BODIPY Research Articles

Catalytic Enantioselective Synthesis of Boron‐Stereogenic and Axially Chiral BODIPYs via Rhodium(II)‐Catalyzed C−H (Hetero) Arylation with Diazonaphthoquinones and Diazoindenines

AbstractThe molecular engineering of boron dipyrromethenes (BODIPYs) has garnered widespread attention due to their structural diversity enabling tailored physicochemical properties for optimal applications. However, catalytic enantioselective synthesis of structurally diverse boron‐stereogenic BODIPYs through intermolecular desymmetrization and BODIPYs with atroposelectivity remains elusive. Here, we showcase rhodium(II)‐catalyzed site‐specific C−H (hetero)arylations of prochiral BODIPYs and polysubstituted BODIPYs with diazonaphthoquinonesand diazoindenines, providing efficient pathways for the rapid assembly of versatile (hetero)arylated boron‐stereogenic and axially chiral BODIPYs through long‐range desymmetrization and axial rotational restriction modes. The synthetic application of the procedures has been emphasized by the efficient synthesis of BODIPY derivatives with various functions. Photophysical properties, bioimaging, and lipid droplet‐specific targeting capability of tailored BODIPYs are also demonstrated, indicating their promising applications in biomedical research, medicinal chemistry, and material science.

Catalytic Enantioselective Synthesis of Boron-Stereogenic and Axially Chiral BODIPYs via Rhodium(II)-Catalyzed C-H (Hetero) Arylation with Diazonaphthoquinones and Diazoindenines.

The molecular engineering of boron dipyrromethenes (BODIPYs) has garnered widespread attention due to their structural diversity enabling tailored physicochemical properties for optimal applications. However, catalytic enantioselective synthesis of structurally diverse boron-stereogenic BODIPYs through intermolecular desymmetrization and BODIPYs with atroposelectivity remains elusive. Here, we showcase rhodium(II)-catalyzed site-specific C-H (hetero)arylations of prochiral BODIPYs and polysubstituted BODIPYs with diazonaphthoquinonesand diazoindenines, providing efficient pathways for the rapid assembly of versatile (hetero)arylated boron-stereogenic and axially chiral BODIPYs through long-range desymmetrization and axial rotational restriction modes. The synthetic application of the procedures has been emphasized by the efficient synthesis of BODIPY derivatives with various functions. Photophysical properties, bioimaging, and lipid droplet-specific targeting capability of tailored BODIPYs are also demonstrated, indicating their promising applications in biomedical research, medicinal chemistry, and material science.

Chemically anchored black phosphorus/chromophore composite luminescent materials towards solid-state photoluminescence and electroluminescence

As a promising two-dimensional (2D) material, black phosphorus (BP) has gained great attention because of its intrinsic physicochemical characteristics. However, BP is easy to be oxidized and form various surface defects, which decreases the charge transport and makes luminescence difficult. Herein, we report a facile strategy to synthesize chemically anchored BP/chromophore composite luminescent materials by integrating 2D BP nanosheets with boron dipyrromethene (BODIPY) dyes through simple sonication reactions. Solids of BP composite materials are brightly fluorescent with 5 orders of magnitude increase of photoluminescence intensity compared with the pure solids of BP and BODIPY. 2D BP nanosheets with large specific surface area and lone pair electrons facilitate chemisorption of BODIPY by forming covalent interactions between P and B/N atoms, which not only passivates the surface of BP and eliminates the oxidation, but also prevents the aggregation caused quenching (ACQ) issue of BODIPY. Furtherly, the organic light-emitting diodes (OLEDs) based on the BP/chromophore composite luminescent materials were first successfully achieved, the electroluminescence spectra of which cover the full spectrum of red, green, and blue visible light. This work provides a brand-new approach to further design and development of high mobility and high luminous efficiency composite luminescent materials and devices based on BP.

BODIPY-based fluorescent sensor material for airborne acetone and benzene with aggregation-driven selectivity

Paper highlights advances in design of fluorescent sensors for solvent vapors with boron-dipyrromethene (BODIPY) as a model active component. The present study demonstrates that BODIPY-based fluorescent materials could be successfully utilized for detection of benzene and acetone in gas phase. Concentration of luminophore was found to affect sensory response to benzene (up to 3-fold increase in adjusted conditions). At the same time, sensory response to acetone is concentration-independent, suggesting different underlying response mechanisms and allowing to tune selectivity with choice of concentration. Detection limits achieved for sensory materials are 1.2·104 mg/m3 for acetone and 0.94·104 mg/m3 for benzene. Ultimately, obtained sensor materials could be completely regenerated without need for inert gas purge.

