Fluorescence Resonance Energy Transfer of Monomer via Photoisomerization

We experimentally report a new photoisomerization mechanism of fluorescence resonance energy transfer (FRET) of monomer via photoisomerization. Firstly, a new photoisomerization was firstly report by us, in which trans, trans-1,4-Diphenyl-1,3-butadiene (tt-DPB) is photoisomerized to D-DPB (D stands for rotating double bond) by rotating double bond, evidenced by the three dimensional (3D) and 2D excitation-emission mappings, and firmly supported by theoretical calculations on potential energy surfaces. Secondly, absorption energy of the photoisomerized D-DPB is resonated with the fluorescence energy of tt-DPB. By the electronic state excitation of tt-DPB, the fluorescence of D-DPB is observed, which provide evidence of the FRET of DPB via photoisomerization. Our results provide a new mechanism on FRET of monomer via photoisomerization.