Synthesis and photophysical properties of a novel pyridinium salt based on dipicolinate

A novel pyridinium salt based on dipicolinate, PM-1 was synthesized from the corresponding neutral chromophore and enhanced two-photon absorption activity was obtained. The two-photon absorption cross section value is 6.8 × 102 GM. PM-1 exhibits pronounced negative solvatochromism and possesses high absorption spectral sensitivities to pH and water content changes. PM-1 could be used as pH probe and to measure the water content, particularly for less than 10%, in common water miscible organic solvents such as THF, 1,4-dioxane, acetone and methanol.