Flexible Linker Spacer Length Modulation in Cd-Based Metal-Organic Frameworks: Impact on Polarity and Sequestration...

The heightening concerns over an outbreak of hazardous radioiodine from nuclear waste and carbon dioxide emissions from fossil fuels have restricted access to clean water and air. In this work, three Cd-MOFs (1-3) are self-assembled under environment-friendly conditions using i) a polypyridyl linker spanned by a flexible poly(methylene) spacer, and ii) a bent dicarboxylate linker. With a change in the length of the flexible methylene spacer, the dimensionality of the MOFs is tuned between 3D (1) and 2D (2 and 3). The microscopic images reveal that 1 displays larger particle sizes and a more pronounced morphology compared to 2 and 3. These MOFs show high thermal stability (up to 300 °C) and wettability. A controlled polar feature of 1-3 is utilized to achieve a high uptake capacity of iodine (I₂ or I₃ ^-) from water bodies (2.46-2.37 g g^-1) and vapor (3.31-2.65 g g^-1). With remarkable CO₂ uptake by 1-3, the sorbate CO₂ is further fixated into market-value products in quantitative conversions and atom economy under room temperature and solvent-free conditions. A comprehensive theoretical support is provided by configurational biased Monte Carlo (CBMC) simulations to reveal the exact locale and binding energies of the sorbates (I₂, CO₂, and epoxide) toward these MOFs.