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A Hoffman-like coordination polymer with appreciable porosity and uncoordinated pyridyl groups, namely, [Fe(2,5-bpp){Au(CN)2}2] ⋅ x Solv (2,5-bpp=2,5-bis(pyrid-4-yl)pyridine; Solv=solvent), was synthesised and characterised. A series of fascinating spin-crossover behaviours with abrupt, stepwise and hysteretic features were obtained by exchange with a range of protic solvents (ethanol, n-propanol, isopropyl alcohol, sec-butanol and isobutanol). Guest-host hydrogen-bonding interactions involving the H-accepting site of the framework are primarily responsible for the pronounced cooperativity of these spin-crossover behaviours. Meanwhile, the tunable critical temperatures over a range of about 130 K are presumably attributable to a certain degree of competition between internal pressure and local electronic influences of solvents. [ABSTRACT FROM AUTHOR]

The transformation of MnII glycolates (glc) between the three-dimensional coordination polymer [Mn(glc)2] n ( 1) and discrete mononuclear phase [Mn(glc)2(H2O)2] ( 2) can be reversibly switched by water molecules, which dramatically change the magnetocaloric effect (MCE) of MnII glycolates from the maximum of 6.9 J kg−1 K−1 in 1 to 60.3 J kg−1 K−1 in 2. This case example reveals that the effect of magnetic coupling on MCE plays a dominant role over that of other factors such as magnetic density for 3d-type magnetic refrigerants. [ABSTRACT FROM AUTHOR]

Two kinds of inorganic gadolinium(III)-hydroxy 'ladders', [2× n] and [3× n], were successfully trapped in succinate (suc) coordination polymers, [Gd2(OH)2(suc)2(H2O)] n ⋅ 2 n H2O ( 1) and [Gd6(OH)8(suc)5(H2O)2] n ⋅4 n H2O ( 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. [ABSTRACT FROM AUTHOR]