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.

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.

From photosensitizers to light harvesters adapting the molecular structure in all-BODIPY assemblies.

Herein we detail a protocol to design dyads and triads based solely on BODIPY dyes as halogen-free singlet oxygen photosensitizers or energy transfer molecular cassettes. The conducted photonic characterization reveals the key role of the BODIPY-BODIPY linkage to finely modulate the balance between the triplet state population and fluorescence decay.

BINOLated aminostyryl BODIPYs: a workable organic molecular platform for NIR circularly polarized luminescence.

The accessible at-boron-BINOLated 3,5-bis(4-aminostyryl)ated BODIPY scaffold is highlighted as a workable platform for developing enantiopure small organic molecules exhibiting CPL in the NIR region, even in water solution, the latter being key for CPL-based bioapplications. Synthetic simplicity, noticeable chiroptical efficiency in the NIR and the possibility to access water-soluble emitters pave the way for advancing CPL tools based on organic emitters and NIR radiation.