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A meso -BODIPY-type photoremovable protecting group for carboxyl group is developed. BODIPYs are well-known for brilliant color, favorable to reaction monitoring and purification. meso -BODIPY esters are achieved via esterification in 44–89% yields, while deprotection is fulfilled under irradiation of blue LED bulb in the presence of photocatalyst and organic hydrogen donor in 43–95% yields. This method is applicable to a variety of acids, such as aromatic, heteroaromatic, alkyl, α,β-unsaturated carboxylic acids, etc. Our BODIPY-deprotective condition is almost neutral that both methyl and tert -butyl esters are compatible. [ABSTRACT FROM AUTHOR]

Immunotherapy, a pivotal and promising approach for tumor treatment, has demonstrated prominent clinical efficacy. However, its effectiveness is often impeded by insufficient antitumor immune responses attributed to the immunosuppressive tumor microenvironment (TME). The combination of immune activation through the stimulator of interferon genes (STING) pathway and phototherapy holds great potential for surmounting this challenge in advanced tumor immunotherapy. Herein, a novel manganese-boosted NIR-II photo-metalloimmunotherapy is proposed to synergistically enhance antitumour efficacy by fabricating Mn2+-BODIPY-based coordinated photo-immune nanoadjuvants (BMR), modified with tumor-targeted peptide cRGD. The obtained BMR could effectively deliver Mn2+ to tumor sites, and immunogenic cell death (ICD) was evoked by localized photothermal ablation of tumors using NIR-II laser irradiation. Simultaneously, pH-responsive release of Mn2+ would trigger the activation of STING pathway to promote the production of type I interferons (I-IFNs), significantly facilitating the maturation of dendritic cells (DCs) and polarization of macrophages to M1 phenotypes. Furthermore, by synergistically initiating systematic and robust antitumour immune responses, the BMR-mediated NIR-II photo-metalloimmunotherapy achieved remarkable therapeutic efficacy against both primary and lung metastasis of B16F10 tumors. Overall, in light of the versatile functionalities and synthetic flexibility of coordinated nanoadjuvants, formulated with photofunctional ligands and diverse metal ions, this work provides new insights into the design of metal coordination nanomedicine for effective antitumor photo-metalloimmunotherapy. [Display omitted] [ABSTRACT FROM AUTHOR]

New polymorphs of (2-(chloro(pyrrol-2-ylidene)methyl)pyrrole)-difluoro-borane (1) and (2-(chloro(4-ethyl-3,5-dimethyl-2H-pyrrol-2-ylidene)methyl)pyrrole)-4-ethyl-3,5-dimethyl-1H-pyrrolato)-difluoro-borane (2) were identified using single crystal X-ray diffraction. The new polymorph of 1 crystallises in the triclinic, P-1 space group with an asymmetric unit comprising two crystallographically-independent molecules (Z′ = 2). The differences between this structure and that of the known polymorph of 1 are attributed to the formation of two distinct dimer motifs in each polymorph and the packing between these dimer units. The new polymorph structure of 2, exhibits a similar asymmetric unit to the known form, comprising 3 molecules (Zʹ = 3). The two structures differ in the orientation of the molecules within the trimeric asymmetric unit and the manner in which these trimers pack along the crystallographic [010] direction. The triclinic polymorph of 8-chloro BODIPY exhibits an asymmetric unit with two crystallographically-independent molecules. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, glycerol, glycosyl, and tetraethyleneglycol monomethyl ether group substituted BODIPY compounds were successfully synthesized and characterized. The antioxidant, antidiabetic, antibiofilm, microbial cell viability, antimicrobial, antimicrobial photodynamic therapy, and DNA cleavage abilities of the BODIPY derivates were also tested. The highest antioxidant activity at 100 mg/L was 87.12% for BODIPY‐1, 85.61% for BODIPY‐2, and 92.78% for BODIPY‐3. The most effective inhibition of microbial cell viability was obtained for these BODIPY molecules at 100% at 50 and 100 mg/L. It was also observed that these BODIPY molecules exhibited excellent biofilm inhibition activities. The derivates were found to exhibit higher antibiofilm abilities against Staphylococcus aureus compared to Pseudomonas aeruginosa. When the antidiabetic effects of water‐soluble BODIPY compounds were examined, the highest effect was found to be 64.40% for BODIPY‐1 at 200 mg/L. [ABSTRACT FROM AUTHOR]

Icosahedral boron clusters-based BODIPY dyes represent a cutting-edge class of compounds that merge the unique properties of boron clusters with the exceptional fluorescence characteristics of BODIPY dyes. These kinds of molecules have garnered substantial interest due to their potential applications across various fields, mainly including optoelectronics, bioimaging, and potential use as boron carriers for Boron Neutron Capture Therapy (BNCT). Carborane clusters are known for their exceptional stability, rigid geometry, and 3D-aromaticity, while BODIPY dyes are renowned for their strong absorption, high fluorescence quantum yields, and photostability. The integration of carborane into BODIPY structures leverages the stability and versatility of carboranes while enhancing the photophysical properties of BODIPY-based fluorophores. This review explores the synthesis and structural diversity of boron clusters-based BODIPY dyes, highlighting how carborane incorporation can lead to significant changes in the electronic and optical properties of the dyes. We discuss the enhanced photophysical characteristics, such as red-shifted absorption and emission poperties, charge and electronic transfer effects, and improved cellular uptake, resulting from carborane substitution. The review also delves into the diverse applications of these compounds. In bioimaging, carborane-BODIPY dyes offer superior fluorescence properties and cellular internalization, making them ideal for cell tracking. In photodynamic therapy, (PDT) these dyes can act as potent photosensitizers capable of generating reactive oxygen species (ROS) for targeted cancer treatment making them excellent candidates for PDT. Additionally, their unique electronic properties make them suitable candidates for optoelectronic applications, including organic light-emitting diodes (OLEDs) and sensors. Overall, carborane-BODIPY dyes represent a versatile and promising class of materials with significant potential for innovation in scientific and technological applications. This review aims to provide a comprehensive overview of the current state of research on carborane-BODIPY dyes, highlighting their synthesis, properties, and broad application spectrum. [ABSTRACT FROM AUTHOR]

