摘要
The decay pathways with relative quantum efficiencies for photoexcited trans-aminostilbenes in dilute organic solutions at ambient temperature are reviewed. Like the case of the parent trans-stilbene, fluorescence and the vinylene C=C torsion are two important decay pathways for trans-aminostilbenes. However, a new pathway, that is, formation of a TICT state by twisting the phenylene-amino C-N bond, dominates the excited-state deactivation of some trans-aminostilbenes in medium and/or highly polar solvents. On the basis of the quantum yields of fluorescence (Φ f ) and the trans → cis isomerization (Φ tc ) in solvents of different polarity, the TICT-forming activity of trans-aminostilbenes could be readily probed. The TICT states could be unambiguously characterized with ring-bridged model compounds, profiles of the emission spectra, and variable-temperature emission spectra. The interplay among fluorescence, the trans → cis isomerization, and the TICT state formation strongly depend on the nature and position of the amino group(s), the solvent polarity, and the other substituents that significantly perturb the steric and/or electronic properties. This provides a unique opportunity toward the design of novel fluorescent probes, light-emitting materials, and molecular switches.