Highly Efficient Luminescent Metal Organic Framework for the Simultaneous Detection and Removal of Heavy Metals from Water.
We have designed and synthesized an isoreticular series of luminescent metal organic frameworks (LMOFs) by incorporating a strongly emissive molecular fluorophore and functionally diverse colinkers into Zn based structures. The three dimensional porous networks of LMOF 261, 262, and 263 represent a unique/new type of nets, classified as a 2 nodal, (4,4) c net (mot e type) with 4 fold, class IIIa interpenetration. All compounds crystallize in a body centered tetragonal crystal system (space group I41/a) A systematic study has been implemented to analyze their interactions with heavy metals. LMOF 263 exhibits impressive water stability, high porosity, and strong luminescence, making it an excellent candidate as a fluorescent chemical sensor and adsorbent for aqueous contaminants. It is extremely responsive to toxic heavy metals at a parts per billion level (3.3 ppb Hg2+ 19.7 ppb Pb2+ and demonstrates high selectivity for heavy metals over light metals, with detection ratios of 167.4 and 209.5 for Hg2+/Ca2+ and Hg2+/Mg2+ respectively. Mixed metal adsorption experiments also show that LMOF 263 selectively adsorbs Hg2+ over other heavy metal ions in addition to light metals. The Pb2+ KSV value for LMOF 263 (55,017 M 1) is the highest among LMOFs reported to date, and the Hg2+ KSV value is the second highest (459,446 M 1) LMOF 263 exhibits a maximum adsorption capacity of 380 mg Hg2+/g. The Hg2+ adsorption process follows pseudo second order kinetics, removing 99.1% of the metal within 30 min. An in situ XPS study provides insight to help understand the interaction mechanism between Hg2+ and LMOF 263. No other MOFs have demonstrated such a high performance in both the detection and the capture of Hg2+ from aqueous solution.
ACS applied materials interfaces