Control of the CT interaction between electron-donor and -acceptor moieties of a 1,4-dicyanonaphthalene–arene dyad for intermolecular exciplex or excimer formation in crystals

Colorless crystals of 1,4-dicyano-2-(4′-methoxybenzyloxy)methylnaphthalene (2), which is a 1,4-dicyano-2-methylnaphthalene (DCMN)–4-methylanisole (MA) dyad linked by an ether unit, selectively form a fluorescent intermolecular DCMN–MA exciplex (greenish blue, λ f exciplex = 456 nm ). In contrast, 1,4-dicyano-2-(4′-methylbenzyloxy)methylnaphthalene (3), which is a DCMN–p-xylene dyad, forms a fluorescent intermolecular DCMN–DCMN excimer in the crystalline state (blue, λ f excimer = 404 nm ). These findings demonstrate that a moderate charge transfer interaction takes place between the DCMN moiety of 2 and MA moieties of the adjacent molecules of 2, which successfully facilitates the preparation of light-emissive organic crystals.