Synthesis, solvatochromism and large two-photon absorption cross-sections of water-soluble dipicolinate-based pyridinium salts

Abstract Three D–π–A type pyridinium salts based on dipicolinate were synthesized. Compared to the corresponding neutral chromophores, enhanced two-photon absorption activity and water solubility were obtained. When measured by the Z -scan technique at 800 nm, the three molecules display considerably high values of two-photon absorption cross-section. The two-photon absorption cross-section values were found to be in the range 2421–25,318 GM. In addition, the three molecules exhibit pronounced negative solvatochromism and possess absorption spectral sensitivities to pH and to changes in the water content of tetrahydrofuran.