Fluorescence and chemiluminescence properties of indolylmaleimides: experimental and theoretical studies.

Various indolylmaleimides (IMs) were synthesized, and their fluorescence (FL) and chemiluminescence (CL) were measured. The substitution at the 2-position of the indole ring and the 3- or 4-position of the maleimide moiety caused an obvious change in the FL and CL of the IMs. An almost on-off switching of the FL of the IMs was observed.