Tuning CO₂ Uptake and Reversible Iodine Adsorption in Two Isoreticular MOFs through Ligand Functionalization

Abstract

The synthesis and characterization of two isoreticular metal-organic frameworks (MOFs), {[Cd(bdc)(4-bpmh)]}n⋅2 n(H2O) (1) and {[Cd(2-NH2bdc)(4-bpmh)]}n⋅2 n(H2O) (2) [bdc = benzene dicarboxylic acid; 2-NH2bdc = 2-amino benzene dicarboxylic acid; 4-bpmh = N,N-bis-pyridin-4-ylmethylene-hydrazine], are reported. Both compounds possess similar two-fold interpenetrated 3D frameworks bridged by dicarboxylates and a 4-bpmh linker. The 2D Cd-dicarboxylate layers are extended along the a-axis to form distorted square grids which are further pillared by 4-bpmh linkers to result in a 3D pillared-bilayer interpenetrated framework. Gas adsorption studies demonstrate that the amino-functionalized MOF 2 shows high selectivity for CO2 (8.4 wt % 273 K and 7.0 wt % 298 K) over CH4 , and the uptake amounts are almost double that of non-functional MOF 1. Iodine (I2 ) adsorption studies reveal that amino-functionalized MOF 2 exhibits a faster I2 adsorption rate and controlled delivery of I2 over the non-functionalized homolog 1.

MIL‐53(Al) as a Versatile Platform for Ionic‐Liquid/MOF Composites to Enhance CO2 Selectivity over CH4 and N2

“…MOFs can be synthesized from a wide variety of metal ions and organic linkers, and their chemical and physical properties can be tuned by using postsynthetic modification methods . Several studies have reported that the gas‐adsorption affinity and selectivity of MOFs can be enhanced by incorporating functional groups, such as sulfonic acids and amines, into the pores through ligand modification . In this respect, a relatively recent approach was developed, in which MOFs were combined with ionic liquids (ILs), which are molten salts of organic or inorganic anions and cations .…”

Structural Diversity and Selective CO2 Adsorption of Metal– Organic Frameworks Built with a Flexible Dipyridyl Ligand and Different Carboxylates

“…The frameworks 2 and 3 are exhibiting the higher CO 2 adsorption (38 cm 3 g −1 for 2 and 35 cm 3 g −1 for 3 at 1 bar pressure and 195 K temperature) over the others might be due to the presence of amine decorated channels. Moreover, another basic site present for CO 2 interaction inside the cage is the –NH– group of the linker L . Frameworks 1–5 exhibit selective adsorption of CO 2 over N 2 and CH 4 .…”

Face‐Capped M4L4 Tetrahedral Metal–Organic Cage: Iodine Capture and Release, Ion Exchange, and Electrical Conductivity

“…On the other hand, the increasing risk of radioactive iodine in the waste of the nuclear industry is dangerous to the health of humans, and this waste is very difficult to deal with because of iodine's long half‐life time of 15.7 million years . Recently, the capture of iodine and its derivatives by metal–organic cages (MOCs), metal–organic frameworks (MOFs) or porous coordination polymers (PCPs) has been vigorously investigated, showing fascinating prospects . For example, Zeng's group reported a highly stable MOF which exhibits kinetics of iodine loading and release similar to activated carbon .…”