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Abstract A sterically strained 32π‐electron antiaromatic bis‐BODIPY macrocycle in which two BODIPY fragments are linked byp‐divinylbenzene groups was prepared and characterized. Unlike regular BODIPYs, the fluorescence in this macrocycle is quenched. The broad signals in the NMR spectra of the macrocycle were explained by the vibronic freedom of thep‐divinylbenzene fragments. The possible diradicaloid nature of the macrocycle was excluded on the basis of variable‐temperature EPR spectra in solution and in solid state, which is indicative of its closed‐shell quinoidal structure. Themeso‐C−H bond in the macrocycle and its precursor BODIPY dialdehyde3forms a weak hydrogen bond with THF and is susceptible for the nucleophilic attack by organic amines and cyanide anion. The reaction products of such a nucleophilic attack havemeso‐sp3carbon atoms and were characterized by NMR, mass spectrometry and, in one case, X‐ray crystallography. Unlike the initial bis‐BODIPY macrocycle, the adducts have strong fluorescence in the 400 nm region. The electronic structure and spectroscopic properties of new chromophores were probed by density functional theory (DFT) and time‐dependent DFT (TDDFT) calculations and correlate well with the experimental data.
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This content will become publicly available on August 25, 2026
A thioether‐linked iodinated BODIPY‐benzimidazole photosensitizer: Efficient light‐induced production of singlet oxygen and superoxide radicals and photobiological activity
Abstract A new iodinated BODIPY dye incorporating a thioether‐ has been synthesized and characterized. The benzimidazole unit was introduced at themeso‐pentafluorophenyl position of the BODIPY scaffold via high‐yield click chemistry. This substitution does not alter the strong absorption and emission properties of the BODIPY chromophore and provides a versatile platform for the attachment of pharmacologically important molecules. Further functionalization of the BODIPY core with iodine at the 3‐ and 5‐positions yields a derivative capable of generating reactive oxygen species when irradiated with low energy light. Experimental evidence confirms the production of both singlet oxygen and superoxide radicals, indicating this complex is capable of operating by both Type I and Type II photosensitization pathways. This dual capacity could be responsible for its effectiveness as a photosensitizer and contribute to its photobiological activity against human melanoma cells.
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- Award ID(s):
- 2400127
- PAR ID:
- 10649732
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Photochemistry and Photobiology
- ISSN:
- 0031-8655
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Photoinduced electron transfer (PET) in newly assembled dyads formedviametal‐ligand axial coordination of phenylimidazole‐functionalized bis(styryl)BODIPY (BODIPY(Im)2) and zinc tetrapyrroles, that is, zinc tetratolylporphyrin (ZnP), zinc tetra‐t‐butyl phthalocyanine (ZnPc) and zinc tetra‐t‐butyl naphthalocyanine (ZnNc), in non‐coordinatingo‐dichlorobenzene (DCB) is investigated using both steady‐state and time‐resolved transient absorption techniques. The structure of the BODIPY(Im)2was identified by using single crystal X‐ray structural analysis. The newly formed supramolecular dyads were fully characterized by spectroscopic, computational and electrochemical methods. The binding constants measured from optical absorption spectral studies were in the range of ∼104 M−1for the first zinc tetrapyrrole binding and suggested that the two imidazole entities of bis(styryl)BODIPY behave independently in the binding process. The energy level diagram established using spectral and electrochemical studies suggested PET to be thermodynamically unfavorable in the ZnP‐bearing complex while for ZnPc‐ and ZnNc‐bearing complexes such a process is possible when zinc tetrapyrrole is selectively excited. Consequently, occurrence of efficient PET in the latter two dyads was possible to establish from femtosecond transient absorption studies wherein the electron transfer products, that is, the radical cation of zinc tetrapyrrole and the radical anion of BODIPY(Im)2, was possible to spectrally identify. From target analysis of the transient data, time constants of circa 3 ns for ZnPc⋅+:BODIPY⋅−and circa 0.5 ns for ZnNc⋅+:BODIPY⋅−were obtained indicating persistence of the radical ion‐pair to some extent. The electron acceptor property of bis(styryl)BODIPY in donor‐acceptor conjugates is borne out from the present study.more » « less
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