Effect of the o-Acetamido Group on pH-Dependent Light Emission of a 3-Hydroxyphenyl-Substituted Dioxetane Luminophore

A pioneering chemiluminescent molecule reported by Schaap and co-workers, 3-(2′-spiroadamantane)-4-methoxy-4-(3″-hydroxy)phenyl-1,2-dioxetane (AMPD), does not require enzymatic activation but is unsuitable for use under physiological conditions. To overcome this limitation, we have developed a new AMPD derivative that contains an acetamido group at the ortho position of the hydroxy group as an intramolecular hydrogen-bonding site in order to lower the pKa value. This compound exhibits a superior chemiluminescence response to AMPD in the physiologically relevant pH range.