The generation of bio‐targetable photosensitizers is of utmost importance to the emerging field of photodynamic therapy and antimicrobial (photo‐)therapy. A synthetic strategy is presented in which chelating dipyrrin moieties are used to enhance the known photoactivity of iridium(III) metal complexes. Formed complexes can thus be functionalized in a facile manner with a range of targeting groups at their chemically active reaction sites. Dipyrrins with N‐ and O‐substituents afforded (dipy)iridium(III) complexes via complexation with the respective Cp*‐iridium(III) and ppy‐iridium(III) precursors (dipy=dipyrrinato, Cp*=pentamethyl‐η5‐cyclopentadienyl, ppy=2‐phenylpyridyl). Similarly, electron‐deficient [IrIII(dipy)(ppy)2] complexes could be used for post‐functionalization, forming alkenyl, alkynyl and glyco‐appended iridium(III) complexes. The phototoxic activity of these complexes has been assessed in cellular and bacterial assays with and without light; the [IrIII(Cl)(Cp*)(dipy)] complexes and the glyco‐substituted iridium(III) complexes showing particular promise as photomedicine candidates. Representative crystal structures of the complexes are also presented.

A series of BODIPYs were evaluated for their phototoxic activity against Gram-positive S. aureus and Gram-negative P. aeruginosa. Specifically, carbohydrate/dibromosubstituted BODIPYs showed a highly effective inactivation of S. aureus.

Boron–dipyrrins (BODIPYs) have found widespread application in bioimaging and materials science. These applications require the tuning of the chemical and photophysical properties of the fluorophore through the introduction of functional groups at the BODIPY core. In this context, an approach to difunctionalized BODIPYs was explored. Oxidative nucleophilic substitution of hydrogen (ONSH) in the 3‐(α‐)position of the BODIPYs was combined with nucleophilic substitution (SNAr) at the aryl unit of pentafluorophenyl‐substituted BODIPYs and their dipyrrane precursors. In an alternative approach, α‐alkoxy‐substituted BODIPYs were prepared starting from the corresponding dipyrrin. In this case, the α‐methoxy group of the BODIPY was susceptible to a hitherto unreported methoxy/amino exchange. The compounds were investigated with respect to their optical spectroscopic properties, revealing the influence of the different substitution patterns on their absorption and emission spectra.

The introduction of functional groups into the meso‐position of dipyrromethanes, boron‐dipyrromethenes (BODIPYs) and porphyrinoids, is of fundamental importance in designing such dye systems for material sciences or photomedicine. One route that has proven to be particularly useful in this respect is the nucleophilic aromatic substitution (SNAr) on porphyrinoids and their precursors carrying electron‐withdrawing substituents. To further expand this methodology, the potential of the 4‐fluoro‐3‐nitrophenyl and the 3,4,5‐trifluorophenyl moieties for the synthesis of functionalized dipyrromethanes, BODIPYs, and porphyrinoids has been evaluated. The 3,4,5‐trifluorophenyl moiety proved not to be applicable in the SNAr with nucleophiles. The introduction of the 4‐fluoro‐3‐nitrophenyl group, however, allowed fast and efficient SNAr with various amine nucleophiles. The synthesized 4‐amino‐3‐nitrophenyl‐substituted dipyrromethanes were successfully applied in the synthesis BODIPYs and were tested in the synthesis of “trans”‐A2B2 porphyrins and A2B corroles. Furthermore, the dipyrromethanes – after oxidation to the dipyrromethenes – were found to be suitable ligands for metal ions giving access to functionalized ruthenium(II) metal complexes.

The introduction of heavy atoms into the BODIPY-core structure has proven to be a straightforward strategy for optimizing the design of such dyes towards an enhanced generation of singlet oxygen...

Coordination complexes of iridium(III) are potential candidates for photodynamic therapy. Phenylpyridyl‐ and Cp*‐containing (dipyrrinato)iridium(III) complexes with a multitude of functional groups at the dipyrrin moieties were synthesized and the phototoxic activity of the complexes evaluated in tumor and bacterial cell assays. The Cp*‐containing and glycosylated dipyrrinato‐phenylpyridyl complexes are promising photoactive agents, as visualized in the cover design by Ella Marushchenko. More information can be found in the Full Paper by M. O. Senge, A. Wiehe, et al. on page 6440.

The Cover Feature shows an illustration of the wide range of pyrrole‐based dye molecules accessible via functionalized dipyrromethanes. Employing 5‐(4‐fluoro‐3‐nitrophenyl)dipyrromethane as the precursor, a highly efficient aromatic nucleophilic substitution with various amines is reported, leading to (4‐amino‐3‐nitrophenyl)‐functionalized dipyrromethanes. These dipyrromethanes can be converted into porphyrinoids, BODIPYs, and (dipyrrinato)ruthenium(II) complexes. Now, the 'quest' for using these compounds as possible photosensitizers for photodynamic therapy can begin. More information can be found in the Full Paper by A. Wiehe et al.