In order to improve the fluorescence properties of the green fluorescent protein chromophore,
p‑HOBDI ((5‑(4‑hydroxybenzylidene)‑2,3‑dimethyl‑3,5‑dihydro‑4H‑imidazol‑4‑one), sixteen
dihydroimidazolone derivates were synthesized from thiohydantoin and arylaldehydes.
The synthesis developed is an efficient, novel, one-pot procedure. The study provides
a detailed description of the spectroscopic characteristics of the newly synthesized
compounds, using p‑HOBDI as a reference. The new compounds all exhibited significantly
stronger fluorescence than p‑HOBDI, up to 28 times higher quantum yields. An experimental
and theoretical investigation of the relationship of the fluorescence properties with
the molecular structure was also carried out. A good correlation was found between
the emission wavenumber and the Hammett constant of the functional group, which suggests
the intermolecular charge transfer (ICT) mechanism between the aromatic groups.
