Synthesis, Characterization, and Singlet Oxygen Sensitization by Antimony (III/V) Corrole Complexes

Abstract

AbstractThe synthesis, structural, spectroscopic characterization, and DFT/TD‐DFT calculations of antimony corroles are reported herein. The studied complexes can be described as [(Corr)SbIII] and [(Corr)(oxo)SbV]2, where Corr is the trianion of corrole. All these complexes are diamagnetic in nature as is evident from sharp peaks with normal chemical shifts in the 1H NMR spectra. Single crystal XRD analysis reveals that the antimony(V) corrole complex is the bis‐μ‐oxo‐bridged dinuclear antimony(V). Both the tetra and hexa‐coordinated [(Corr)SbIII] and [(Corr)(oxo)SbV]2 antimony complexes adopt domed‐structure with weak d‐π electron coupling. The Sb−O bond distances in the co‐facial dimer of [(Corr)(oxo)SbV]2 are 1.9802(16) Å (DFT: 2.0141 Å) (for Sb1−O1), and 1.9639(17) Å (DFT: 1.9957 Å) (for Sb2−O2) respectively. We observed that even though iodosobenzene is frequently used to oxidize [(Corr)SbIII] species, the oxidation of [(Corr)SbIII] is indeed very facile in nature and it even occurred in the air‐equilibrated CHCl3 solution while storing for few days. Excitation of these antimony (III/V) corrole complexes in DCM/MeOH (1 : 1) at 77 K results in red emission with maxima at 640–720 nm. The singlet oxygen production of [(Corr)(oxo)SbV]2 has a quantum yield of 69 % and is two times higher than the analogous [(Corr)SbIII] derivatives.