Grafting of hydrophilic ethylene glycols or ethylenediamine on coordinatively unsaturated metal sites in MIL-100(Cr) for improved water adsorption characteristics

Grafting of activated MIL-100(Cr) with EG (ethylene glycol), DEG (diethylene glycol), TEG (triethylene glycol) and EN (ethylenediamine) leads to a decrease of the BET surface area and pore volume. Yet, water adsorption isotherms of the modified compounds MIL-100(Cr)-EG, MIL-100(Cr)-DEG and MIL-100(Cr)-EN show a favored uptake of water at lower partial pressures and no loss of total water uptake capacity compared to non-modified MIL-100(Cr). The reduction in surface area is offset by an increased hydrophilicity and an advantageous smaller pore size for the adsorption of water. MIL-100(Cr) is therefore very promising as a water sorption material, e.g., for heat-transformation applications.