Tetraarylpyrrolo[3,2-b]pyrrole-BODIPY dyad: a molecular rotor for FRET-based viscosity sensing.

With the aim to develop a FRET-based viscosity sensor, two dyad molecules, 4 and 5, comprising tetraarylpyrrolo[3,2-b]pyrrole (TAPP) (donor) and naked boron-dipyrromethene (BODIPY) dyes (acceptor), were designed. Dyads were synthesized via acid-catalyzed multicomponent reactions followed by Sonogashira coupling. In both dyads, the BODIPY and TAPP moieties are linked through phenylethynyl groups, which allow free rotation of the BODIPY dyes; that is, they can act as molecular rotors. This was supported by X-ray crystallographic and DFT-optimized structures. Spectroscopic studies also confirmed the presence of both TAPP and BODIPY dyes in dyads with no electronic interactions that are suitable for fluorescence resonance energy transfer (FRET). Very high energy transfer efficiency (ETE >99%) from the donor TAPP moiety to the acceptor BODIPY moiety on excitation at the TAPP part was observed. However, due to the non-fluorescent nature of naked BODIPY dyes, no fluorescence emission was observed from the BODIPY moiety in both dyads. With increasing solvent viscosities, emission from the BODIPY moieties increases due to the restricted rotation of the BODIPY moieties. Plotting the logarithms of the fluorescent intensity of dyad 5 and the viscosity of the solution showed a good linear correlation obeying a Förster-Hoffmann equation. Non-fluorescent dyad 5 in methanol became greenish-yellow fluorescent in a methanol/glycerol (1:1) solvent. Furthermore, with an increase in the temperature of the methanol/glycerol (1:1) system, as the viscosity decreases, the fluorescence also starts decreasing. Thus, dyad 5 is capable of sensing the viscosity of the medium via a FRET-based "Off-On" mechanism. This type of viscosity sensor with a very large pseudo-Stokes shift and increased sensitivity will be useful for advancing chemo-bio sensing and imaging applications.

Excitation energy transfer based naphthalimide-boron-dipyrromethene dyads as two-photon fluorescent probes for palladium(0) detection and live cell imaging

Increasing industrial demand has accelerated the consumption and contamination of palladium (Pd) worldwide. The implementation of fluorescent probes, especially with two-photon excitation, holds great promise for Pd detection in environmental and biological analysis. In this work, two naphthalimide (NPI)-boron-dipyrromethene (BDP) dyads (named NBH and NBN) were developed as two-photon fluorescent probes for Pd(0) detection based on an excitation energy transfer (EET) strategy, employing NPI as the energy donor and BDP as the acceptor. Spectroscopic studies revealed that both probes exhibited a fast response to Pd(0) in a pronounced fluorescence "ON-OFF" manner. The Pd-catalyzed Tsuji-Trost reaction activated an intramolecular photoinduced electron transfer (PET) process between the aniline and BDP moieties, resulting in the fluorescence quenching of the BDP fluorophore. The reaction-based probes exhibited excellent sensitivity and selectivity for Pd(0) species with a detection limit as low as 2.4 nM. These probes were successfully applied to the determination of Pd residues in drug, soil, and water samples. A simple smartphone-based platform was also constructed to determine Pd(0) via an RGB reader. With negligible cytotoxicity, confocal imaging study validated their feasibility of monitoring Pd(0) in living cells through multiple excitation channels.

