Tuning the Structure and Electronic Properties of B–N Fused Dipyridylanthracene and Implications on the Self-Sensitized Reactivity with Singlet Oxygen

We demonstrate that the modification of anthracene with B ← N Lewis pairs at their periphery serves as a highly effective tool to modify the electronic structure with important ramifications on the generation and reactivity toward singlet oxygen. A series of BN-fused dipyridylanthracenes with Me groups in different positions of the pyridyl ring have been prepared via directed electrophilic borylation. The steric and electronic effects of the substituents on the structural features and electronic properties of the isomeric borane-functionalized products have been investigated in detail, aided by experimental tools and computational studies. We find that BDPA-2Me, with Me groups adjacent to the pyridyl N, has the longest B–N distance and shows overall less structural distortions, whereas BDPA-5Me with the Me group close to the anthracene backbone experiences severe distortions that are reflected in the buckling of the anthracene framework and dislocation of the boron atoms from the planes of the phenyl ring...