Synthesis and characterization of bent fluorine-containing donor-π-acceptor molecules as intense luminophores with large Stokes shifts

Herein, we prepared novel bent fluorine-containing donor-π-acceptor (D-π-A) molecules from commercially available octafluorocyclopentene using a facile two-step procedure, revealing that the above molecules absorb UV-light and exhibit yellow photoluminescence (PL) with high PL efficiencies ( Φ PL ) in solution. The corresponding Stokes shifts exceeded 10 000 cm −1 , and the maximum PL wavelength ( λ PL ) strongly depended on solvent polarity or intermolecular interactions in the solid state. On the basis of a Lippert-Mataga plot, PL was confidently assigned to radiative relaxation from an intramolecular charge-transfer excited state. Moreover, the synthesized luminophores showed intense PL even in the crystalline state and exhibited alkoxy chain length-dependent PL behavior ( e.g. , high Φ PL , λ PL = 486-540 nm). Bent fluorine-containing D-π-A molecules showed intense photoluminescence with large Stokes shifts stem from their twisted and bent molecular geometries.