Synthesis and Characterization of Two Cd2+-Based Metal-Organic Frameworks and Their Ammonia Adsorption Performance

The coordination-driven self-assembly of Cd2+ ions with 3-aminoisonicotinic acid yielded two metal-organic frameworks (3-AIN-Cd-MOF-1 and 3-AIN-Cd-MOF-2) with distinct channels in the frameworks. The single crystal X-ray diffraction revealed a non-porous, close-packed framework for 3-AIN-Cd-MOF-1 and complex hexagonal open channels for 3-AIN-Cd-MOF-2. FTIR spectroscopy, powder X-ray diffraction, and thermogravimetry were discussed in detail for these compounds. 3-AIN-Cd-MOF-1 exhibits exceptional water stability, while 3-AIN-Cd-MOF-2 displays a high ammonia adsorption ability with 11.0 mmol/g at 1 atm and room temperature. In situ infrared spectroscopy was further used to monitor the ammonia adsorption procedure in 3-AIN-Cd-MOF-2 for a deeper understanding.