Strategic Acetylation of BODIPY Dyes: Tuning Excited-State Geometry for the Design of Fluorogenic Sensing Probes

Strategic acetylation and alkylation modulate the photophysical properties of BODIPY dyes. <i>Meso</i>-acetylated <b>D8COMe</b> exhibits a large Stokes shift through excited-state geometric reorganization, while C2-acetylated <b>D2COMe</b> preserves characteristic BODIPY spectral features. Introduction of methyl groups at the C1/C7 positions influences fluorescence efficiency, with <b>T8COMe</b> showing viscosity-dependent emission. Computational analyses confirm structural distortion as the primary mechanism for fluorescence modulation. These structure-property relationships enable the rational design of fluorogenic probes for nucleophilic species detection and viscosity sensing applications.