Qiwei Jinggan Ling regulates oxidative stress and lipid metabolism in alcoholic liver disease by activating AMPK

BackgroundAlcoholic liver disease (ALD) is a severe public health concern worldwide and there is still a lack of effective treatments. Qiwei Jinggan Ling (QJL) has protective effects against various liver injuries, but its pharmacological action on ALD has received little attention. PurposeTo investigate the effect and mechanism of QJL on ALD in vivo and in vitro. MethodsIn vivo, an ALD mouse model was established by alcohol combined with a high-fat diet (HFD) and treated with QJL. Biochemical indicators, HE staining, and Oil Red O staining were employed to assess hepatic oxidative stress, steatosis, and alcohol metabolism. RNA sequencing analysis was performed, and the results were verified by qRT-PCR and Western blot to elucidate the hepatoprotective mechanism of QJL. In vitro, HepG2 cells were co-stimulated with NaOA (sodium oleate) and EtOH (ethanol), followed by intervention with Compound C (CC, AMPK inhibitor) and QJL-containing serum. Oil Red O, BODIPY (boron-dipyrromethene), and ROS (reactive oxygen species) staining were applied to validate the efficacy and mechanism of QJL-containing serum. The expression of AMP-activated protein kinase (AMPK) pathway-related factors was analyzed through qRT-PCR and Western blot for additional corroboration. Moreover, the key pharmacodynamic components of QJL were identified by UPLC-MS/MS and molecular docking. ResultsIn vivo, QJL ameliorated liver structural disorders, steatosis, oxidative stress, and impaired alcohol metabolism, as indicated by biochemical indicators and histopathological assays. RNA sequencing analysis revealed that QJL reversed the expression of genes related to alcohol metabolism, fatty acid metabolism, and cholesterol metabolism. The results of qRT-PCR and Western blot were in line with those of RNA sequencing. Furthermore, it was discovered that QJL significantly upregulated the expression of p-AMPK and downregulated the expression of sterol regulatory element binding transcription factor 1 (SREBP-1c). In vitro, biochemical indicators and staining assays demonstrated that QJL-containing serum inhibited lipid accumulation and oxidative stress. The qRT-PCR and Western blot analysis revealed that QJL-containing serum markedly enhanced the expression of p-AMPK and carnitine palmitoyltransferase 1a (Cpt1a), while suppressing the expression of SREBP-1c, fatty acid synthase (Fasn), and acetyl-coenzyme A carboxylase 1 (ACC-1). However, CC inhibited the above pharmacological activities of QJL-containing serum. Additionally, (2S)-Liquiritigenin, Glycyrrhetinate, Isovitexin, Taxifolin, and Yohimbine were proved to be the key active components of QJL. ConclusionQJL had the potential to be a therapeutic drug for ALD by activating the AMPK pathway, thereby regulating lipid metabolism and inhibiting oxidative stress.

Simultaneous In Vivo Imaging of Neutrophil Elastase and Oxidative Stress in Atherosclerotic Plaques Using a Unimolecular Photoacoustic Probe.

Atherosclerosis, a major global health concern with high morbidity and mortality rates, involves complex interactions of chronic inflammation, oxidative stress, and proteolytic enzymes. Conventional imaging methods struggle to capture the dynamic biochemical processes in atherosclerotic plaques. Here, we introduce a novel unimolecular photoacoustic probe (UMAPP) designed with specific binding sites for neutrophil elastase (NE) and the redox pair O2⋅-/GSH, enabling real-time monitoring of oxidative stress and activated neutrophils in plaques. UMAPP, comprising a boron-dipyrromethene (BODIPY) core linked to a hydrophilic NE-cleavable tetrapeptide and dual oxidative stress-responsive catechol moieties, facilitates NE-mediated modulation of photoinduced electron transfer impacting photoacoustic intensity at 685 nm (PA685). Furthermore, oxidation and reduction of catechol groups by O2⋅- and GSH induce reversible, ratiometric changes in the photoacoustic spectrum (PA745/PA685 ratio). Initial UMAPP applications successfully distinguished atherosclerotic and healthy mice, evaluated pneumonia's effect on plaque composition and verified the probe's effectiveness in drug-treatment studies by detecting molecular alterations before visible histopathological changes. The integrated molecular imaging capabilities of UMAPP offer promising advancements in atherosclerosis diagnosis and management, enabling early and accurate identification of vulnerable plaques.

