This study explores the potential of Zn(NH3)(CO3) for selective CO2 separation. It develops a novel highly controllable single-pot synthesis approach based on urea hydrolysis and solvothermal aging to increase the feasibility of synthesizing Zn(NH3)(CO3), determines the structure of Zn(NH3)(CO3) in detail through single crystal X-ray diffraction and powder X-ray diffraction analyses, and performs adsorption analyses for the compound using N-2, H-2, and CO2 as adsorptives. Structural analyses show Zn(NH3)(CO3) to have an inorganic helical framework that consists of a small helix of (ZnOCO)(2) and a big helix of (ZnOCO)(4) with two ammines (NH3) pendant from every other zinc. In terms of adsorption capacity and CO2 selectivity, Zn(NH3)(CO3) adsorbed 0.550 mmol CO2 at 293 K and 4500 mmHg, but only 0.047 mmol g(-1) N-2 and 0.084 mmol g(-1) H-2 at the same temperature and pressure. This behavior demonstrates considerable equilibrium selectivities - 31 and 63 - for separating CO2 from H-2 and CO2 from N-2, respectively. During adsorption, the pendant ammines act as the gates of check-valves: applied pressure opens the gates for adsorption, and during desorption, the gates are closed, trapping the adsorbates, until a reduction of pressure to near-atmospheric levels. Therefore, Zn(NH3)(CO3) exhibits low-pressure H-4 hysteresis, indicating that the Zn(NH3)(CO3) framework can achieve gas storage at near-atmospheric pressures. Additionally, the compound proves structurally stable, with an adsorption decrease of 0.8% after 20 adsorption desorption cycles-a factor that, considered with the other characteristics of Zn(NH3)(CO3), renders this compound a potential candidate for separating CO2 from H-2 and N-2. (C) 2016 Elsevier B.V. All rights reserved.