Synthesis, photochemical properties, liposomal encapsulation, and in vitro photodynamic activity studies of novel BODIPY dimer connected at meso-meso positions and its brominated and iodinated analogs were described. UV-Vis measurements indicated that the dimeric structure of obtained BODIPYs did not significantly influence the positions of the absorption maxima. Emission properties and singlet oxygen generation studies revealed a strong heavy atom effect of brominated and iodinated BODIPY dimers, manifested by fluorescence intensity reduction and increased singlet oxygen generation ability compared to analog without halogen atoms. For the in vitro photodynamic activity studies, dimers were incorporated into two different types of liposomes: positively charged DOTAP:POPC and negatively charged POPG:POPC. The photoinactivation studies revealed high activity of brominated and iodinated dimers incorporated into DOTAP:POPC liposomes on both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. Anticancer studies on human breast adenocarcinoma MDA-MB-231 and human ovarian carcinoma A2780 cells revealed that DOTAP:POPC liposomes containing brominated and iodinated dimers were active even at low nanomolar concentrations. In addition, they were more active against MDA-MB-231 cells than A2780 cells, which is particularly important since the MDA-MB-231 cell line represents triple-negative breast cancer, which has limited therapeutic options. [ABSTRACT FROM AUTHOR]

Tris(3‐pyrrolyl BODIPY) on 1,3,5‐triazine scaffold was synthesized over a sequence of steps starting from commercially available cyanuric chloride. The cyanuric chloride was reacted with p‐hydroxy benzaldehyde to afford 1,3,5‐triazine tris(p‐oxybenzaldehyde) which was then reacted with excess pyrrole under acid catalyzed conditions to afford 1,3,5‐triazine‐tris(meso‐p‐oxyphenyl dipyrromethane). Subsequent in situ oxidation of this compound with DDQ to obtain tris(meso‐oxyphenyldipyrromethene) which was then treated with pyrrole followed by the addition of Et3N/BF3 ⋅ OEt2 afforded fluorescent tris(3‐pyrrolyl BODIPY). For comparison, tris(BODIPY) on the triazine scaffold was prepared by oxidizing tris(meso‐oxyphenyldipyrromethane) with DDQ followed by complexation with BF3 ⋅ OEt2. Both compounds were thoroughly characterized and studied by various experimental and theoretical methods. Absorption, steady state fluorescence, time‐resolved fluorescence, and transient‐absorption studies revealed that in tris(3‐pyrrolyl BODIPY), excitonic interactions between two of the three 3‐pyrrolyl BODIPY units resulted in a hypsochromic shift in spectral bands, reducing the quantum yield and singlet state lifetime whereas tris(BODIPY) did not show such excitonic interactions. DFT studies helped in understanding the excitonic interactions in tris(3‐pyrrolyl BODIPY). The tris(3‐pyrrolyl BODIPY) was fluorescent both in solution and solid state. The viscosity studies indicated that the fluorescence of tris(3‐pyrrolyl BODIPY) increases significantly with solvent viscosity, suggesting its potential for measuring cellular viscosity during physiological processes. [ABSTRACT FROM AUTHOR]

Optical monitoring of peptide binding to live cells is hampered by the abundance of naturally occurring fluorophores such as tryptophan. Unnatural amino acids incorporating synthetic fluorophores such as BODIPY overcome these optical limitations. A drawback to using fluorophores in lipid binding peptide design is their propensity to override other interactions, potentially causing the peptides to lose their binding selectivity. Here, the binding strength of a selection of peptides incorporating a variety of BODIPY derivatized amino acids has been studied via molecular dynamics simulations to quantify the impact of BODIPY incorporation on peptide-membrane binding behaviour. [ABSTRACT FROM AUTHOR]

We present a highly sensitive and selective fluorescence “turn‐on” sensor for l‐histidine (His) detection in aqueous solutions utilizing a 1‐Cu2+ complex. This sensing platform employs a fluorescence‐based ligand displacement approach, featuring a meso‐(N’‐acetyl‐hydrizide)‐based BODIPY derivative (1) complexed with Cu2+. Initially highly fluorescent, compound 1 is selectively quenched by Cu2+ ions, forming the 1‐Cu2+ complex. The high affinity between His and Cu2+ effectively displaces 1 from the complex, restoring fluorescence. The system exhibits rapid response (within 5 minutes), excellent sensitivity (detection limit of 78 nM), operational simplicity, and a large fluorescence “turn‐on” signal. It demonstrates remarkable selectivity for His over other amino acids, with maleimide masking cysteine interference. Notably stable in complex biological matrices, the sensor has successfully quantified His in artificial urine samples. Its practical applicability extends to paper‐based test strips, offering portability and potential for real‐time His monitoring in clinical diagnostics and biological systems. [ABSTRACT FROM AUTHOR]

BODIPYs have a well‐established role in biological sciences as chemosensors and versatile biological markers due to their chemical reactivity, which allows for fine‐tuning of their photophysical characteristics. In this work, we combined the unique reactivity of arylazo sulfones with the advantages of a "sunflow" reactor to develop a fast, efficient, and versatile method for the photochemical arylation of BODIPYs and other chromophores. This approach resulted in red‐shifted emitting fluorophores due to extended electronic delocalization at the 3‐ and 5‐positions of the BODIPY core. This method represents an advantageous approach for BODIPY functionalization compared to existing strategies. [ABSTRACT FROM AUTHOR]

