Water Structure and Dynamics in Homochiral [Zn(l-L)(X)] Metal-Organic Frameworks

摘要

The structural, thermodynamic, and dynamical properties of water adsorbed in two homochiral metal-organic frameworks (MOFs) with general formula [Zn(l-L) (X)], X = Cl and Br, and L = 3-methyl-2-(pyridin-4-ylmethylamino)butanoic acid, are investigated through molecular dynamics simulations. Water molecules establish distinct hydrogen-bonding patterns within the pores of the two MOFs, which directly correlate with the strength of the underlying framework-water interactions. In particular, at low loading, the Zn-Cl groups of [Zn(l-L)(Cl)] effectively provide a templating scaffold for the formation of one-dimensional hydrogen-bonded water chains that propagate along the MOF channels following the helicity of the framework. In contrast, the relatively weaker framework-water interactions in [Zn(l-L) (Br)] lead to less ordered water distributions inside the pores. The simulation results are in agreement with the available experimental data and provide molecular-level insights into specific hydrogen-bonding motifs and spatial arrangements of the water molecules inside the pores, which can be related to the different proton conductivities measured for the two MOFs.