Unravelling Water Stability and Electrical Conductivity of 2D Layered Metal-Organic Frameworks in Aqueous Solutions

TL;DR

This study uses molecular dynamics and electronic structure calculations to explore how water interacts with 2D layered metal-organic frameworks, revealing insights into their stability and conductivity in aqueous environments.

Contribution

It provides a detailed computational analysis of water adsorption and stability in 2D MOFs, highlighting the role of hydrogen bonding and van der Waals interactions in preserving their structure.

Findings

Water prefers hydrogen bonding to organic linkers over Cu2+ sites.

Cu3(HTTP)2 exhibits stronger van der Waals interactions, maintaining layered morphology.

Results inform strategies to preserve MOF integrity and conductivity in water.

Abstract

Molecular dynamics simulations combined with periodic electronic structure calculations are performed to decipher structural, thermodynamical and dynamical properties of the interfaced vs. confined water adsorbed in hexagonal 1D channels of the 2D layered electrically conductive Cu3(HHTP)2 and Cu3(HTTP)2 metal-organic frameworks (HHTP=2,3,6,7,10,11-hexahydroxytriphenylene and HTTP = 2,3,6,7,10,11-hexathiotriphenylene). Comparing water adsorption in bulk vs. slab models of the studied 2D MOFs shows that water is preferentially adsorbed on the framework walls via forming hydrogen bonds to the organic linkers rather than by coordinating to the coordinatively unsaturated open-Cu2+ sites. Theory predicts that in Cu3(HTTP)2 the van der Waals interactions are stronger which helps the MOF maintain its layered morphology with allowing very little water molecules to diffuse into the interlayer space. Data presented in this work are general and helpful in implementing new strategies for preserving the integrity as well as electrical conductivity of porous materials in aqueous solutions.