A chemically triggerable dioxetane of the Formula: ##STR10## wherein one of Z1 and Z2 is hydrogen and the other is an electron active substituent that does not suppress the chemiluminescent behavior of the dioxetane,one of A1 and A2 is hydrogen and the other is OX, wherein X is H or (E)3 Si, wherein each E is C1-12 alkyl or C6-12 aryl, wherein Y1 and Y2 are independently hydrogen, hydroxy, Cl, F,