Simultaneous In Vivo Imaging of Neutrophil Elastase and Oxidative Stress in Atherosclerotic Plaques Using a Unimolecular Photoacoustic Probe

AbstractAtherosclerosis, a major global health concern with high morbidity and mortality rates, involves complex interactions of chronic inflammation, oxidative stress, and proteolytic enzymes. Conventional imaging methods struggle to capture the dynamic biochemical processes in atherosclerotic plaques. Here, we introduce a novel unimolecular photoacoustic probe (UMAPP) designed with specific binding sites for neutrophil elastase (NE) and the redox pair O2⋅−/GSH, enabling real‐time monitoring of oxidative stress and activated neutrophils in plaques. UMAPP, comprising a boron‐dipyrromethene (BODIPY) core linked to a hydrophilic NE‐cleavable tetrapeptide and dual oxidative stress‐responsive catechol moieties, facilitates NE‐mediated modulation of photoinduced electron transfer impacting photoacoustic intensity at 685 nm (PA685). Furthermore, oxidation and reduction of catechol groups by O2⋅− and GSH induce reversible, ratiometric changes in the photoacoustic spectrum (PA745/PA685 ratio). Initial UMAPP applications successfully distinguished atherosclerotic and healthy mice, evaluated pneumonia‘s effect on plaque composition and verified the probe‘s effectiveness in drug‐treatment studies by detecting molecular alterations before visible histopathological changes. The integrated molecular imaging capabilities of UMAPP offer promising advancements in atherosclerosis diagnosis and management, enabling early and accurate identification of vulnerable plaques.

Formulating the Relationship Between Intermolecular Interactions and Photodynamic Effects Based on the Optical Regularity Exhibited by Rare Earth‐BODIPY Crystalline Frameworks System

AbstractThis research commenced with an exploration of how metal nodes in metal‐organic frameworks (MOFs) influence photodynamic therapy (PDT) outcomes. Ultimately, it is revealed that intermolecular interactions are the core mechanism determining the optical properties and PDT efficacy of MOFs. An advanced system of MOFs based on the integration of twelve rare earth ions (RE3+) with boron dipyrromethene (BODIPY)‐derived ligands is reported. Intriguingly, this series of MOFs exhibits a reverse relationship between the radius of RE3+ and PDT efficacy. Single‐crystal X‐ray diffraction analyses along with theoretical calculations indicate that varying RE3+ results in a spatial displacement of the ligands along the dipole direction, diminishing electrostatic (dipole–dipole) interactions while enhancing dispersion (π–π) interactions, thereby enhancing the generation of triplet excitons. Consequently, a novel parameter, Ae‐v = EvdW / Eint × 100%, is proposed to quantify the interplay between non‐radiative energy dissipation via electrostatic interactions and efficient energy utilization in generating singlet oxygen through dispersion interactions. Furthermore, with consistent acoustic sensitivity aligned with the sonoluminescence mechanism, RE‐DCBs are employed in sono‐photodynamic cancer therapy, attaining significant therapeutic results in tumor treatment during in vivo experiments.

Aldo-Keto reductase 1C3 reduces myocardial cell damage after acute myocardial infarction by activating the Kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor 2-antioxidant response element pathway to inhibit ferroptosis.

Acute myocardial infarction (AMI) is a high-risk cardiovascular condition associated with increased cellular damage and oxidative stress. Aldo-Keto Reductase 1C3 (AKR1C3) is a stress-regulating gene. Nevertheless, its specific role and mechanisms regarding AMI remain unclear. We assessed cardiac function through echocardiography; tissue damage was evaluated using Hematoxylin and Eosin (HE) and Masson trichrome staining. AKR1C3 expression levels were measured through Reverse transcription-quantitative polymerase chain reaction and western blot. Assessed cell viability using Cell Counting Kit-8 and lactate dehydrogenase (LDH) assays. The extent of ferroptosis was determined by measuring the levels of Fe2+, boron-dipyrromethane (BODIPY) and malondialdehyde (MDA), the glutathione/glutathione disulfide (GSH/GSSG) ratio, and the expression of Glutathione Peroxidase 4 (GPX4) and Solute carrier 7A11 (SLC7A11). Kelch-like ECH-associated protein 1-Nuclear factor erythroid 2-related factor 2-Antioxidant response element (Keap1-Nrf2-ARE) pathway activation was analyzed through western blotting. Nrf2 was inhibited with ML385 and activated with (R)-Sulforaphane to investigate the Keap1-Nrf2-ARE pathway. The rats in the AMI group displayed reduced heart function, more tissue damage, and lower AKR1C3 expression compared to the Sham group. Similarly, hypoxia-treated H9C2 cells showed reduced viability, and decreased AKR1C3 expression. Overexpressing AKR1C3 in H9C2 cells enhanced viability. Knocking down AKR1C3 exhibited the opposite effect. Of the inhibitors tested, Ferrostatin-1 most effectively restored cell viability in hypoxia-treated H9C2 cells. Moreover, H9C2 cells subjected to hypoxia suggested Keap1-Nrf2-ARE pathway inhibition. Overexpressing AKR1C3 reduced ferroptosis and activated the Keap1-Nrf2-ARE pathway in hypoxia-treated cells, knocking down AKR1C3 exhibited the opposite effect. Further experiments using ML385 in hypoxia-treated H9C2 cells with overexpressed AKR1C3 showed decreased viability and increased ferroptosis compared to the control. Using (R)-Sulforaphane in hypoxia-treated H9C2 cells with knocked-down AKR1C3 exhibited the opposite effect. This study's findings indicate that AKR1C3 plays a role in regulating ferroptosis in myocardial cells, with the Keap1-Nrf2-ARE pathway likely being a key mechanism behind it.

