Synthesis and molecular structure of perhalogenated rhenium-oxo corroles.

ABSTRACT: As part of our efforts to develop rhenium-oxo corroles as photosensitizers for oxygen sensing and photodynamic therapy, we investigated the potential ?-perhalogenation of five ReO meso-tris(para-X-phenyl)corroles, Re[TpXPC](O) (X?=?CF3, H, F, CH3, and OCH3), with elemental chlorine and bromine. With Cl2, ?-octachlorinated products Re[Cl8TpXPC](O) were rapidly obtained for X?=?CF3, H, and CH3, but X?=?OCH3 resulted in overchlorination on the meso-aryl groups. Full ?-octabromination proved slower relative to Cu and Ir corroles, but the desired Re[Br8TpXPC](O) products were finally obtained for X?=?H and F after a week at room temperature. For X?=?CH3 and OCH3, these conditions led to undecabrominated products Re[Br11TpXPC](O). Compared to the ?-unsubstituted starting materials, the ?-octahalogenated products were found to exhibit sharp 1H NMR signals at room temperature, indicating that the aryl groups are locked in place by the ?-halogens, and substantially redshifted Soret and Q bands. Single-crystal X-ray structures of Re[Cl8TpCF3PC](O), Re[Cl8TpCH3PC](O), and Re[Br8TpFPC](O) revealed mild saddling for one Cl8 structure and the Br8 structure. These structural variations, however, appear too insignificant to explain the slowness of the ?-octabromination protocols, which seems best attributed to the deactivating influence of the high-valent Re center.

SUBMITTER: Alemayehu AB 

PROVIDER: S-EPMC7665048 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature