Engineering Heteronuclear Arrays from Ir^(Ⅲ)-Metalloligand and Co^(Ⅱ)Showing Coexistence of Slow Magnetization Relaxation and Photoluminescence

Three heteronuclear Ir^(Ⅲ)-Co^(Ⅱ)arrays,[Co(H_(2)O)6]_(2)[Ir(ppyCOO)(ppyCOOH)(bpy)]_(2)[Ir(ppyCOO)_(2)(bpy)]_(2)(NO_(3))2·10.5H_(2)O(2),[Co(H_(2)O)6]{Co-(H_(2)O)4[Ir(ppyCOO)_(2)(bpy)]_(2)}[Ir(ppyCOO)_(2)(bpy)]2·15H_(2)O(3)and{Co(H_(2)O)2[Ir(ppyCOO)_(2)(bpy)]_(2)}·2CH_(3)OH·3H_(2)O(4),have been synthe-sized by combining paramagnetic Co^(Ⅱ)ion with luminescent Ir^(Ⅲ)-metalloligand,[Ir(ppyCOOH)_(2)(bpy)][Ir(ppyCOO)_(2)(bpy)]·5H_(2)O(1),where ppyCOOH=3-(pyridin-2-yl)benzoic acid and bpy=2,2'-bipyridyl.Owing to the variable charged states of compound 1 at dif-ferent pH,compounds 2 and 3 are discrete ionic complexes containing hydrated Co^(2+)cations and deprotonated[Ir(ppyCOO)_(2)(bpy)]-anions as well as coexisting neutral[Ir(ppyCOO)(ppyCOOH)(bpy)](for 2)or Co(H_(2)O)_(4)[Ir(ppyCOO)_(2)(bpy)]_(2) trinuclear molecule(for 3).Whereas compound 4 consists of self-assembled two-dimensional coordination polymer with Co-metalloligand dative bonds.The hexa-coordinated Co^(Ⅱ)cores in all complexes display octahedral geometries with varying degrees of distortion.In a bias dc field,the ac susceptibilities for 2-4 reveal slow magnetic relaxation.Moreover,the solid-state phosphorescence is observed for compounds 2 and 3 due to weak supramolecular interaction between Co^(Ⅱ)ion and Ir-moiety but is severely quenched for 4,where the Co center is strongly connected to the metalloligand.To the best of our knowledge,this is the first report of Ir-Co systems showing both slow magnetization relaxation and photoluminescence.