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-pi-acceptor (D-pi-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 (phi(PL)) in solution. The corresponding Stokes shifts exceeded 10 000 cm(-1), and the maximum PL wavelength (lambda(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 phi(PL), lambda(PL) = 486-540 nm).