Aromatic-bridged and meso-meso-linked BF2-smaragdyrin dimers exhibit fast decays in polar solvents by symmetry-breaking charge transfer

Symmetry-breaking charge transfer is one of the key process in photosynthetic reaction centers and specific artificial optoelectronic devices such as dye-sensitized solar cells. Here we report the synthesis of aromatic-bridged BF₂-smaragdyrin dimers, meso-free BF₂-smaragdyrin, and its meso-meso-linked BF₂-smaragdyrin dimer. The decays of S₁-states of these dimers are accelerated with an increase in solvent polarity and a decrease in the distance between the two BF₂-smaragdyrin units, suggesting symmetry-breaking charge transfer. The fluorescence lifetimes of the dimers become shortened in polar solvents. However, ultrafast transient absorption spectroscopy do not detect charge-separated ion pairs. On the basis of these results, we conclude that the decays of the excited states of the BF₂-smaragdyrin dimers are accelerated by solvation-induced symmetry-breaking charge transfer, depending on the degree of the electronic interaction between the smaragdryin units as a rare case for porphyrinoids. The degree of charge transfer is larger for dimers with larger electronic interactions.

Synthesis and characterization of pyrrolyldipyrrin F-BODIPYs

A series of synthetic analogs of the tripyrrolic natural product prodigiosin were complexed with boron trifluoride to generate the corresponding F-BODIPYs.

Efficient two-step synthesis of water soluble BODIPY–TREN chemosensors for copper(ii) ions

Two promising, highly selective, water soluble, Cu(ii) sensors were synthesized in two reaction steps, using C–H functionalization reactions.

Robust synthesis of F-BODIPYs

A protocol is established for the high-yielding synthesis of F-BODIPYs involving non-anhydrous reagents and not requiring precautions to exclude moisture. This simple and robust strategy simply requires a second addition of NEt₃ and BF₃·OEt₂, midway through the reaction period. The ratio and amounts of NEt₃ and BF₃·OEt₂ used in each aliquot are critical to success (6 : 9 for each aliquot). The protocol can be completed using bench-dry apparatus, without need to achieve and maintain anhydrous conditions or solvents.