An S‐shaped gas isotherm pattern displays high working capacity in pressure‐swing adsorption cycle, as established for CO2, CH4, acetylene, and CO. However, to our knowledge, this type of adsorption behavior has not been revealed for NH3 gas. Herein, we design and characterize a hydrogen‐bonded organic framework (HOF) that can adsorb NH3 uniquely in an S‐shape (type IV) fashion. While conventional porous materials, mostly with type I NH3 adsorption behavior, require relatively high regeneration temperature, this platform which has significant working capacity is easily regenerated and recyclable at room temperature.

Control of indoor CO2 concentration to a safe level is important to human health. Metal–organic-framework-based adsorbents show superior adsorption performance at moderate CO2 concentration compared to other solid adsorbents but suffer from low capacities and high regeneration temperature at indoor CO2 concentrations and poor humidity stability. Herein, we report epn-grafted Mg2(dobpdc) (epn = 1-ethylpropane-1,3-diamine) showing a CO2 capacity of 12.2 wt % at an acceptable concentration of 1000 ppm and a practically low desorption temperature of 70 °C, which surpasses the performance of conventional solid adsorbents under the given conditions. After poly­(dimethylsiloxane) coating, this material reveals a significant adsorption amount (∼10 wt %) in humid conditions (up to 98% relative humidity) with structural durability.

Heavily tetraethylenepentamine (tepa)-functionalized Mg2(dobpdc) showed an unusual increase in CO2 uptake on increasing the temperature and selective adsorption of CO2 over water vapors.