Used as a key intermediate in the synthesis of triarylmethane dyes and photochromic compounds. It serves in the formulation of leuco dyes for thermal paper, where it acts as a color former that develops visible images upon heating in the presence of acidic developers. Also employed in the production of specialty indicators and sensors due to its strong color response to pH changes. Its electron-donating properties make it suitable for optoelectronic applications and nonlinear optical materials.