Two 3D Mn-based coordination polymers: synthesis, structure and magnetocaloric effect.

Two three-dimensional (3D) coordination polymers, namely Mn II 6 (CH 3 COO) 2 (HCOO) 2 (IN) 8 (C 4 H 8 O) 2 (H 2 O) and Mn III 6 Mn II 12 (μ 3 -O) 6 (CH 3 COO) 12 (IN) 18 (H 2 O) 7.5 (abbreviated as Mn II 6 and Mn II 12 Mn III 6 respectively; HIN = isonicotinic acid), were synthesized by the reaction of Mn(CH 3 COO) 2 ·4H 2 O and isonicotinic acid under solvothermal conditions. Magnetic studies revealed that antiferromagnetic interactions may be present in compounds Mn II 6 and Mn II 12 Mn III 6 . Moreover, the values of -Δ S m (26.27 ( Mn II 6 ) and 37.69 ( Mn II 12 Mn III 6 ) J kg -1 K -1 at Δ H = 7 T) are relatively larger than those of the reported Mn-based coordination polymers. This work provides a great scope in the magnetocaloric effect (MCE) of pure 3d-type systems.