Creating innovative catalysts utilizing nonprecious metals for the electrocatalytic hydrogen evolution reaction (HER) poses a significant difficulty. We present a cobaloxime (Cox) complex having pyridine (2-Cox) and tetrafluorophenyl-thio-pyridine (4-Cox) functional groups, which contains a 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) moiety. This combination serves as a catalyst for proton reduction and is immobilized onto reduced graphene oxide (rGO) by π–π stacking between the cobaloxime complex and rGO. Moreover, the unique complex's structures were determined through the application of ultraviolet–visible spectroscopy (UV–Vis), Fourier Transform Infrared spectroscopy (FT-IR), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM). The electrocatalytic activity of the two rGO/2-Cox and rGO/4-Cox electrodes towards hydrogen (H 2) were examined under both alkaline and acidic conditions. The cobaloxime-modified rGO electrodes demonstrate superior electrocatalytic performance for the HER under acidic conditions compared to alkaline conditions. The overpotential at a current density of 10 mA cm−2 for rGO/2-Cox in 0.5 M H 2 SO 4 is −0.342 V, which is notably lower than the overpotential of rGO/4-Cox (−0.496 V). The Tafel slope for the rGO/2-Cox electrode in a 0.5 M H 2 SO 4 solution is 111 mV.dec−1, but for the rGO/4-Cox electrode it is 156 mVdec−1. This discrepancy suggests that the rGO/2-Cox electrode demonstrates better performance in the HER compared to the rGO/4-Cox electrode. • Two different BODIPY-cobaloxime complexes were synthesized. • These combinations are immobilized on reduced graphene oxide by π-π stacking. • The electrocatalytic activity of these structures towards hydrogen was studied. • 2-Cox structure exhibited superior electrocatalytic performance for HER. • These catalysts have the potential to be used in various energy applications. [ABSTRACT FROM AUTHOR]

We report on the synthesis of two new threaded BODIPYs 5 and 6 in good yields using boron as a gathering atom and a macrocycle with a 2,2'‐biphenol unit. In addition to usual techniques, they were characterized by X‐ray crystallography. Their electrochemical and optical properties were investigated. In particular, both compounds are highly emissive with photoluminescence quantum yields of 54 and 81 % respectively. In addition, they both show a high photostability. [ABSTRACT FROM AUTHOR]

The design, synthesis, and characterization of novel BODPY‐based iridium and ruthenium complexes were reported. The structures of new compounds were fully characterized by FT‐IR, MALDI‐TOF mass analysis, elemental analysis, 1H, and 19F NMR spectroscopies. Precursor BODIPY was characterized by single‐crystal x‐ray diffraction technique for the first time. Photophysical properties including absorption and emission profiles and lifetimes were investigated via UV–vis absorption and emission spectroscopy. Photochemical properties were investigated via direct method, and the singlet oxygen production capabilities of new complexes were determined by NIR phosphorescence methods. BODIPY‐based new complexes were efficient at producing 1O2. Besides, both complexes showed more remarkable photosensitization ability than some commonly used photosensitizer based on BODIPY derivatives. This study points out that novel complexes are effective 1O2 photosensitizers that might be used for different application areas like photodynamic therapy. [ABSTRACT FROM AUTHOR]

A series of seven new meso -phenyl BODIPY-pyrrolo[3,4- b ]pyridin-5-one conjugates were synthesized in one experimental step by using a Sc(III)-catalyzed Ugi-Zhu three-component reaction coupled to a cascade sequence (aza Diels-Alder/ N -acylation/aromatization) as post-MCR functionalization process. Further experimental studies were performed behind understanding the fluorescence response toward viscosity. All compounds exhibited a linear response between increasing viscosity (DMSO and glycerol mixtures) and fluorescence intensity. The different substituents also influenced the photophysical properties. Furthermore, in DMSO all compounds exhibited dual emission. Each band is attributed to the pyrrolo[3,4- b ]pyridin-5-one and BODIPY moieties, respectively. The electronic structure of all compounds was computed by DFT and TD-DFT calculations, allowing to determine the molecular orbitals involved in the electronic transitions. [ABSTRACT FROM AUTHOR]

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. Nonfluorescent 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. [ABSTRACT FROM AUTHOR]

Organic light‐emitting diodes (OLEDs) using a simple solution‐processing approach have natural advantages in cost‐effective commercialization. However, solution‐processed deep‐red OLEDs are rarely reported due to the scarcity of efficient purely organic narrowband red emitters with commendable film‐forming capabilities. Herein, a simple strategy is proposed to develop organic molecules with narrowband red emission by expanding a rigid conjugated frame to block the rotation of α position in the boron‐dipyrromethene (BODIPY) core due to restricted twisting vibration. Furtherly, by introducing a moderate donor to the meso‐position of the BODIPY core, bathochromic‐shifted emission can be achieved without sacrificing narrow full‐width at half‐maximum (FWHM) by increasing the electron density of the whole molecule and repulsive force of distal units to suppress stretching/scissoring vibration. By employing the developed BODIPY‐derived materials as terminal emitters and thermally activated delayed fluorescence material as assistant host to fabricate solution‐processed OLED devices, a maximum external quantum efficiency of 16.43% is achieved with an emission peak at 672 nm and a FWHM of 28 nm. This work, according to the knowledge, represents the best instance of solution‐processed deep‐red narrowband OLEDs based on typical fluorescent emitters. [ABSTRACT FROM AUTHOR]

