Preparation of dipyrrins from F-BODIPYs by treatment with methanesulfonic acids

An alternative metal-free soft procedure for the preparation of dipyrrins from F-BODIPYs is reported. The new method makes possible to obtain certain dipyrrin derivatives that were unaccessible from F-BODIPYs to date. To demonstrate the ability of the new procedure, dipyrrins having highly reactive groups, such as chloro, cyano or acetoxyl, have been easily obtained from the corresponding F-BODIPY, which shows the synthetic utility of the reported methodology

Formylation as a Chemical Tool to Modulate the Performance of Photosensitizers Based on Boron Dipyrromethene Dimers

Heavy-atom-free photosensitizers are envisioned as the next generation of photoactive molecules for photo-theragnosis. In this approach, and after suitable irradiation, a single molecular scaffold is able to visualize and kill tumour cells by fluorescence signalling and photodynamic therapy (PDT), respectively, with minimal side effects. In this regard, BODIPY-based orthogonal dimers have irrupted as suitable candidates for this aim. Herein, we analyse the photophysical properties of a set of formyl-functionalized BODIPY dimers to ascertain their suitability as fluorescent photosensitizers. The conducted computationally aided spectroscopic study determined that the fluorescence/singlet oxygen generation dual performance of these valuable BODIPY dimers not only depends on the BODIPY-BODIPY linkage and the steric hindrance around it, but also can be modulated by proper formyl functionalization at specific chromophoric positions. Thus, we propose regioselective formylation as an effective tool to modulate such a delicate photonic balance in BODIPY-based dimeric photosensitizers. The taming of the excited-state dynamics, in particular intramolecular charge transfer as the key underlying process mediating fluorescence deactivation vs. intersystem crossing increasing, could serve to increase fluorescence for brighter bioimaging, enhance the generation of singlet oxygen for killing activity, or balance both for photo-theragnosis.This research received financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN)/Agencia Estatal de Investigación (AEI) Grants: PID2020-114755GB-C32 and -C33 funded by MCIN/AEI/10.13039/501100011033. Gobierno Vasco (IT1639-22) is also grateful for the financial support

Circularly Polarized Luminescence from Simple Organic Molecules

This article aims to show the identity of “circularly polarized luminescent active simple organic molecules” as a new concept in organic chemistry due to the potential interest of these molecules, as availed by the exponentially growing number of research articles related to them. In particular, it describes and highlights the interest and difficulty in developing chiral simple (small and non-aggregated) organic molecules able to emit left- or right-circularly polarized light efficiently, the efforts realized up to now to reach this challenging objective, and the most significant milestones achieved to date. General guidelines for the preparation of these interesting molecules are also presented

Functionalization of photosensitized silica nanoparticles for advanced photodynamic therapy of cancer

BODIPY dyes have recently attracted attention as potential photosensitizers. In this work, commercial and novel photosensitizers (PSs) based on BODIPY chromophores (haloBODIPYs and orthogonal dimers strategically designed with intense bands in the blue, green or red region of the visible spectra and high singlet oxygen production) were covalently linked to mesoporous silica nanoparticles (MSNs) further functionalized with PEG and folic acid (FA). MSNs approximately 50 nm in size with different functional groups were synthesized to allow multiple alternatives of PS-PEG-FA decoration of their external surface. Different combinations varying the type of PS (commercial Rose Bengal, Thionine and Chlorine e6 or custom-made BODIPY-based), the linkage design, and the length of PEG are detailed. All the nanosystems were physicochemically characterized (morphology, diameter, size distribution and PS loaded amount) and photophysically studied (absorption capacity, fluorescence efficiency, and singlet oxygen production) in suspension. For the most promising PS-PEG-FA silica nanoplatforms, the biocompatibility in dark conditions and the phototoxicity under suitable irradiation wavelengths (blue, green, or red) at regulated light doses (10–15 J/cm2) were compared with PSs free in solution in HeLa cells in vitro

Red haloBODIPYs as theragnostic agents: The role of the substitution at meso position

Three different molecular designs based on BODIPY dye have been proposed as photosensitizers (PSs) for photodynamic therapy (PDT) by the inclusion of halogen atoms (Iodine) at 2,6-positions and with extended conjugation at 3, 5-positions and varying the substitution at meso position. The synthesis is described and their main photophysical features including singlet oxygen production and triplet states were characterized by absorption and fluorescence spectroscopy (steady-state and time-correlated) and nanosecond transient absorption spectroscopy. The results were compared with the commercial Chlorin e6. The three new red-halogen-BODIPYs showed a great balance between singlet oxygen generation (ΦΔ≥0.40) and fluorescence (Φfl≥0.22) for potential application on PDT, and particularly in theragnosis. In vitro experiments in HeLa cells were done to study their performance and to elucidate the best potential candidate for PDT

Development of Geometry-Controlled All-Orthogonal BODIPY Trimers for Photodynamic Therapy and Phototheragnosis

We have established an easy synthetic protocol for selectively developing all-orthogonal BODIPY trimers with unprecedented geometries on the basis of selecting methyl oxidation versus electrophilic formylation of key dimeric precursors. Photophysical characterization together with biological assays unraveled the most suitable BODIPY−BODIPY geometrical arrangements within the trimer, forcing them to serve as molecular platforms for the development of new, advanced heavy-atom-free photosensitizers for photodynamic therapy and phototheragnosis