Abstract:A new class of organic nanoparticles(CN-MBEnanoparticles)withameandiameterofca.3040nm,whichexhibitastronglyenhancedfluorescenceemission,werepreparedbyasimplereprecipitation method.CN-MBE(1-cyano-trans-1,2-bis-(4′-methylbiphenyl)ethylene)isveryweaklyfluorescentinsolution, buttheintensityisincreasedbyalmost700timesinthenanoparticles.EnhancedemissioninCN-MBE nanoparticlesisattributedtothesynergeticeffectofintramolecularplanarizationandJ-typeaggregate formation(restrictedexcimerformation)innanopaticles.On/offfluorescenceswitchingfororganicvapor wasdemonstratedwithCN-MBEnanoparticles