Slow relaxation and magnetic coupling of magnetization in 3D CoII2-xZnIIx chain-based coordination frameworks with mixed double azide-tetrazolate bridges

Abstract Five novel isomorphous 3D Co II 2-x Zn II x (0 ≤x ≤ 2) coordination frameworks formulated as [Co II 2-x Zn II x (pymtz) 2 (N 3 ) 2 (H 2 O) 2 ]·2H 2 O, (x = 0 ( 1 ), 1 ( 2 ), 1.5 ( 3 ), 1.7 ( 4 ), 2 ( 5 ), pymtz = 5-(3-pyrimidyl)tetrazolate) were synthesized by in situ hydrothermal reaction and then structurally and magnetically characterized. In these compounds, adjacent metal ions are linked by mixed double azide and tetrazolate bridges to give 1D coordination chains, and each chain is interlinked by pymtz ligands into 3D frameworks with (3,4,6)-connected net of (3.6.8)(3 2 .6 1 .7 3 )(3 2 .6 2 .8 8 .10 1 .11 2 ) topology. Magnetic studies indicate that the homometallic Co II compound ( 1 ) exhibits the coexistence of antiferromagnetic ordering and slow magnetic dynamics, while the bimetallic Co II 2-x Zn II x series ( 2 - 4 ) show the innocent blending effect which tends to decrease the blocking temperature ( T B ) of the spin slow dynamics. The homometallic Zn II compound ( 5 ) exhibits strong luminescence in the solid state at room temperature while the luminescent intensity of 5 gradually decreases as Zn II is replaced by Co II .