Energy Transfer‐Mediated Magnetoluminescence of an Octahedral Mn II Complex Ligated With Bis(Diphenylphosphino)Methane Dioxide

Magnetic‐field effect on luminescence (MagLum) has attracted considerable attention owing to fundamental understanding of spin‐luminescence correlations as well as its potential application to functional magneto‐optical devices. Recent studies have revealed that open‐shell luminescent molecular systems, including organic radicals and lanthanide complexes, exhibit MagLum. However, the underlying mechanisms in such molecular systems are largely restricted to those based on simple Zeeman splitting of spin sublevels. Here, we report pronounced MagLum behaviors of an octahedral Mn II complex ligated with bis(diphenylphosphino)methane dioxide ([ Mn II L 3 ](BF 4 ) 2 ) doped into the corresponding Zn II complex ([ Zn II L 3 ](BF 4 ) 2 ) solids at various concentrations (1, 5, 10, 30 wt%). We demonstrate that the magnetic‐field modulation of the energy‐transfer efficiency from the Zn II complex to the Mn II complex is a key process governing the MagLum behaviors. This mechanism is distinctly different from those for organic radicals and lanthanide complexes, establishing a novel strategy for realizing MagLum. Our findings extend the scope of magnetic field‐responsive luminescence materials to paramagnetic transition metal complexes, thereby opening new avenues for the design and application of paramagnetic luminescent compounds in future photo‐ and spin‐based technologies.