A nanotheranostics with hypoxia-switchable fluorescence and photothermal effect for hypoxia imaging-guided immunosuppressive tumor microenvironment modulation

Modulating the immunosuppressive tumor immune microenvironment (TIME) is considered a promising strategy for cancer treatment. However, effectively modulating the immunosuppressive TIME within hypoxic zones remains a significant challenge. In this work, we developed a hypoxia-responsive amphiphilic drug carrier using boron-dipyrromethene (BODIPY) dye-modified chitosan (CsB), and then fabricated a hypoxia-targeted nanotheranostic system, named CsBPNs, through self-assembly of CsB and pexidartinib (5-((5-Chloro-1H-pyrrolo[2,3-b]pyridin-3-yl)methyl)-N-((6-(trifluoromethyl)pyridin-3-yl)methyl), PLX3397), an immunotherapeutic drug targeting tumor-associated macrophages (TAMs), for synergistic photothermal/immunotherapy and hypoxia imaging. CsBPNs demonstrated uniform size, good stability, and hypoxia-switchable fluorescence and photothermal effects, enabling deep penetration and hypoxia imaging capacities in three-dimensional tumor cell spheres and tumor tissues. In vitro and in vivo experiments showed that CsBPNs under laser irradiation promoted TAMs repolarization, reversed the immunosuppressive TIME, and enhanced the therapeutic outcome of PLX3397 in solid tumors by facilitating deep delivery into hypoxic regions and synergistic photothermal therapy. This work provides a new strategy for detecting and modulating the immunosuppressive TIME in hypoxic zones, potentially enabling more precise and effective photo-immunotherapy in the future.

β-cyclodextrin-modulated ratiometric supramolecular BODIPY fluoroprobe for highly selective and sensitive detection of thiophenol

Thiophenol (PhSH) is an important industrial intermediate but displays significant toxicity towards environmental and biological systems. Here, we introduce a supramolecular system based on β-cyclodextrin (β-CD) and boron dipyrromethene (BODIPY) as a ratiometric fluorescence probe to discriminate PhSH in environmental water samples, cells, and in vivo. In aqueous solutions, BODIPY shows extremely weak fluorescence intensity due to its aggregation into nanometer-sized clusters, which prevents its interaction with thiols. However, within a β-CD environment, it can selectively and sensitively detect PhSH. Also, the stability of the probe was significantly improved. The mechanism studies based on stoichiometry, NMR spectroscopy, and theoretical calculation revealed distinct intermolecular interactions between β-CD and BODIPY, including host-guest interactions and hydrogen bonds. Low limit of detection (10.7 nM) and rapid response time (5 min) have been achieved, and the practicality of the supramolecular system (BODIPY@β-CD) has been verified by actual sample analysis. Furthermore, the first hydrogel-based sensing system for portable PhSH detection has been developed, facilitating rapid and on-site colorimetric visualization across both liquid and gas phases. Most importantly, using a low amount of the probe, early stages of low-dose exposure to PhSH can be visualized in living cells and zebrafish. Therefore, BODIPY@β-CD is a robust new monitoring tool for the detection of PhSH in various scenarios, indicating the promising application value of the host-guest supramolecular probe in detecting highly toxic substances.

Enhancing Hybrid Photovoltaic-Thermal System Efficiency with Boron Dipyrromethene Dyes.

A library of boron dipyrromethene (BODIPY) compounds was studied to assess their efficacy as components of a working liquid in hybrid photovoltaic-thermal (PVT) systems. Two series of BODIPY dyes were investigated: series I included alkylBODIPYs with varying substitution patterns, while series II included 1,3,5,7-tetramethyl-substituted BODIPYs featuring electron-rich aromatic groups in the meso position, such as naphthalene, anthracene, and carbazole. Series II dyes were designed to exhibit luminescence downshifting due to enhanced UV absorption (300-400 nm) and excited-state energy transfer, leading to visible-region fluorescence under UV excitation. Samples of PVT liquids based on decalin and containing each individual BODIPY dye were tested on a standard a-Si solar cell to evaluate their impact on solar energy conversion efficiency. The thermal behavior of the working liquid and the cell during the illumination cycle was monitored, alongside the cell's electrical characteristics. Energy conversion pathways and the overall effects of the dyes on the system performance were scrutinized. Results indicated that all BODIPY dyes enhanced both the electrical conversion efficiency (up to 2.41% increase) and thermal energy generation (up to 6.87%) compared to the solvent alone. These findings highlight the potential of BODIPY dyes to significantly improve the performance of PVT systems.

Signal-amplified detection of amyloid-β aggregates based on plasmon-enhanced fluorescence

Protein aggregation and misfolding are the main causes of neurodegenerative diseases. The development of a sensitive detection method and early diagnosis is significant for the prevention, diagnosis and treatment of these diseases. Herein, boron dipyrromethene (BODIPY)-modified probe based on plasmon-enhanced fluorescence (PEF) was developed for the detection of amyloid-β protein (Aβ) aggregates. Gold nanoparticles (Au NPs) and BODIPY were as the plasma, fluorescent substance, respectively. Meanwhile, the distance between the Au NPs and the BODIPY was controlled by silica spacer. Compared with the original BODIPY, the fluorescence signal of BODIPY-decorated Au NPs (Au NPs@SiO2-BODIPY) exhibited 13-fold fluorescence enhancement. Three dimensions finite difference time domain (3D-FDTD) result demonstrated the signal-amplified was ascribed to the increase of electric field intensity (3.78 V/m). The linear range and detection limit for Aβ42 detection were lowered to 5–60 μM and 0.85 μM. The developed PEF probe was applied to selective and sensitive recognize Aβ aggregates in mouse colorectal carcinoma cells (CT26) and mouse pancreatic cancer cells (PAN02), which also showed a higher fluorescent signal than the original BODIPY. This method has a broad application prospect in the prediction and detection of neurodegenerative diseases.

Base‐Promoted Regioselective Synthesis of α‐Amino BODIPYs through Cross‐Dehydrogenative Coupling with Anilines

AbstractThe construction of C−N bond at the α‐position of BODIPYs (boron dipyrromethene) not only enables flexible reactivity but also leads to strong electron‐donating properties. In this study, a base‐promoted oxidative cross‐dehydrogenative coupling was developed to synthesize α‐amino BODIPYs with air as a green oxidant. By this strategy, a series of weak nitrogen nucleophiles, such as heteroaryl and aryl anilines, were installed to the α‐position. Remarkably, pyrrole, pyrazole and indole were also employed to realize the synthesis of α‐heteroaryl BODIPYs through direct functionalization. Further aggregation‐induced emission enhancement (AIE) properties and lipid droplet‐targeting bioimaging experiments of representative dyes demonstrated their potential applications as organic probes.

Synthesis, optical properties and self-assemblies of a new halogenated BODIPY dye with long alkoxy chain

A new boron-dipyrromethene (BODIPY) dye modified with two bromine atoms at the 2,6-positions and three hydrophobic p-(dodecyloxy)styryl groups at 3,5,8-positions was designed and synthesized. Its molecular structure was characterized by 1HNMR and MALDI-TOF-MS. The photophysical properties and aggregate behavior of dye 3 in solution were studied by UV–visible absorption and fluorescence spectroscopy. The dye 3 exhibited strong absorption and a high fluorescence quantum yield in different solvents. The self-assembly behaviors were investigated in THF and water mixtures, and the J-aggregates can be formed. Supramolecular self-assembly behavior of dye 3 was confirmed by temperature-dependent UV−Vis absorption. In addition, the self-assembly behavior of dye 3 in liquid-solid interface was studied using scanning tunneling microscopy (STM) and displays highly ordered linear arrangement on HOPG. The self-assembly processes are found to be adjusted by halogen bonding as well as π−π stacking.

