Strong multiphoton absorption properties of one styrylpyridinium salt in a highly polar solvent

Multiphoton absorption (MPA) effects have become useful for real applications as well as conceptual predictions. However, most of organic molecules exhibit small Stokes shift and reduced MPA in the highly polar solvents, which may seriously hinder their related applications. In this work, one styrylpyridinium salt has been synthesized, which exhibits outstanding properties such as bright red fluorescence at the wavelength of 626 nm in a highly polar solvent (DMSO). Importantly, it is noted that the material also exhibits strong two- and three-photon absorption action cross-section (δ_2PA = 597 GM and δ_3PA = 18 × 10^-80 cm⁶∙s²∙photon^-2, respectively), which can be excited in near-infrared (NIR) window I (650-900 nm) and NIR window II (1000-1450 nm). Meanwhile, two-photon in vitro bioimaging and MPA induced optical limiting behavior have been successfully demonstrated based on the chromophore.