The fluorescence of a pyrene-arylmaleimide dyad and its Diels-Alder adduct can be thermally modulated through reversible Diels-Alder reaction of arylmaleimide unit with furan. Moreover, the fluorescence intensities of the Diels-Alder adduct of dyad 1 with furan vary linearly with the temperatures of the corresponding solutions, demonstrating that these molecules are interesting compounds for Studies of fluorescent molecular thermometers. (c) 2005 Elsevier Ltd. All rights reserved.