Selective and Reversible Capture of Volatile I₂ Modifying As-Synthesized 2D Cd-MOF to 3D

Abstract

Here the selective and reversible capture of molecular I2 (aqueous as well as in the vapor phase) within the flexible two-dimensional (2D) Cd-MOF [constructed from (1,3,5-tri­(1H-benzo­[d]­imidazol-1-yl)­benzene and 1,3,5-tris­(4′-carboxyphenyl-)­benzene; MOF = metal–organic framework] at room temperature with high efficacy is presented, characterized via single-crystal X-ray diffraction. Therein, 1.75 I2/Cd in the aqueous phase and 3.25 I2/Cd in the vapor phase are adsorbed. The competitive adsorption of iodine was done at 80 °C in the presence and absence of water (2 I2/Cd and 1.12 I2/Cd). A structural transformation occurs from a 2D to a three-dimensional (3D) architecture, during I2 capture. Even after the I2 removal (which occurred within ∼5 min in an aqueous/ethanolic KOH solution) it persists in the same 3D architecture. CrO4 2 – and Cr2O7 2 – toxic ions were also captured by the as-synthesized MOF from aqueous solutions of K2CrO4 and K2Cr2O7, respectively. Importantly, the MOF showed a selective I2 adsorption from the mixture of three components (K2CrO4, K2Cr2O7, and I2) in water revealed by single-crystal X-ray diffraction. The selective I2 capture was attributed to several π interactions with the benzimidazole ring and cumulative hydrogen-bonding interactions between iodide and aromatic hydrogens within the proximity of the pores along with the I···O interactions with the carboxylate oxygens as well.

A bifunctionalised Pb-based MOF for iodine capture and dye removal

“…8 Recently, metal-organic frameworks (MOFs) have emerged as potential candidates to adsorb radioactive iodine and dyes. 9,10 The presence of a secondary building unit (SBU) affords a potential synthetic strategy to design a variety of MOFs with robust and multi-purpose properties. 11 Meanwhile, the dimension of MOFs is one of the most influen-tial parameters.…”

Energy‐Efficient Iodine Uptake by a Molecular Host⋅Guest Crystal

“…[60,61] While I 2 storage requires high capacity, I 2 capture needs high selectivity in real conditions. Most porous materials adsorb water from ambient humidity posing several issues for I 2 adsorption (material stability, uptake competition) but the problem of I 2 /H 2 O selectivity has only been seldom studied [62][63][64][65][66] compared to the capture of other gases where the field is more mature (i.e. CO 2 ).…”

Reversible anion-dependent iodine uptake in nonporous pseudopolymorphic coordination polymers

“…[51][52][53][54] Uptake and isolation of radioactive iodine isotopes such as 129 I and 131 I, the most critical nuclear fission products, are important subjects. [55][56][57][58][59][60] Uncontrolled release of iodine, due to its volatility, toxicity and durability, could be a threat to the human metabolism and it may cause thyroid cancer, leukemia, and other diseases. [61][62][63] There are several feasible adsorbents, such as zeolites, [64][65][66] microporous polymers, [67][68][69] porous aromatic frameworks, [70][71][72] covalent organic frameworks (COFs), 73,74 hydrogen-bonded organic frameworks (HOFs), 75,76 chalcogenide aerogels, 77 metalorganic frameworks (MOFs) [78][79][80][81][82][83][84] and porous coordination polymers (PCPs) [85][86][87] which were used for the removal of I 2 .…”