Broadly Tunable Atmospheric Water Harvesting in Multivariate Metal–Organic Frameworks

Abstract

Development of multivariate metal−organic frameworks (MOFs) as derivatives of the state-of-art water-harvesting material MOF-303 {[Al(OH)(PZDC)], where PZDC 2− is 1Hpyrazole-3,5-dicarboxylate} was shown to be a powerful tool to generate efficient water sorbents tailored to a given environmental condition. Herein, a new multivariate MOF-303-based waterharvesting framework series from readily available reactants is developed. The resulting MOFs exhibit a larger degree of tunability in the operational relative humidity range (16%), regeneration temperature (14 °C), and desorption enthalpy (5 kJ mol −1 ) than reported previously. Additionally, a high-yielding (≥90%) and scalable (∼3.5 kg) synthesis is demonstrated in water and with excellent space-time yields, without compromising framework crystallinity, porosity, and water-harvesting performance.

MOF Linker Extension Strategy for Enhanced Atmospheric Water Harvesting

“…In addition, we conducted water sorption analysis at different temperatures and utilized these data to assess the isosteric heat of water adsorption Q st using the Clausius–Clapeyron relation (Supporting Information, Section S9). We found that MOF-LA2-1 exhibits an average Q st value of 51 kJ mol –1 an overall reduction of 3 kJ mol –1 compared to its parent framework evaluated at similar conditions . Considering the heat of condensation of water (44 kJ mol –1 at 25 °C), this resembles a 30% lower heat of adsorption penalty compared to MOF-303.…”

“…We found that MOF-LA2-1 exhibits an average Q st value of 51 kJ mol −1 �an overall reduction of 3 kJ mol −1 compared to its parent framework evaluated at similar conditions. 23 Considering the heat of condensation of water (44 kJ mol −1 at 25 °C), this resembles a 30% lower heat of adsorption penalty compared to MOF-303. Importantly, we note that the favorable water sorption properties of MOF-LA2-1 were not compromised when using the green reflux-based synthesis for its preparation (Supporting Information, Section S9).…”

A hexagon based Mn(ii) rod metal–organic framework – structure, SF6gas sorption, magnetism and electrochemistry

“…Two steps in the water uptake were observed at p / p 0 between 0.1 and 0.3. The shape of the water sorption isotherms are comparable to some MOFs that have been investigated for water harvesting, 19 CTH-18 may thus be interesting for water harvesting applications, although this is beyond the scope of the present study.…”

Metal‐Organic Frameworks with Rod Yttrium Secondary Building Units

“…While the pore size of this MOF is approximately 1.1 nm as determined from crystallographic data, the 1D pore system within the channels lacks primary adsorption sites that have a strong affinity for carbon dioxide and water molecules [15] . Specifically, in terms of water sorption, compared to previously reported state‐of‐art water harvesting rod MOFs, [2a,8a,b,9b,16] MOF‐419 has hydroxamate groups (−CONHOH) and formate ligands (HCOO) in place of carboxylic groups (−COOH) and bridging hydroxy groups (−OH), respectively, which are considered binding sites for water molecules. As suggested by the crystal structure of MOF‐419 (Figure 1d), potential primary adsorption sites such as −NH and −COO are not easily accessible by those water molecules passing through the channel, as their geometry relation is unlike the one of hydrophilic atoms and hydroxyl groups in water harvesting MOFs such as MOF‐303.…”