Abstract: A new class of chemiluminescent acridinium or benzacridinium compounds is disclosed by virtue of forming an intramolecular energy transfer conjugate (ETC) between the acridinium or benzacridinium compound and a luminophore. A method of extending the emission wavelengths of acridinium or benzacridinium esters in order to further reduce or eliminate the emission spectral overlap between the parent polysubstituted aryl Acridinium Esters (DMAE) and Benzacridinium Esters (LEAE) is disclosed. The ETC's retain the unique desired properties of acridinium or benzacridinium compounds including complete light emission in very short period of time, monophasic emission spectrum, simplicity of triggering mechanism, ability of labeling the biological molecules of interest to form a tracer, and good stability. Additionally, the range of the emission spectrum of an acridinium or benzacridinium compound can now be shifted at will and at longer leap through the choice of a luminophore as the integral part of an ETC molecule.