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In this work, a Mn-based metal−organic framework (MOF) {[H-Phen] 2 [Mn 3 (FDA) 4 (H 2 O) 2 ]•2H 2 O} n (SM-1) has been synthesized solvothermaly using 2,5-furandicarboxylic acid (2,5-FDA) as a linker and 4,7-phenanthroline (4,7-Phen) as a coligand. SM-1 was characterized using elemental analysis, Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), and crystallographic studies. Single-crystal X-ray data reveal that the SM-1 framework is constituted by trinuclear Mn secondary building units (SBUs) as a dianion ([Mn 3 (COO) 6 ] 2− ), 2,5-FDA, and free 4,7-phenanthrolinium cation [H-Phen] + rings containing uncoordinated amino and imino moieties, which provide extra stability to the framework and feasible recognition sites to interact with analytes. Overall, the MOF is anionic in nature, which is counterbalanced by two protonated phenanthrolinium cations, thus giving rise to +2 oxidation states for all three Mn ions. Topological analysis shows that SM-1 has a {4 4 .6 2 } point symbol having a 4-c uninodal net with sql topology. SM-1 is an excellent fluorescent sensor for d 10 heavy metal ions in an aqueous environment. SM-1 developed as a highly sensitive sensor exhibits a fluorescence "turn-on" response for Ag + and Cd 2+ ions and a fluorescence "turn-off" response in the case of Hg 2+ ion with much lower limit of detection (LOD) values. Moreover, SM-1 application is not limited to only sensing, but it can also serve as an adsorbent to capture hazardous substances. Owing to the presence of π-electron-rich moieties and uncoordinated nitrogen atoms in the SM-1 framework, it is also explored for efficient iodine uptake. SM-1 captures iodine reversibly in cyclohexane solution with high adsorption capacity within 36 h. Further, a plausible mechanism of sensing and iodine adsorption was also discussed briefly. As far as we know, this is the first example of a Mn-based anionic MOF functioning as a fluorescent chemosensor to simultaneously detect d 10 heavy metal ions in water and as an adsorbent to trap iodine. Thus, metal− organic chemistry has been employed to develop multifunctional MOF material for the sensing of hazardous metal ions and as an adsorbent for the removal of toxic iodine.

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A 2-Dimensional Pb(II) metal-organic framework, [Pb(bdc)0.5(py-Phen)NO3]n (SM-3) was synthesized under solvothermal conditions utilizing a mixed ligand approach. SM-3 assembled through dinuclear SBUs [Pb2(COO)2]2-, oxygen donor H2bdc = 1,4-benzene dicarboxylic acid,...