Blue-shift of photoluminescence induced by coupling effect of a nanohybrid composed of fluorophore–phenothiazine derivative and gold nanoparticles

A flurophore–phenothiazine derivative {2-[(10-ethyl-10H-phenothiazin-3-yl)-methylene] malononitrile, abbreviated as L} is designed, synthesized, and characterized by single crystal X-ray diffraction analysis. Further, L is used to couple with Au NPs to construct L–Au nanohybrid. Upon the coupling effect between L and Au components, blue-shifted photoluminescence with an obvious increased FL lifetime has been achieved. Surface enhanced Raman scattering analysis reveals that L molecules couple with Au NPs through S atoms. The coupling “hot spot” and the energy match between the Femi level of Au NPs and the frontier molecular orbital energy of L are effective factors in distributing the photogenerated electrons at the interface to tune the optical property. A D-π-A type phenothiazine derivative (L) was synthesized and used to prepare nanohybrid with Au NPs. L molecules coupled with Au NPs through S atoms, which brought about significant blue-shift of the fluorescence and an obvious increase of FL lifetime.