Water modulated synthesis of highly crystalline CAU-1-NH2

The effect of water in the solvent on the crystallization behavior of CAU-1-NH 2 , an Al-based metal–organic framework, was studied. CAU-1-NH 2 was synthesized from AlCl 3 ∙6 H 2 O and 2-aminoterephthalic acid in methanol with a small amount of water. The crystallinity and particle size of CAU-1-NH 2 increased and the nucleation frequency decreased upon the addition of a very small amount of water (less than 3.0 wt%). Thermogravimetric analysis revealed that the number of missing linkers increased from 0% to 5.36% with the addition of water. These results suggest that a small amount of water functioned as a modulator during synthesis using organic solvents. The BET surface area increased from 1017 to 1060 m 2 g −1 , and the amount of adsorbed CO 2 increased from 182 cm 3 (STP) g −1 to 222 cm 3 (STP) g −1 at 600 kPa at 298 K with the addition of 3.0 wt% water to the solvent, suggesting that the addition of water is a simple method to improve the adsorption capacity of CAU-1-NH 2 .