Gadolinium(III)‐Hydroxy Ladders Trapped in Succinate Frameworks with Optimized Magnetocaloric Effect

Two kinds of inorganic gadolinium(III)‐hydroxy “ladders”, [2× n ] and [3× n ], were successfully trapped in succinate (suc) coordination polymers, [Gd 2 (OH) 2 (suc) 2 (H 2 O)] n ⋅ 2 n  H 2 O ( 1 ) and [Gd 6 (OH) 8 (suc) 5 (H 2 O) 2 ] n ⋅ 4 n  H 2 O ( 2 ), respectively. Such coordination polymers could be regarded as alternating inorganic–organic hybrid materials with relatively high density. Magnetic and heat capacity studies reveal a large cryogenic magnetocaloric effect (MCE) in both compounds, namely (Δ H =70 kG) 42.8 J kg −1  K −1 for complex 1 and 48.0 J kg −1  K −1 for complex 2 . The effect of the high density is evident, which gives very large volumetric MCEs up to 120 and 144 mJ cm −3  K −1 for complexes 1 and 2 , respectively.