Unusual luminescent properties of odd- and even-substituted naphthyl-derivatized dioxetanes.
With the advent of enzymatically induced chemiluminescence and improved instrumentation for luminometry, ultrasensitive detection of a wide variety of analytes is now possible using standard immunoassay and DNA probe formats. Model molecular orbital calculations and literature precedent suggest that the singlet efficiencies observed upon decomposition of dioxetanes appended with donor substituted aromatic moieties are dependent on substitution pattern. We have recently discovered, in a series of 3-(2'-spiroadamantane)-4-methoxy-4-acetoxynaphth-2'-yl-1,2-+ ++dioxetanes, that enzymatic generation of a non-conjugated, charge transfer excited state results in luminescence of markedly different properties than that observed from an isomeric, conjugated excited state. An example of the former type, 3-(2'-spiroadamantane)-4-methoxy-4-(7"-acetoxy)naphth-2'-yl- 1,2- dioxetane (1) emitting at 550 nm, not only provides an increase in phi CL, but exhibits a dramatic bathochromic shift of 80-110 nm from the 460 nm emission of the conjugated isomer 3-(2'-spiroadamantane)-4-methoxy-4-(6"-acetoxy)naphth-2'-yl- 1,2-dioxetane (2). These developments, along with the attendant glow-type luminescence kinetics displayed during the enzymatic decomposition of the new 'odd-pattern' dioxetane, allow the design of simple protocols capable of simultaneous or 'multichannel' detection of several analytes.