Heteroatom effects on the magnetic exchange interactions in bis(2,4,6-trichlorophenyl)methyl-based diradicals

Abstract

Stable luminescent diradicals have recently garnered significant research interest due to their promising application prospects. The intramolecular magnetic interactions in a series of bis(2,4,6-trichlorophenyl)methyl(BTM)-based diradicals coupled by a range of heteroatom-doped anthracene couplers have been studied via quantum chemistry calculations to highlight their spin-dependent luminescence properties. The doubly doped heteroatoms lead to spin crossover due to the heteroatom blocking effect, which was rationalized based on spin density distributions and spin alternation rules. This reduces spin delocalization from spin centres to the doped heteroatoms, conferring weaker magnetic exchange coupling and smaller ΔE_S–T values. Some potential candidates are proposed for magnetoluminescence and thermally activated emission. This work helps understand the effect of heteroatoms on regulating magnetic exchange coupling in BTM (TTM)-based diradicals, and it provides a reference for efficient luminescent diradicals.