We have synthesized two dyads (dyad 1 and 2) comprising of tetraarylpyrrolo[3,2‐b]pyrrole (TAPP) and BODIPY. In dyad 1, two BODIPYs are directly connected with TAPP moiety whereas in dyad 2, BODIPYs are connected through phenylethynyl linkers. TAPP is a blue energy donor which is easy to synthesize and functionalize as compared to other well‐known blue energy donors like pyrene, perylene etc. This is the first report of using TAPP as an energy donor in BODIPY based dyad molecules. Complete quenching of TAPP fluorescence in the dyads suggests fast energy transfer from TAPP to BODIPY unit (ETE~99.9 %). Ultrafast fluorescence and transient absorption spectroscopic studies of dyad 1 showed TAPP to BODIPY energy transfer in 125 fs (kET=8.0×1012 s−1) which is one of the fastest energy transfer events in BODIPY based dyad reported so far. Whereas, in dyad 2, energy transfer is almost four times slower (480 fs, kET=2.1×1012 s−1). These results were rationalized by theoretical Förster formulations. This study shows that suitably matched optical properties of TAPP and BODIPY dyes along with their easy syntheses will be the key to develop highly efficient energy transfer systems in future for multiple applications. [ABSTRACT FROM AUTHOR]

The uptake and phototoxicity of a family of BODIPY‐perylene charge transfer dyads are compared in live cancer and non‐cancer cell lines to evaluate their performance in imaging and photodynamic therapy (PDT). The impact of iodination and mesylation of the meso position of the compounds on their optical properties, cell uptake and toxicity are compared. Notably, across all derivatives the probes were minimally dark toxic up to 50 μM, (the maximum concentration tested), but exhibited outstanding phototoxicity with nanomolar IC50 values and impressive phototoxic indices (PI, ratio of dark IC50 to light IC50), with best performance for the mesylated iodinated derivative MB2PI, which had a PI of >218 and >8.9 in MCF‐7 cells and tumour spheroids respectively. This is significantly higher than non‐iodinated analogue MB2P in MCF‐7 cells with an observed PI of >109 and slightly higher than MB2PI in spheroids with a PI of >8. This compound also showed interesting emission spectral variation with localisation that responded to stimulation of inflammation. Additional studies confirmed efficient singlet oxygen generation by the BODIPYs, suggesting a Type II mechanism of phototoxicity. Overall, the data indicates that combining charge transfer and iodination is an effective strategy for enhancing phototherapeutic capacity of BODIPY PS. [ABSTRACT FROM AUTHOR]

Nowadays homogeneous germanium (Ge) pyramid arrays are emerging in many application areas such as solar cells, photodetectors and next-generation semiconductor lasers. To enhance the application areas of germanium pyramid surfaces, particularly in chemical and biological sensors, these surfaces need to be modified to rapidly respond to biological molecules. In this work, a simple and costeffective method was investigated to modify germanium pyramid surfaces with 3-aminopropyltriethoxysilane (APTES), enabling them to be functionalized for interaction with biological molecules. In order to establish the presence of APTES on germanium surfaces, APTES modified surfaces were labeled with fluorescent BODIPY molecules. During the silanization process, the effects of reaction time and reaction temperature were studied for the attachment of APTES on bulk germanium and pyramid array. The products of different reactions were characterized using photoluminescence spectroscopy (PL) and fluorescence lifetime imaging microscopy (FLIM). The optimum reaction time and processing temperature for a reasonably good surface coverage by APTES molecules were determined as 24 hour and 60 0C, respectively. The fluorescence lifetime of BODIPY molecules on pyramids monitored with FLIM microscope was measured as 2.4 ns. APTES treatment can offer a robust and reliable pathway to immobilize various molecules on electronically important semiconductor surfaces and fabricate new optoelectronic devices with high performance. [ABSTRACT FROM AUTHOR]

Abstract Optical monitoring of peptide binding to live cells is hampered by the abundance of naturally occurring fluorophores such as tryptophan. Unnatural amino acids incorporating synthetic fluorophores such as BODIPY overcome these optical limitations. A drawback to using fluorophores in lipid binding peptide design is their propensity to override other interactions, potentially causing the peptides to lose their binding selectivity. Here, the binding strength of a selection of peptides incorporating a variety of BODIPY derivatized amino acids has been studied via molecular dynamics simulations to quantify the impact of BODIPY incorporation on peptide-membrane binding behaviour.

[Display omitted] 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. [ABSTRACT FROM AUTHOR]

This study explored the synthesis and application of BODIPY-functionalized gold nanoparticles (AuNPs) for the sensitive detection of biothiols via an indicator displacement assay coupled with surface-enhanced Raman scattering (SERS) techniques, alongside their efficacy for in vitro cancer cell imaging. Moreover, the assay allowed for the visible colorimetric detection of biothiols under normal and ultraviolet light conditions. The BODIPY (boron-dipyrromethene) fluorophores were strategically conjugated to the surface of gold nanoparticles, forming a robust nanohybrid that leverages the plasmonic properties of AuNPs for enhanced spectroscopic sensitivity. The detection mechanism exploited the displacement of the BODIPY indicator upon interaction with biothiols, triggering a measurable change in fluorescence and SERS signals. This dual-mode sensing approach provides high selectivity and sensitivity for biothiol detection, with detection limits reaching nanomolar concentrations using fluorescence and femtomolar concentration for cysteine using SERS. Furthermore, the BODIPY-AuNP complexes demonstrated excellent biocompatibility and photostability, facilitating their use in the fluorescence imaging of biothiol presence within cellular environments and highlighting their potential for diagnostic and therapeutic applications in biomedical research.

