Samples of diamine-appended Mg2(dobpdc) frameworks used for collection of high-throughput isotherm data were prepared following conditions reported previously.23 (link) For each analogue, a solution of 20 v/v% diamine in toluene was stirred over freshly-ground CaH2, and a quantity corresponding to a 10-fold molar excess of diamine per metal site was added to approximately 100 mg of desolvated Mg2(dobpdc) under N2 by syringe or cannula transfer. The slurry was sonicated for 15 min under N2 and left undisturbed under N2 for a minimum of 12 h. The solid was then isolated by filtration in air and washed with 30 mL of dry toluene followed by 30 mL of dry hexanes at room temperature. Prior to adsorption measurements, the samples were desolvated by heating in vacuo at 120 °C for 12 h.
For all subsequent experiments, it was found that identical CO2 adsorption performance could be achieved through direct diamine-grafting of methanol-solvated Mg2(dobpdc), enabling rapid sample preparation by eliminating time-consuming activation of the parent framework. In this rapid procedure, approximately 30 mg of methanol-solvated Mg2(dobpdc) was isolated by filtration, washed with 30 mL of toluene, and submerged in 5 mL of a 20 v/v% solution of diamine in toluene. After 12 h, the solid was isolated by filtration and washed with 30 mL of fresh toluene to remove excess diamine.
Powder X-ray diffraction patterns, infrared spectra, and representative diamine loadings obtained from NMR spectra upon digestion of the material are presented in Figures S3–S4 and Table S2.