Tuning the Magnetic Properties of Diamagnetic Di-Blatter’s Zwitterion to Antiferro- and Ferromagnetic Diradical

Abstract

<div>In the quest of obtaining organic molecular magnets based on stable diradicals, we have tuned the inherent zwitterionic ground state of tetraphenylhexaazaanthracene (TPHA), the molecule embraced with two Blatter’s moieties, by adopting two different strategies. In the first strategy, we have increased the length of the coupler between the two radical moieties and observed a transition from zwitterionic ground state to diradicalized state. With larger coupler, remarkably strong ferromagnetic interactions are realized based on DFT and WFT based CASSCF/NEVPT2 methods. An analysis based on extent of spin contamination, CASSCF orbitals occupation numbers, HOMO-LUMO and SOMOs energy gap is demonstrated that marks the transition of ground state in these systems. In another approach, we systematically explore the effect of push-pull substitution on the way to obtain molecules based on TPHA skeleton with diradicaloid state and in some cases, even triplet ground state.</div>