NEW MOLECULAR-SYSTEMS FOR FUNCTIONAL DYE-BASED MOLECULAR SWITCHING OFLUMINESCENCE

Three types of molecular switching processes involving luminescence ar e reported. The first section deals with photochemical induced switchi ng. The bisarylene-substituted dihydroazulene/vinylheptafulvene (DHA-P A/VHF-PA) couple containing a photoswitchable substructure (photochemi cal forward and thermal reverse reaction) shows on/off switching of lu minescence arising from the fluorescent DHA-PA and the non-fluorescent VHF-PA. The second part pertains to electrochemically induced switchi ng. Benzodifurane quinone BFQ-A can reversibly be reduced to the hydro quinone dianion BFQ-A(2-) in a two-step process via quinone radical an ion BFQ-A(.-) BFQ-A and BFQ-A(.-) are non-fluorescent or weakly fluore scent respectively, whereas reduction to BFQ-A(2-) leads to a signific ant fluorescence. In the third part the generation of electrochemilumi nescence (ECL) by the stilbene-like compounds SN-A ON-A and OS-A is de scribed. Electrochemical and optical properties were investigated by c yclic voltammetry and spectroelectrochemical methods.