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

Abstract

The synthesis, crystal structure and physical properties of new disodium trans-diaquabis(oxalato)cobaltate(II)hexahydrate {Na₂[Co(C₂O₄)₂(H₂O)₂]·6H₂O} crystals have been investigated. Single crystal X-ray analysis reveals that this compound crystallizes in the triclinic system with the space group P. 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.