Light-controlled switching of the spin state of iron(III).

ABSTRACT: Controlled switching of the spin state of transition metal ions, particularly of Fe^II and Fe^III, is a prerequisite to achieve selectivity, efficiency, and catalysis in a number of metalloenzymes. Here we report on an iron(III) porphyrin with a photochromic axial ligand which, upon irradiation with two different wavelengths reversibly switches its spin state between low-spin (S = ¹/₂) and high-spin (S = ⁵/₂) in solution (DMSO-acetone, 2:598). The switching efficiency is 76% at room temperature. The system is neither oxygen nor water sensitive, and no fatigue was observed after more than 1000 switching cycles. Concomitant with the spin-flip is a change in redox potential by ~60 mV. Besides serving as a simple model for the first step of the cytochrome P450 catalytic cycle, the spin switch can be used to switch the spin-lattice relaxation time T₁ of the water protons by a factor of 15.

SUBMITTER: Shankar S 

PROVIDER: S-EPMC6232099 | biostudies-literature |

REPOSITORIES: biostudies-literature