Synthesis and molecular structure of perhalogenated rhenium-oxo corroles

• Published in: Scientific reports Vol. 10; no. 1; p. 19727
• Main Authors: Alemayehu, Abraham B., Einrem, Rune F., McCormick-McPherson, Laura J., Settineri, Nicholas S., Ghosh, Abhik
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.11.2020; Nature Publishing Group; Springer
• Subjects: 639/638; 639/638/263; 639/638/403; 639/638/440; 639/638/549; 639/638/911; Bromine; chemical synthesis; Chemistry; Chemistry: 440; Chlorine; coordination chemistry; Halogens; Humanities and Social Sciences; inorganic chemistry; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Kjemi: 440; Laboratories; Ligands; Matematikk og Naturvitenskap: 400; Mathematics and natural science: 400; Molecular structure; multidisciplinary; organic chemistry; Photodynamic therapy; physical chemistry; Rhenium; Science; Science (multidisciplinary); VDP
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-020-76308-7

As part of our efforts to develop rhenium-oxo corroles as photosensitizers for oxygen sensing and photodynamic therapy, we investigated the potential β -perhalogenation of five ReO meso -tris( para -X-phenyl)corroles, Re[T p XPC](O) (X = CF 3 , H, F, CH 3 , and OCH 3 ), with elemental chlorine and bromine. With Cl 2 , β -octachlorinated products Re[Cl 8 T p XPC](O) were rapidly obtained for X = CF 3 , H, and CH 3 , but X = OCH 3 resulted in overchlorination on the meso -aryl groups. Full β -octabromination proved slower relative to Cu and Ir corroles, but the desired Re[Br 8 T p XPC](O) products were finally obtained for X = H and F after a week at room temperature. For X = CH 3 and OCH 3 , these conditions led to undecabrominated products Re[Br 11 T p XPC](O). Compared to the β -unsubstituted starting materials, the β -octahalogenated products were found to exhibit sharp 1 H NMR signals at room temperature, indicating that the aryl groups are locked in place by the β -halogens, and substantially redshifted Soret and Q bands. Single-crystal X-ray structures of Re[Cl 8 T p CF 3 PC](O), Re[Cl 8 T p CH 3 PC](O), and Re[Br 8 T p FPC](O) revealed mild saddling for one Cl 8 structure and the Br 8 structure. These structural variations, however, appear too insignificant to explain the slowness of the β -octabromination protocols, which seems best attributed to the deactivating influence of the high-valent Re center.