Insight into Spectral Properties and Solvatochromic Behavior of [b]‐Fused BODIPYs: Experimental and Computational Study

AbstractTwo π‐extended derivatives of boron‐dipyrromethene (BODIPY) – unsymmetrical benzo[b]‐fused BODIPY 1 and symmetrical naptho[b]‐fused BODIPY 2 – were synthesized. Spectroscopic and photophysical properties of the synthesized fluorescent dyes were investigated in various organic media. Both BODIPY 1 and BODIPY 2 distinguished by bathochromically shifted absorption and emission bands compared to their non‐fused derivatives, while possessing green (526–543 nm) and red (664–708 nm) absorbance and fluorescence, respectively. Spectral characteristics of the investigated fluorescent dyes were found to be weakly depended on solvent polarizability in case of BODIPY 1 and greatly influenced by both solvent polarizability and dipolarity in case of BODIPY 2. Quantum chemical calculations were used to clarify the relationships between geometry/electronic structure and spectral properties/solvatochromic behavior of BODIPY 1 and BODIPY 2.

The vibrational spectra of a model boron dipyrromethene molecule in condensed phase: Experimental and theoretical insights

Boron dipyrromethene (BODIPY) derivatives are an important class of organic molecular dyes. Their chemical structure can be easily modified by synthetic methods, introducing various substituent groups on a tricyclic core that represents the characteristic unit of these compounds. As a consequence, BODIPY optical properties can be designed to tune their absorption and emission in an especially wide wavelength range. A large amount of experimental and computational studies has been performed to investigate the electronic excited states of many structurally different BODIPY dyes. On the other hand, vibrational properties are by far less known for these compounds. We have therefore measured detailed infrared and Raman spectra of a model compound, namely, a BODIPY derivative with four methyl groups and a phenyl ring as substituents. The experimental spectra of the solid sample have been contrasted with ab initio spectra computed at the CAM-B3LYP/6-31G+(d) level. Computations have been performed both for the isolated molecule and including the crystalline environment. In the latter case, better agreement has been observed. An assignment is proposed for the 123 vibrational modes. These results form the basis for further spectroscopic studies on complex BODIPY derivatives.

Molecular Engineering of a Doubly Quenched Fluorescent Probe Enables Ultrasensitive Detection of Biothiols in Highly Diluted Plasma and High-Fidelity Imaging of Dihydroartemisinin-Induced Ferroptosis.

The occurrence and development of diseases are accompanied by abnormal activity or concentration of biomarkers in cells, tissues, and blood. However, the insufficient sensitivity and accuracy of the available fluorescence probes hinder the precise monitoring of associated indexes in biological systems, which is generally due to the high probe intrinsic fluorescence and false-negative signal caused by the reactive oxygen species (ROS)-induced probe decomposition. To resolve these problems, we have engineered a ROS-stable, meso-carboxylate boron dipyrromethene (BODIPY)-based fluorescent probe, which displays quite a low background fluorescence due to the doubly quenched intrinsic fluorescence by a combined strategy of the photoinduced electron transfer (PET) effect and "ester-to-carboxylate" conversion. The probe achieved a high S/N ratio with ultrasensitivity and good selectivity toward biothiols, endowing its fast detection capability toward the biothiol level in 200×-diluted plasma samples. Using this probe, we achieved remarkable distinguishing of liver injury plasma from normal plasma even at 80× dilution. Moreover, owing to its good stability toward ROS, the probe was successfully employed for high-fidelity imaging of the negative fluctuation of the biothiol level in nonsmall-cell lung cancer (NSCLC) during dihydroartemisinin-induced ferroptosis. This delicate design of suppressing intrinsic fluorescence reveals insights into enhancing the sensitivity and accuracy of fluorescent probes toward the detection and imaging of biomarkers in the occurrence and development of diseases.