With the conflicting problems of pollution due to ammonia emissions and the demand for ammonia, we propose M-2(INA) (M = Cu, Co, Ni, Cd) (INA= isonicotinic acid), a series of materials that exhibit flexible conversion in ammonia adsorption. They can capture both wet and dry ammonia for recycling. The materials were obtained by dehydration of coordination materials M(INA)(2)(H2O)(4) (M = Cu, Co, Ni, Cd) (150 degrees C) at atmospheric pressure for 2 h. M-2(INA) could reversibly transform to the stable coordination compounds M(INA)(2)(H2O)(2)(NH3)(2) by adsorbing ammonia in the presence of moisture. The capacity for pure ammonia could reach 12-13 mmolig. Importantly, these materials could stably retain NH3 at a maximum temperature of 80 degrees C and could regenerate below 150 degrees C with no performance loss. (C) 2015 Elsevier B.V. All rights reserved.