This 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. [ABSTRACT FROM AUTHOR]

The increasing resistance of bacterial pathogens to antibiotics poses serious threats to public health, exacerbating the challenge of treating infectious diseases. Antibacterial materials that integrate two or more therapeutic modalities concurrently have emerged as a viable alternative strategy to combat pathogenic bacteria. In this study, a postmethylation approach was employed to significantly enhance the photothermal and photodynamic activity of a photoactive antibacterial agent simultaneously. Using this method, a cationic covalent organic framework (COF) nanostructure, named IPB-COF, was easily fabricated through the postmethylation of a BODIPY-based COF obtained via the polycondensation of piperazine and dialdehyde-BODIPY through an aminal linkage. Besides improving the photothermal and photodynamic activities, the postmethylation also led to the formation of built-in quaternary ammonium cations, enhancing the adhesion capacity with bacteria. The resulting IPB-COF nanostructures exhibited enhanced synergistic photothermal and photodynamic therapeutic capabilities against both Gram-positive and Gram-negative bacteria upon visible light irradiation. It achieved rapid sterilization with an approximately 100% bactericidal ratio at a low dosage, significantly higher than that of the unmethylated sample (PB-COF). Additionally, in vivo assays demonstrated that IPB-COF nanostructures also possessed high efficiency and safe wound disinfection capacities, significantly accelerating the healing of infected wounds. Overall, this study proposes a simple yet robust method for the tunable preparation of COF-based antibacterial agents that can rapidly, safely, and synergistically combat pathogenic bacteria infections, circumventing antibiotic resistance. [ABSTRACT FROM AUTHOR]

To develop heavy‐atom‐free triplet photosensitizers (PSs) based photocatalysts, we designed and synthesized two BODIPY‐helicene dyes by fusing the BODIPY core and modified [5]helicene structures. These BODIPY‐helicenes structures are twisted and their twisting angles are increased by the developed synthetic method. The BODIPY‐helicenes have broad absorption bands over UV‐visible region with high triplet conversions and long triplet lifetimes as compared to planar BODIPY dye, PM567. Consequently, these dyes are also highly efficient in generating 1O2 by transferring their triplet energy to 3O2. All these are confirmed by dye‐sensitised photooxidation reaction, nanosecond transient absorption spectroscopy study, phosphorescence measurement and DFT calculations. Finally, photocatalytic activity of the highest 1O2 generating BODIPY‐helicene (4 b) was checked. 4 b is highly efficient in photocatalytic oxidative coupling of differently substituted amines through aerobatic oxidation using 1O2 generated by its photosensitization. It is also highly efficient photocatalyst for aerobatic oxidation of sulfides to sulfoxides. Importantly, the photocatalyst could be quantitatively recovered and reused for several cycles. All these results confirmed the potential use of the BODIPY‐helicenes as PSs for photocatalytic organic reactions and the design strategy will be useful for the future development of heavy‐atom‐free photocatalyst. [ABSTRACT FROM AUTHOR]

We synthesized ridaifen-B boron dipyrromethene (RID-B-BODIPY) using 2methyl-6-nitro benzoic anhydride (MNBA)-mediated dehydration condensation reaction between amino alkyl-tethered RID and BODIPY FL. Comparative experiments between dicyclohexylcarbodiimide (DCC) and MNBA for their coupling reactions demonstrated that MNBA is an effective condensation reagent for amines and BODIPY FL. A cell staining study with RID-B-BODIPY showed intracellular localization of BODIPY FL fluorescence, attributed to the RID-B structure, indicating the successful development of a tool for analyzing intracellular molecular behavior efficiently. [ABSTRACT FROM AUTHOR]

Fluorescence imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) has aroused immense attention for biomedical applications, offering exceptional advantages such as ultra‐low photon scattering and increased tissue penetration. Among the NIR‐II‐emitted organic dyes, Boron dipyrromethene (BODIPY), has emerged as a noteworthy candidate. BODIPY, distinguished by its controllable molecular structure and optical properties, outstanding fluorescence quantum yields, high molar absorption coefficients, and remarkable chemical stability, has undergone comprehensive investigation and extensive exploration within the realm of biological theranostics. This work aims to provide a comprehensive summary of the advancements in the development and design strategies of NIR‐II BODIPY fluorophores tailored for advanced biological phototheranostics. Initially, the work elucidates several representative and controllable strategies, concluding the electron‐programming strategy, extension of the conjugated backbone, J‐aggregation strategy, and strategic establishment of activatable fluorophores, which enhance the NIR‐II fluorescence of BODIPY skeletons. Subsequently, developments in NIR‐II fluorescent BODIPY‐based nanoplatforms for biological applications are intricately elaborated. In conclusion, this work outlines future efforts and directions for refining NIR‐II BODIPY to meet evolving clinical demands. It is anticipated that this contribution may provide a feasible reference for the strategic design of organic NIR‐II fluorophores, thereby advancing their potential in future clinical practices. [ABSTRACT FROM AUTHOR]

Molecular organic photocatalysts developed for use in chemical transformation reactions have gained momentum in recent years. In this study, six new triplet photosensitizers were prepared to determine their photocatalyst capabilities and chemical transformation abilities. The chemical structures of the synthesized orthogonal BODIPYs and their cyclotriphosphazene derivatives were analyzed and then their photophysical characteristics including the UV‐Vis absorption spectra, fluorescence emission spectra, fluorescence quantum yields, were investigated. The quantitative singlet oxygen formation was determined by chemical trapping using DPBF (diphenylisobenzofuran). In particular, cyclotriphosphazene derivative 12 having three BODIPY moieties showed efficient singlet oxygen production with high photostability and good molar extinction coefficient. The photo‐oxidation ratio constant of 1,5‐dihydroxynaphthalene (DHN) was calculated as 28.7×10−3 min−1 for compound 12 and at the end of 22.5 min., DHN converted to juglone with 100 % efficiency. In addition, the ability of the compounds to convert 1,3‐cyclohexadiene into peroxides in the presence of molecular oxygen and light was investigated and the conversion efficiency was determined by NMR technique. All compounds have been presented as photocatalysts for use in different synthetic photochemistry applications. [ABSTRACT FROM AUTHOR]

