Iodo-functionalization of Zr-UiO-67 metal-organic frameworks: An efficient strategy for I2 uptake and selective detection of I

Zr-based UiO-67(ZBPU) Metal-Organic Frameworks (MOFs) bearing iodo functional groups were synthesized, characterized, and then investigated for I2 capture under solution and gaseous conditions. Consequently, mono- and bi-functional iodo-containing derivatives (ZBPU-I and ZBPU-I2) exhibited remarkable performance compared to the pristine ZBPU, highlighting the versatility of halogen-halogen interactions in I2 uptake. Notably, an iodine uptake capacity of 1260.7 mg.g−1 was recorded for ZBPU-I2 in cyclohexane after 4 h, which is 3.8 times greater than the amount of non-modified ZBPU (329.25 mg.g−1). To the best of our knowledge, this is the highest I2 loading capacity recorded for MOFs in solution phase. Moreover, ZBPU-I2 illustrated reversible I2 uptake and recyclability for four runs. Also, substantial enhancement for iodine vapor capture was observed by increasing the number of iodo functions: I2 adsorptions of 2.6, 2.49, and 3.45 g.g−1 were measured for ZBPU, ZBPU-I and ZBPU-I2, respectively, further proving the effectiveness of MOFs iodo-functionalization strategy in I2 adsorptive improvement. Besides I2, ZBPU-I2 showed significant potential and highly selective application as a fluorescence probe for sensing iodide (I͞). Correspondingly, ZBPU-I2 responded to I͞ by completely overturning the emission spectra from turn-on mode to quenching mode even in the competing presence of various anions. Finally, this study expands the MOFs design toolboxes for efficient I2/ I͞ adsorption.