Investigation of the factors influencing the selectivity and response times of glyoxal-selective probes

Abstract

In this work, four o-phenylenediamine-conjugated fluorescent probes 1–4 with different substituents on the amino group have been designed and prepared to investigate the factors influencing the selectivity and response times of the probes toward glyoxal (GO). The introduced substituted groups, including n-propyl, iso-propyl, tert-butyl, and phenyl, 1–4 displayed sufficient selectivity toward GO. Due to the fact that GO normally exists in a hydrated state in aqueous media, the reaction rates between 1–4 and GO exhibited significant deviation from the steric hindrance effects of most organic reactions. Compounds 3 and 4 with bulky substituted groups presented faster reaction rates with GO than those of compounds 1–2. To further elucidate the properties of these compounds, we selected compound 3 as the representative compound, because of its best selectivity and fast response time, for detailed investigation of the recognition behaviors both in aqueous solution and in living cells. Probe 3 exhibited high selectivity and high sensitivity toward GO with a large Stokes shift (>100 nm), making it highly suitable for in vivo imaging research.