Redox Activity of Electronically Excited Phosphorus Corroles with Axial Chalcogenation

Quest for visible-light absorbing metal-free corroles is of increased research interest for both electrocatalytic and photocatalytic applications among others. To this direction, phosphorus corrole (PC) and its functional derivatives hold great potential. In this study, the ground- and excited-state redox properties of PC and its several axially chalcogenated derivatives (XPC; XO, S, Se) are investigated using optimally tuned range-separated hybrid combined with polarizable continuum model for accounting of solvent effects. All XPCs are confirmed to be dynamically stable from normal-mode analysis and also found to possess similar Gibbs free energy changes for their synthesis from the parent freebase corrole. Calculated ground-state ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>S</mml:mi> <mml:mn>0</mml:mn></mml:msub> </mml:mrow> </mml:math> ) redox potentials indicate corrole-centered reduction and oxidation for all the studied molecules. While the nature of the chalcogen only marginally influences the lowest excited singlet ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>S</mml:mi> <mml:mn>1</mml:mn></mml:msub> </mml:mrow> </mml:math> ) and triplet ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>T</mml:mi> <mml:mn>1</mml:mn></mml:msub> </mml:mrow> </mml:math> ) states including the contributing frontier molecular orbitals, the excited-state photodynamics are greatly affected by the chalcogenation leading to chalcogen-dependent access to either <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>S</mml:mi> <mml:mn>1</mml:mn></mml:msub> </mml:mrow> </mml:math> / <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>T</mml:mi> <mml:mn>1</mml:mn></mml:msub> </mml:mrow> </mml:math> for redox processes. A qualitatively similar trend is observed in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>S</mml:mi> <mml:mn>0</mml:mn></mml:msub> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>S</mml:mi> <mml:mn>1</mml:mn></mml:msub> </mml:mrow> </mml:math> / <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow><mml:msub><mml:mi>T</mml:mi> <mml:mn>1</mml:mn></mml:msub> </mml:mrow> </mml:math> -state redox potentials, albeit of markedly different values. These findings contribute valuable insights for the development of next-generation energy-efficient electrocatalysts and photocatalysts utilizing metal-free, visible-light absorbing corrole macrocycles.