This study explored the synthesis and application of BODIPY-functionalized gold nanoparticles (AuNPs) for the sensitive detection of biothiols via an indicator displacement assay coupled with surface-enhanced Raman scattering (SERS) techniques, alongside their efficacy for in vitro cancer cell imaging. Moreover, the assay allowed for the visible colorimetric detection of biothiols under normal and ultraviolet light conditions. The BODIPY (boron-dipyrromethene) fluorophores were strategically conjugated to the surface of gold nanoparticles, forming a robust nanohybrid that leverages the plasmonic properties of AuNPs for enhanced spectroscopic sensitivity. The detection mechanism exploited the displacement of the BODIPY indicator upon interaction with biothiols, triggering a measurable change in fluorescence and SERS signals. This dual-mode sensing approach provides high selectivity and sensitivity for biothiol detection, with detection limits reaching nanomolar concentrations using fluorescence and femtomolar concentration for cysteine using SERS. Furthermore, the BODIPY-AuNP complexes demonstrated excellent biocompatibility and photostability, facilitating their use in the fluorescence imaging of biothiol presence within cellular environments and highlighting their potential for diagnostic and therapeutic applications in biomedical research. [ABSTRACT FROM AUTHOR]

A modular synthesis of novel series of 1,7‐difluorinated BODIPYs has been elaborated. First, the acid‐catalyzed condensation of ethyl 3‐aryl‐4‐fluoro‐1H‐pyrrole‐2‐carboxylates with aromatic aldehydes gives the corresponding dipyrromethane‐1,9‐dicarboxylates. The latter are subjected to the exhaustive reduction with lithium aluminum hydride to transform the ester moieties into methyl groups. The subsequent oxidation of the resulting 1,9‐dimethylated dipyrromethanes followed by the boron difluoride complexation afforded a family of novel core‐fluorinated BODIPYs in up to 74 % yield. Photophysical properties of the resulting BODIPYs were tuned by varying of the starting fluoropyrroles and aromatic aldehydes and were studied by UV‐visible and fluorescence spectroscopy. As a result, the fluorescence quantum yields of the obtained compounds reached up to 99 %. In addition, their ability to generate singlet oxygen and electrochemical properties were also evaluated. As a result, a new promising family of fluorophores with a good combination of the fluorescence and photosensitizing properties was obtained. It was found that conversion of ester groups into methyl ones at the 3,5‐positions of the BODIPY core is a crucial step toward fluorescence enhancement. In addition, DFT calculations were performed to elucidate a relationship between electronic structure, geometry and photophysical properties of these BODIPYs. [ABSTRACT FROM AUTHOR]

Sonodynamic therapy (SDT) has demonstrated significant potential in addressing multidrug‐resistant bacterial infections due to its noninvasive nature and independence from antibiotics and light sources. However, the majority of current sonosensitizers exhibit aggregation‐caused quenching (ACQ), leading to low reactive oxygen species (ROS) generation efficiency. Herein, a novel nonplanar structured sonodynamic (4,4‐difluoro‐4‐boron‐3a,4‐diaza‐indandiene) BODIPY derivative, BODN, with aggregation‐induced emission (AIE) properties, and rapid generation of substantial ROS by ultrasound is introduced. The BODN is co‐assembled with the commercial amphiphilic polymer, mDSPE‐PEG2000, forming BODN nanoparticles (BODN‐NP). Under ultrasound conditions, BODN‐NP demonstrates potent antimicrobial activity and improves the inflammatory response to promote healing wounds infected by both Staphylococcus aureus and methicillin‐resistant Staphylococcus aureus. This work expands the use of AIE sonodynamic materials in antimicrobial therapy and provides new perspectives for innovative solutions against multidrug‐resistant bacterial infections. [ABSTRACT FROM AUTHOR]

We report herein an effective method for an iron‐catalyzed vinylogous Michael addition of BODIPY derivatives to para‐quinone methides under mild conditions. The corresponding BODIPY‐derived diarylmethane compounds were obtained in 65–93 % yields. This method is featured by its inexpensive catalyst, simple reaction condition and broad substrate scope. [ABSTRACT FROM AUTHOR]

Direct structural modification of small‐molecule fluorophores represents a straightforward and appealing strategy for accessing new fluorescent dyes with desired functionalities. We report herein a general and efficient visible‐light‐mediated method for the direct C−H functionalization of BODIPY, an important fluorescent chromophore, using readily accessible and bench‐stable aryl and alkenylthianthrenium salts. This practical approach operates at room temperature with extraordinary site‐selectivity, providing a step‐economical means to construct various valuable aryl‐ and alkenyl‐substituted BODIPY dyes. Remarkably, this protocol encompasses a broad substrate scope and excellent functional‐group tolerance, and allows for the modular synthesis of sophisticated symmetrical and asymmetrical disubstituted BODIPYs by simply employing different combinations of thianthrenium salts. Moreover, the late‐stage BODIPY modification of complex drug molecules further highlights the potential of this novel methodology in the synthesis of fluorophore‐drug conjugates. [ABSTRACT FROM AUTHOR]

Light‐activated drug delivery systems allow precise spatiotemporal control of a drug release process. However, safe and efficient drug release activation needs a low‐power nonpulsed red/near‐infrared light with high tissue penetration depth. Nevertheless, such systems remain a challenge. Herein, a self‐assembled nanovehicle made of 2,6‐diiodo‐B‐dimethyl‐boron dipyrromethene (BODIPY)‐based photocleavable trigonal molecules bearing Pt(II) meso‐tetraphenyltetranaphthoporhyrin photosensitizer and a fluorescent release marker Nile Red in hydrophobic core is introduced. The system employs endothermic triplet–triplet energy transfer between the photosensitizer and the trigonal molecule, leading to the cleavage of the trigonal molecule followed by cargo release. This allows to engage 730 nm light to cleave BODIPY photoremovable protecting groups (PPGs) instead of 530 nm light that would be needed for direct photocage excitation. Therefore, the approach unleashes the desired activation of drug release via photocleavage with longer wavelengths (within the phototherapeutic window) without any chemical modification of the PPGs. Cell studies demonstrate fast intracellular uptake of the nanovehices by PC3 human prostate cancer cells with accumulation in lysosomes in 2 h. Light irradiation at 730 nm on nanovehicles dispersed in cell media leads to payload release. Remarkably, the system exhibits higher release efficiency at low oxygen concentration than at ambient thus allowing to tackle aggressive hypoxic solid tumors. [ABSTRACT FROM AUTHOR]

