A topology approach to overcome the pore size/volume trade-offs for autonomous indoor humidity control

Autonomous indoor humidity control is gaining more and more attention but is limited by the trade-offs among pore volume, pore size and water stability of water adsorbents. We solve this problem by using a unique coordination network topology combined with hydrolytically stable M(III) carboxylate clusters. By extending the ligand length from 9.0 to 11.2 and 13.7 Å, the pore volume significantly increases from 0.99 to 1.40 and 1.78 cm³ g⁻¹, which proportionally increases the saturated water adsorption capacity. Meanwhile, the pore size slightly increases from 10.4 to 11.0 and 13.5 Å, which restricts the isotherm inflection pressure and hysteresis width to meet the requirement of indoor humidity control. Large single-crystals suitable for X-ray diffraction studies were obtained by using Fe(III) salts, while isostructural frameworks with sufficiently high water stabilities were synthesized by using Cr(III) salts, which offer record working capacity of 0.90 and 1.10 g g⁻¹ for indoor humidity control.