Rationally Designed Solvatochromic Fluorescent Indoline Derivatives for Probing Mitochondrial Environment.

A new class of solvatochromic, robust, and multifunctional fluorescent probes derived from indoline is presented. Specificity of mitochondria targeting was achieved and utilized for probing polarity under normal and apoptotic conditions. A large Stokes shift, high quantum yield, thermal, photochemical, and pH stability, tolerance to buffer compositions, and a bioconjugation tool-kit make it a promising candidate for live-cell fluorescence imaging.