Two iridium complexes,namely[Ir(ppy)_(2)(mbpymbh)]PF_(6)(1)and[Ir(dfppy)_(2)(mbpymbh)]PF_(6)(2),exhibit unexpected photoreactivity,although the incorporated ligands ppyH,dfppyH and mbpymbh have no inherent photochemic...Two iridium complexes,namely[Ir(ppy)_(2)(mbpymbh)]PF_(6)(1)and[Ir(dfppy)_(2)(mbpymbh)]PF_(6)(2),exhibit unexpected photoreactivity,although the incorporated ligands ppyH,dfppyH and mbpymbh have no inherent photochemical activity.The molecular aggregates of 1 and 2,formed in a CH_(3)CN-H_(2)O(v/v=1/9)mixed solvent,show photo-induced luminescence switching,with the emission-color change from red to orange for 1,while a transition from the off state to on state with an emission band at 566 nm for 2.These changes in luminescence are assigned to photo-induced oxidative cyclization of the acylhydrazone units in 1 and 2,thus generating photoproducts 1-O and 2-O.Complexes 1-O and 2-O were isolated and identified from their crystal structures.We discussed both the effect factors and the reaction mechanism of the photo-oxidation reactions for complexes 1 and 2,as well as the luminescence properties of complexes 1,2,1-O and 2-O.The discovery of photo-induced oxidative cyclization in this work not only provides a new class of photo-responsive luminescent materials,but also offers a novel synthesis method for 1,3,4-oxadiazole-based Ir(Ⅲ)complexes.展开更多
文摘Two iridium complexes,namely[Ir(ppy)_(2)(mbpymbh)]PF_(6)(1)and[Ir(dfppy)_(2)(mbpymbh)]PF_(6)(2),exhibit unexpected photoreactivity,although the incorporated ligands ppyH,dfppyH and mbpymbh have no inherent photochemical activity.The molecular aggregates of 1 and 2,formed in a CH_(3)CN-H_(2)O(v/v=1/9)mixed solvent,show photo-induced luminescence switching,with the emission-color change from red to orange for 1,while a transition from the off state to on state with an emission band at 566 nm for 2.These changes in luminescence are assigned to photo-induced oxidative cyclization of the acylhydrazone units in 1 and 2,thus generating photoproducts 1-O and 2-O.Complexes 1-O and 2-O were isolated and identified from their crystal structures.We discussed both the effect factors and the reaction mechanism of the photo-oxidation reactions for complexes 1 and 2,as well as the luminescence properties of complexes 1,2,1-O and 2-O.The discovery of photo-induced oxidative cyclization in this work not only provides a new class of photo-responsive luminescent materials,but also offers a novel synthesis method for 1,3,4-oxadiazole-based Ir(Ⅲ)complexes.
