A new method has been developed to detect the formation of carbon-carbon bonds by Diels-Alder reactions based on the fluorescence quenching of conjugated polymers. Conjugated copolymers containing various amounts of functional furan pendant groups (PFP-F) have been synthesized and characterized. A maleimide group lined to 1-methyl-4,4-bipyridinium iodide acts as the electron quencher (M-MV2+). The Diels-Alder reaction between the maleimide and furan moieties results in intra-molecular electron transfer from the conjugated copolymer to the MV2+, and thus the fluorescence of the conjugated copolymer is quenched via a photoinduced electron transfer process. Higher furan concentrations increase the fluorescence quenching efficiency (EF) of the conjugated copolymers. The copolymer PFP-F-3 with the highest furan content can be used as a platform to monitor Diels-Alder reactions. The PFP-F3/M-MV2+ system can also be sued to screen catalysts for Diels-Alder reactions.