The development of new fluorescent molecules is an active area of research due to their broad applicability and contributions to various scientific disciplines. Boron-dipyrromethene dyes (BODIPYs) stand out as a class of chromophores that offer highly tunable optoelectronic properties. However, much less is known about BODIPY analogues with heavier main-group elements as the central atom.

Alessandro Bismuto, University of Göttingen and University of Bonn, both Germany, and colleagues have reported the synthesis and characterization of antimony- and bismuth-based dipyrromethene complexes, celled SBDIPY and BIDIPY. The team added a tetrahydrofuran (THF) solution of different dipyrrin ligands and lithium bis(trimethylsilyl)amide (LiHMDS) to a THF solution of SbF₃, SbCl₃, or SbBr₃, to obtain SBDIPY complexes (example pictured above on the top left). The product obtained from SbF₃ has a dimeric structure (pictured above in the bottom row). According to the researchers, this is the first direct analogue of BODIPY containing fluoride handles. To obtain BIDIPYs, the team reacted BiCl₃ and sodium dipyrrinato salts in THF.

The researchers investigated the luminescence features of the complexes and found that replacing the boron in BODIPY with a heavier central atom has only minimal influence on the main electronic transition. The compounds have similar luminescence properties, however with notably lower stability, especially for bismuth.

• Replacing the BO in BODIPY: unlocking the path to SBDIPY and BIDIPY chromophores,
  André Korzun, Stefano Crespi, Christopher Golz, Alessandro Bismuto,
  Chem. Sci. 2023.
  https://doi.org/10.1039/d3sc01493b