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

Here the selective and reversible capture of molecular I-2 (aqueous as well as in the vapor phase) within the flexible twodimensional (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 I-2/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 degrees C in the presence and absence of water (2 I2/Cd and 1.12 I-2/Cd). A structural transformation occurs from a 2D to a three-dimensional (3D) architecture, during I-2 capture. Even after the I-2 removal (which occurred within similar to 5 min in an aqueous/ethanolic KOH solution) it persists in the same 3D architecture. CrO42- and Cr2O72- 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 I-2) in water revealed by single-crystal X-ray diffraction. The selective I-2 capture was attributed to several p 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 center dot center dot center dot O interactions with the carboxylate oxygens as well.

Automated summary

This study demonstrates the selective capture of molecular I-2 using a flexible two-dimensional Cd-MOF at room temperature, with a structural transformation observed during the capture process. Additionally, the MOF was also able to capture toxic ions CrO42- and Cr2O72- from aqueous solutions, showcasing its versatile adsorption capabilities.