Anti-Stokes Fluorescence and Nonlinear Optical Properties of the Functionalized Phenoxazine-based Dye:A computational study

摘要

Tuning of electronic, photophysical and nonlinear optical(NLO)properties of the phenoxazin-3-one dye, resazurin(Rz), is here attempted through functionalization by employing the electron-donating and electron-withdrawing groups. Density functional theory(DFT)and time-dependent DFT calculations were performed for the purpose. Examining the absorption-emission spectra, featuring an intense band(ππ*)followed by a weak band(nπ*), of the functionalized dye derivatives reveal the Stokes shift, and relatively a large shift is found for the cyanofunctionalized Rz molecules. Surprisingly, the 2-mono-cyanoresazurin shows the anti-Stokes fluorescence(ASF)emission induced by the hot-band absorption, and at the other end, the weak absorption band associated to the charge transfer nπ* transition of the nitro-functionalized molecules is being quenched. Radiative lifetime analysis infers that the pull-type functionalized molecules decay slowly whereas the push-type shows the high emission rate. The structure-property relations between the molecular parameters were also discussed. Tuning the NLO properties infers that the pull-type group exhibits significantly high hyperpolarizabilities(for cyano-)whereas the push-type exhibits relatively small β-value(for amino-)when compared the standard NLO molecule. Here, the tetra-functionalized-Rz molecules may act as promising candidates for NLO applications, and also probing their ASF emission further unfolds the bio-applications.