performance NIR-II fluorophore scaffolds with small molecular weights, high stability, and good brightness, thus greatly expanding high-resolution activatable in vivo imaging tools for intact tissues and living animals

Quaternary Piperazine-Substituted Rhodamines with Enhanced Brightness for Super-Resolution Imaging

Insufficient brightness of fluorophores poses a major bottleneck for the advancement of super-resolution microscopes. Despite being widely used, many rhodamine dyes exhibit sub-optimal brightness due to the formation of twisted intra­molecular charge transfer (TICT) upon photoexcitation. Herein, we have developed a new class of quaternary piperazine-substituted rhodamines with outstanding quantum yields (Φ = 0.93) and superior brightness (ε × Φ = 8.1 × 104 L·mol–1·cm–1), by utilizing the electronic inductive effect to prevent TICT. We have also successfully deployed these rhodamines in the super-resolution imaging of the microtubules of fixed cells and of the cell membrane and lysosomes of live cells. Finally, we demonstrated that this strategy was generalizable to other families of fluorophores, resulting in substantially increased quantum yields

Unlocking Multicolor Emissions in the Crystalline State through Dimerization and Configurational Transformation of a Single Fluorophore

Multicolor luminescent materials with tunable properties hold great promise for a wide range of applications in materials science. Unfortunately, the conventional approach to achieving multicolor emissions by blending multiple types of fluorophores is hindered by limitations, notably, spectral instability, aggregation-caused quenching, and energy transfer. The pursuit of multicolor emissions from a single type of fluorophore in the solid state has, until now, remained a formidable challenge. In this study, we have introduced N,N′-diphenyl dihydrodibenzo[a,c]-phenazines (DPAC), augmented with two o-carboranyl units, to create a novel fluorophore CbDPAC. The CbDPAC crystal exhibits three distinct emission bands peaking at 405, 470, and 620 nm, respectively, arising from a rich intermolecular interaction network that generates novel emission centers, such as conformational isomers and excimers. This work inspires the rational molecular engineering of smart fluorophores with tailorable properties and inaugurates diverse possibilities for stimuli-responsive luminescent technologies