A novel blue luminescent material Na2[Co(C2O4)2(H2O)2]•6H2O: synthesis, structure, luminescence and magnetic properties

The synthesis, crystal structure and physical properties of new disodium trans-diaquabis(oxalato) cobaltate(II)-hexahydrate {Na-2[Co(C2O4)(2)(H2O)(2)]center dot 6H(2)O} crystals have been investigated. Single crystal X-ray analysis reveals that this compound crystallizes in the triclinic system with the space group P (1) over bar. The structure of this complex consists of [Co(C2O4)(2)(H2O)(2)](2-) anionic units with a slightly distorted octahedral geometry of cobalt surrounded by four oxygen atoms of two oxalate groups. The anionic units are interlinked by two Na+ ions with different octahedral and distorted octahedral environments. The electronic absorption spectra of the compound exhibit bands at 208, 246 and 526 nm in the UV and visible regions. A strong blue luminescence was observed at room temperature when excited at 355 nm. The M(H) curve at 2 K shows a significant nonlinear behaviour with almost zero coercivity which clearly indicates an extremely weak antiferromagnetic/ferromagnetic state of the complex.