查看文章

Understanding the molecular origins of the optoelectronic properties of fluorophores provides rational guidelines for chemists to synthesize better-performing dyes. Factors affecting the UV–vis absorption spectral shift, molar extinction coefficients, and Stokes shift of fluorophores are herein examined at the molecular level, via both (time-dependent) density functional theory-based calculations and the empirical harmonic-oscillator-stabilization-energy (HOSE) and bond-length-alternation (BLA) models. The importance of these factors is discussed using six coumarin dyes as exemplars. In particular, a special focus is devoted to the Stokes shift, a critical parameter in fluorophores. It is demonstrated that incorporating a “rotational” substituent in a fluorophore molecule with tailored steric hindrance effects and resonance effects leads to a substantial increase in the Stokes shift, not only in coumarins but also in other …