Engineering Heteronuclear Arrays from Ir III ‐Metalloligand and Co II Showing Coexistence of Slow Magnetization Relaxation and Photoluminescence

• Published in: Chinese journal of chemistry 2022-04, Vol.40 (8), p.931-938
• Main Authors: Fan, Kun, Bao, Song‐Song, Yu, Zi‐Wen, Huang, Xin‐Da, Liu, Yu‐Jie, Kurmoo, Mohamedally, Zheng, Li‐Min
• Format: Article
• Language: English
• ISSN: 1001-604X; 1614-7065
• DOI: 10.1002/cjoc.202100783

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 synthesized 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 different 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.