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A rhodamine-based chemosensor was synthesized and found to selectively bind ferric ions over other metal ions (Na+, K+, Ca2+, Mg2+, Fe2+, Zn2+, Cd2+, Co2+, Hg2+ Cr3+, Al3+) in an organic-aqueous mixture (CH3CN-MES). Upon addition of ferric ions, the spirolactam ring opens, producing a visual color change and a fluorescence intensity increase, i.e. a “turn on” optical response at 577 nm is observed. The chemosensor coordinates to ferric ions in 1:1 stoichiometry with a calculated Ka = 3.5 × 104 mol⋅dm−3 by fluorescence spectroscopy and a LoD of 27 ppb. The chemosensor was reversible upon addition of the Fe3+ chelator desferrioxamine. One- and two-dimensional NMR experiments with Al3+ ions aided in understanding of the coordination environment of the ferric ion with the chemosensor, which were confirmed by molecular modeling calculations. X-ray quality crystals of the chemosensor were obtained, and the solid-state structure is reported. Confocal microscopy was used to detect free ferric ions in Staphylococcus aureus.

Silicon complexes of corrole were obtained for the first time by reaction of the free-base corrole with hexachlorodisilane. The peripheral substituents of corrole strongly influence the nature of the reaction products: β-octaalkyl corrole was mainly isolated as the μ-oxo dimer, while a hydroxo complex was obtained in the case of 5,10,15-tris-(pentafluorophenyl)corrole. In the case of meso-tritolyl corrole, a mixture of monomer/μ-oxo dimer was obtained. The silicon corrole complexes are more stable toward hydrolysis than the corresponding porphyrin derivatives and are endowed with brilliant luminescence properties. The high affinity of silicon for fluoride ion allowed investigation of the ability of an Si corrole to serve as a sensor for F− detection. The strong color variation due to the interaction with the halide ion makes the Si corrole an interesting material for the naked-eye detection of inorganic fluoride.

Phosphorus complexes of corrole have recently attracted increasing interest since these compounds can be easily prepared in good yields, are stable, and show unusual optical properties. For these reasons, phosphorus corroles represent a class of interesting compounds to be exploited in the field of material science or for biomedical investigations and the definition of synthetic pathways for their functionalization is an important step to optimize their properties for various applications. We report here the reactivity of the phosphorus complex of 5,10,15-tritolylcorrole in the nitration or bromination reaction. Both these attempts were successful, allowing the preparation of substituted phosphorus corroles, which can be used as intermediates of more complex architectures endowed with useful properties. Furthermore, the crystallographic characterization of both complexes shows that they have an unusual ruffled geometry of the corrole core, a conformation that has not been considered possible for such a macrocycle.