The influence of tetrahydroquinoline rings in dicyanomethylenedihydrofuran (DCDHF) single-molecule fluorophores

We have synthesized several series of DCDHF fluorophores with the amine donor either acyclic or constrained in one or two tetrahydroquinoline rings. The absorption and the fluorescence emission wavelengths and quantum yields have been determined and correlated with the specific donor structures. Generally, inclusion of the donor in a ring annulated to the benzene or naphthalene aromatic (Ar) π-core results in a bathochromic shift of absorption and emission accompanied by an increase in the quantum yield. Thus, the tetrahydroquinoline donor provides an efficient way to tailor the properties of fluorophores with substituted amines as electron-donating groups.