Cyclometalated Iridium(Ⅲ) Complexes:Synthesis,Crystal Structure And Third-order Nonlinear Optical Properties

Metal organic compounds,also known as organometallic compounds,are characterized by the presence of a metal carbon bond（M-C bond）,which are directly formed from the bonding of metal atoms and carbon atoms.Among many metal-organic compounds,the cyclometalated iridium（Ⅲ）complexes have attracted much attention due to the excellent luminescence properties and potential application value in many fields,such as OLEDs,LECs,cell imaging and chemical sensing.In recent years,more and more attention has been paid to the application of cyclometalated iridium（Ⅲ）complexes in the field of nonlinear optics.It is well known that the structures and optical properties of cyclometalated iridium（Ⅲ）complexes can be adjusted by the designing and synthesizing of chelating ligand（C^N）and auxiliary ligand（N^N）,and then investigate the relationship between the properties and the coordination geometry of cyclometalated iridium（Ⅲ）complexes.In this article,several new types of cyclometalated iridium（Ⅲ）complexes with asymmetric structures have been designed and synthesized by modifying the structures and functional groups of auxiliary ligands（N^N）.The third-order nonlinear optical properties of these complexes have been studied and the relationship between structures and properties were also explored.Firstly,the iridium dimer[Ir（ppz）₂（μ-Cl）]₂was synthesized.Subsequently,the cationic cyclometallated iridium（Ⅲ）complexes were prepared by using iridium dimer[Ir（ppz）₂（μ-Cl）]₂as chelating precursors and incorporating the diverse auxiliary ligands.The crystals of cyclometalated iridium（Ⅲ）complexes were obtained by solvent diffusion or hydrothermal reaction method.The structures and properties of these complexes have also been well-characterized.（1）The aminoquinoline auxiliary ligands were produced by aniline,4-nitroaniline andquinoline-2-formaldehyde under condensation reaction.Two cationic complexs of C1and C2 were formed by the reaction of iridium dimer[Ir（ppz）₂（μ-Cl）]₂andiminoquinoline auxiliary ligands,with PF₆^?as counter ions.[Ir（ppz）₂（phqm）][（PF₆）]（C1）[Ir（ppz）₂（phqm-NO₂）][（PF₆）]（C2）（2）Pyridine-formaldehyde was used as the main raw material to synthesize the Schiff baseauxiliary ligands.The main feature of these auxiliary ligands is that two identical N^Ngroups are joined by a benzene ring or naphthalene to form a highly conjugated Schiffbase auxiliary ligands.The Schiff base auxiliary ligands have four nitrogen sites suitablefor coordination with the transition metal iridium.The binuclear cationic cyclometalatediridium（Ⅲ）complexs C3?C5 were synthesized from the iridium dimer[Ir（ppz）₂（μ-Cl）]₂and the Schiff auxiliary ligands,with PF₆^?as the counter ion.[Ir₂（ppz）₄（Phen BQu Me）][（PF₆）₂]（C3）[Ir₂（ppz）₄（Naph BPy Me）][（PF₆）₂]（C4）[Ir₂（ppz）₄（Phen BPy Me）][（PF₆）₂]（C5）（3）The nonlinear absorption performance of Bipyridine cyclometalated iridium（Ⅲ）complexes can be adjusted by changing the types of substituents in the auxiliary ligands（N^N）.Because they can easily affect the energy gaps of the highest occupied molecularorbitals（HOMO）and the lowest unoccupied molecular orbitals（LUMO）.In this paper,two pyridine cyclometalated iridium（Ⅲ）complexs C6?C7 were synthesized.[Ir（ppz）₂（Bi Phen Dica）]（C6）[Ir（ppz）₂（Bi Qu Lin）][（PF₆）]（C7）...