The human body synthesizes catecholamine neurotransmitters, such as dopamine and noradrenaline. Monitoring the levels of these molecules is crucial for the prevention of important diseases, such as Alzheimer's, schizophrenia, Parkinson's, Huntington's, attention-deficit hyperactivity disorder, and paragangliomas. Here, we have synthesized, characterized, and functionalized the BODIPY core with picolylamine (BDPy-pico) in order to create a sensor capable of detecting these biomarkers. The sensing properties of the BDPy-pico probe in solution were studied using fluorescence titrations and supported by DFT studies. Catecholamine sensing was also performed in the solid state by a simple strip test, using an optical fiber as the detector of emissions. In addition, the selectivity and recovery of the sensor were assessed, suggesting the possibility of using this receptor to detect dopamine and norepinephrine in human saliva. [ABSTRACT FROM AUTHOR]

In this study, diiodo boron dipyrromethene (BODIPY) is employed as the energy donor and 3,4,9,10-perylene tetracarboxylic dianhydride (PDA) as the energy acceptor, enabling the synthesis of two new compounds: a BODIPY-perylene dyad named Pl, and a triad named P2. To investigate the impact of the energy donor on the photophysical processes of the system, P1 comprises one diiodo-BODIPY unit and one PDA unit, whereas P2 contains two dhodo-BODIPY moieties and one PDA unit. Due to the good spectral complementarity between diiodo-BODIPY and PDA, these two compounds exhibit excellent light-harvesting capabilities in the 400–620 nm range. Steady-state fluorescence spectra demonstrate that when preferentially exciting the diiodo-BODIPY moiety, it can effectively transfer energy to PDA; when selectively exciting the PDA moiety, quenching of PDA fluorescence is observed in both P1 and P2. Nanosecond transient absorption results show that both compounds can efficiently generate triplet excited states, which are located on the PDA part. The lifetimes of the triplet states for these two compounds are 103 and 89 μs, respectively, significantly longer than that of diiodo-BODIPY. The results from the photooxidation experiments reveal that both P1 and P2 demonstrate good photostability and photooxidation capabilities, with P2 showing superior photooxidative efficiency. The photooxidation rate constant for P2 is 1.3 times that of P1, and its singlet oxygen quantum yield is 1.6 times that of P1. The results obtained here offer valuable insights for designing new photosensitizers. [ABSTRACT FROM AUTHOR]

Three new chromophores based on difluoroborondipyrromethene dyes (Bodipy‐1, Bodipy‐2, and Bodipy‐3) are used as precursors to prepare luminescent solar concentrators (LSC) based on poly‐acrylate, following a thermally activated polymerization involving lauryl methacrylate as monomer, ethyl glycol dimethacrylate as cross‐linking agent, and lauroyl peroxide as initiator. The new dyes exhibit typical BODIPY absorption and emission properties in dichloromethane fluid solution, assigned to the lower‐lying singlet π–π∗ level, which in the case of Bodipy‐2 and Bodipy‐3, both containing diamino‐substituted styryl subunits in their structure, has a strong charge transfer contribution. The LSCs obtained starting from each of the three Bodipys are interfaced to silicon photovoltaic (PV) cells, and the PV light‐to‐energy conversion efficiencies ηopt for the three systems are calculated. The results yield ηopt of 4.53% for LSC‐Bodipy‐1, 5.26% for LSC‐Bodipy‐2, and 8.23% for LSC‐Bodipy‐3. The optical efficiency for LSC‐Bodipy‐3 is a remarkable value among the LSC based on organic dyes. [ABSTRACT FROM AUTHOR]

Molecular sensors are a new and rapidly developing tool in biochemical research. They enable the exploration of biochemical reaction mechanisms and the prompt diagnosis of pathological conditions. Fluorescent dyes based on boron dipyrromethene (BODIPY) complexes are widely used as molecular sensors. This study demonstrates the potential for characterizing processes occurring in the blood plasma coagulation system across different age groups, including patients with acute myocardial infarction. In elderly individuals, compared to younger people, the blood clotting process begins earlier, the formation of fibrin slows down, and thrombin activity decreases. This technique can detect an increase in thrombin activity accompanied by a higher concentration of fibrinogen in patients with heart pathology. In such cases, blood clotting starts later and lasts longer. These changes in indicators can be attributed to the emergency administration of heparin. On the one hand, heparin prevents the enlargement of a blood clot; on the other, it reduces the activity of the prothrombinase complex, which is beneficial for patients with myocardial infarction. Further observation of blood clotting reveals alterations in fibrin structure, leading to a lengthened stabilization time. Thus, the results obtained in this study are consistent with the literature. The presented method is applicable both for physiological studies of the coagulation process and in clinical practice. Additionally, this method can be used for the kinetic evaluation of anticoagulants' effects on hemostasis factor activity. [ABSTRACT FROM AUTHOR]

