Modulation of the Photophysical Properties of β-substituted BODIPY Dyes

Tautomeric equilibrium, proton affinity and mass spectrometry fragmentation of flexible hydrogen-bonded precursors and rigid [Formula: see text] fluorescent dyes

The stability of two groups of conformationally locked molecules, similar in topology, but differing only by the type of the bridge rigidifying their structure, is studied. The series of the less-rigid 2-phenacylheterocyclic compounds and their stiff difluoroboranyl derivatives are investigated for the determination of the effect of [Formula: see text]/S/O replacement in a five-membered heterocyclic ring and the presence of a strong electron-donating group on the tautomeric equilibrium, protonation affinity, and fragmentation pattern observed in the structural elucidation by means of mass spectrometry technique. The results of the [Formula: see text]B97X-D/6-311++G(d,p) calculations, the topological analysis of electron density as well as the experimental MS measurements show the importance of the number of heteroatoms, their properties, and location in the molecule for the rational design of the systems of desired stable tautomers or the favorable protonation sites. The obtained data allow for the understanding of the fundamentals of the novel highly fluorescent difluoroborates fragmentation behavior, vital for their structural elucidation with the application of high-resolution tandem mass spectrometry methods.

Design, synthesis and biological activity of bis-sulfonyl-BODIPY probes for tumor cell imaging

In recent years, BODIPY derivatives have become one of the research hotspots in the field of bioprobes, but most of them have the problems of poor hydrophilicity, low biocompatibility and no targeting. In this paper, novel ethylenediamine bridging bis-sulfonyl-BODIPY fluorescent probes were successfully designed and synthesized to solve these problems; What's more, the cytotoxicity analysis, cell imaging, in vivo imaging and apoptosis experiments were carried out. Ethylenediamine bridges and oxygen-rich sulfonyl groups made such probes had certain hydrophilicity, so they could be dissolved in dimethylsulfoxide and methanol. The IC₅₀ value of compound 9 in HCT-116 cells was 93.12 ± 6.33 µM, and in HeLa cells was 89.09 ± 11.84 µM, which indicating that the probe had certain inhibitory effect on cancer cells. The excellent biocompatibility and potential tumor targeting properties of the compound were clearly observed in cell and mice imaging. This study is of great significance for the rational design of novel targeted BODIPY probes with good hydrophilicity and biocompatibility.

Stimuli Responsive Confinement of a Molecular Rotor Based BODIPY Dye inside a Cucurbit[7]uril Nanocavity

Present study reports the interaction of a molecular rotor based BODIPY dye, 8-anilino-BODIPY (ABP), with a versatile macrocyclic molecule, cucurbit[7]uril (CB7), investigated through various techniques such as ground-state absorption, steady-state fluorescence, time-resolve emission, proton NMR, and quantum chemical studies. Although BODIPY dyes have widespread applications due to their intriguing photochemical properties, studies on their noncovalent interactions with different macrocyclic hosts, especially regarding their supramolecularly induced modulations in photophysical properties are very limited. The investigated BODIPY dye, especially its protonated ABPH⁺ form (pH ∼ 1), shows a large fluorescence enhancement on its interaction with the CB7 host, due to large reduction in the structural flexibility for the bound dye, causing a suppression in its nonradiative de-excitation process in the excited state. Unlike ABPH⁺, the neutral ABP form (pH ∼ 7) shows considerably weaker interaction with CB7. For ABPH⁺-CB7 system, observed photophysical results indicate formation of both 1:1 and 1:2 dye-to-host complexes. Plausible geometries of these complexes are obtained from quantum chemical studies which are substantiated nicely from ¹H NMR results. The response of the ABPH⁺-CB7 system toward changing temperature of the solution have also been investigated elaborately to understand the potential of the system in different stimuli-responsive sensor applications.