Understanding the intersystem crossing (ISC) mechanism of organic compounds is essential for designing new triplet photosensitizers. Herein, we investigated the ISC mechanism of a heavy atom‐free Bodipy derivative with thiomethyl substitution (S−BDP). A long‐lived triplet state was observed with nanosecond transient absorption spectroscopy with lifetime of 7.5 ms in a polymer film and 178 μs intrinsic lifetime in fluid solution, much longer as compared with what was previously reported (apparent triplet lifetime=15.5 μs). Femtosecond transient absorption studies retrieved an ISC time constant of ∼3 ns. Time‐resolved electron paramagnetic resonance (TREPR) indicated a special triplet electron spin polarization phase (ESP) pattern (a, e, a, e, a, e) for S−BDP, different from the ESP (e, e, e, a, a, a) typical for the spin‐orbital coupling (SOC) mechanism. This indicates that the electron spin selectivity of the ISC of S−BDP is different from that of the normal SOC effect in iodo‐Bodipy. Simulations of the TREPR spectra give a zero‐field‐splitting D parameter of −2257 MHz, much smaller as compared to the reference 2,6‐diiodo‐Bodipy (D=−4380 MHz). The computed SOC matrix elements (0.28–1.59 cm−1) and energy gaps for the S1/Tn states suggest that the energy matching between the S1 and T2/T3 states (supported by the largest kISC ∼109 s−1) enhances the ISC for this compound. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) is one of the signaling molecules that are ubiquitous in humans, which involves in the regulation of human physiology and pathology. In this work, the probe PEC was designed and synthesized based on BODIPY fluorophore that can selectively detect CO through reducing the nitro group to amino group, resulting in a "turn-on" fluorescence response with a simultaneous increase in the concentration of CO. The response is selective over a variety of relevant reactive free radicals, ions, and amino acid species. PEC has the advantages of good stability, good water solubility, and obvious changes in fluorescence signals. In addition, PEC can be used to detect and track endogenous CO in living cells. [ABSTRACT FROM AUTHOR]

Abstract We report on the synthesis of two new threaded BODIPYs 5 and 6 in good yields using boron as a gathering atom and a macrocycle with a 2,2’‐biphenol unit. In addition to usual techniques, they were characterized by X‐ray crystallography. Their electrochemical and optical properties were investigated. In particular, both compounds are highly emissive with photoluminescence quantum yields of 54 and 81 % respectively. In addition, they both show a high photostability.

Icosahedral boron clusters-based BODIPY dyes represent a cutting-edge class of compounds that merge the unique properties of boron clusters with the exceptional fluorescence characteristics of BODIPY dyes. These kinds of molecules have garnered substantial interest due to their potential applications across various fields, mainly including optoelectronics, bioimaging, and potential use as boron carriers for Boron Neutron Capture Therapy (BNCT). Carborane clusters are known for their exceptional stability, rigid geometry, and 3D-aromaticity, while BODIPY dyes are renowned for their strong absorption, high fluorescence quantum yields, and photostability. The integration of carborane into BODIPY structures leverages the stability and versatility of carboranes while enhancing the photophysical properties of BODIPY-based fluorophores. This review explores the synthesis and structural diversity of boron clusters-based BODIPY dyes, highlighting how carborane incorporation can lead to significant changes in the electronic and optical properties of the dyes. We discuss the enhanced photophysical characteristics, such as red-shifted absorption and emission poperties, charge and electronic transfer effects, and improved cellular uptake, resulting from carborane substitution. The review also delves into the diverse applications of these compounds. In bioimaging, carborane-BODIPY dyes offer superior fluorescence properties and cellular internalization, making them ideal for cell tracking. In photodynamic therapy, (PDT) these dyes can act as potent photosensitizers capable of generating reactive oxygen species (ROS) for targeted cancer treatment making them excellent candidates for PDT. Additionally, their unique electronic properties make them suitable candidates for optoelectronic applications, including organic light-emitting diodes (OLEDs) and sensors. Overall, carborane-BODIPY dyes represent a versatile and promising class of materials with significant potential for innovation in scientific and technological applications. This review aims to provide a comprehensive overview of the current state of research on carborane-BODIPY dyes, highlighting their synthesis, properties, and broad application spectrum.

A series of seven new meso-phenyl BODIPY-pyrrolo[3,4-b]pyridin-5-one conjugates were synthesized in one experimental step by using a Sc(III)-catalyzed Ugi-Zhu three-component reaction coupled to a cascade sequence (aza Diels-Alder/N-acylation/aromatization) as post-MCR functionalization process. Further experimental studies were performed behind understanding the fluorescence response toward viscosity. All compounds exhibited a linear response between increasing viscosity (DMSO and glycerol mixtures) and fluorescence intensity. The different substituents also influenced the photophysical properties. Furthermore, in DMSO all compounds exhibited dual emission. Each band is attributed to the pyrrolo[3,4-b]pyridin-5-one and BODIPY moieties, respectively. The electronic structure of all compounds was computed by DFT and TD-DFT calculations, allowing to determine the molecular orbitals involved in the electronic transitions.

Lipid droplets (LDs) are organelles associated with lipid storage and energy metabolism, thus, their morphology and quantity are of significant research interest. While commercially available BODIPY dye effectively labels LDs in various cell types, it also labels lysosome-related organelles (LROs) in C. elegans, leading to non-specific LD quantification. Here, we report that the fluorescent signals of BODIPY exhibit distinct fluorescence lifetime patterns for LROs and LDs, which can be captured, visualized, and filtered by fluorescence lifetime imaging microscopy. Furthermore, we proposed and validated a method based on fluorescence lifetime that can improve the accuracy of fat storage quantification in BODIPY vital-staining worms, which holds broad applications, including rapid and accurate LD quantification in forward genetic screening. Additionally, our method enables observing dynamic LD-LRO interactions in living worms, a unique capability of BODIPY vital staining. Our findings highlight distinct BODIPY fluorescence lifetime characteristics of LDs and LROs, providing a valuable tool for future research on LDs, LROs, or their interactions.

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.

Meso‐nitrile oxide group in 1,7‐Diphenyl‐containing BODIPYs can be involved in highly unusual [3+2] intramolecular cycloaddition reaction with the formation of the dihydrobenzo[d]isoxazole‐containing BODIPYs. Oxidation of these compounds results in the formation of unprecedented either benzisoxazole‐ or benzo[b]azepine‐fused fully conjugated NIR absorbing BODIPYs. The photophysical properties and electronic structures of the target compounds were studied by an array of experimental and theoretical methods. [ABSTRACT FROM AUTHOR]