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Anhydrous Lanthanide MOFs and Direct Photoluminescent Sensing for Polyoxometalates in Aqueous Solution
Author(s) -
Bo QiBing,
Zhang HaiTao,
Wang HongYan,
Miao JinLing,
Zhang ZhenWei
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201303677
Subject(s) - lanthanide , microporous material , isostructural , anhydrous , aqueous solution , powder diffraction , europium , materials science , photoluminescence , chemistry , thermogravimetric analysis , crystallography , inorganic chemistry , crystal structure , ion , organic chemistry , optoelectronics
Abstract New anhydrous lanthanide metal–organic frameworks (MOFs) [Pr(tip) 1.5 ] 2 n ( tip‐Pr ), [Nd(tip) 1.5 ] 2 n ( tip‐Nd ), [Eu(tip) 1.5 ] 2 n ( tip‐Eu ), and [Eu(OH)(mip)] n ( mip‐Eu ) (tip=5‐ tert ‐butylisophthalate anion, mip=5‐methylisophthalate ion), have been hydrothermally synthesized and structurally characterized by elemental analyses, FT‐IR spectroscopy, single‐crystal X‐ray diffraction, thermal gravimetric analysis/differential thermal analysis (TG/DTA), and X‐ray powder diffraction (XRPD) techniques. MOFs tip‐Pr , tip‐Nd , and tip‐Eu are isostructural anhydrous compounds, and exhibit an unprecedented 3D microporous structure with hexagonal channel arrays. The selectively prepared MOF mip‐Eu presents an interpenetrated 3D microporous architecture containing the hydroxyl cluster chains. Solid‐state photoluminescence properties at room temperature indicate that both tip‐Eu and mip‐Eu display the characteristic of the Eu 3+ ion spectrum dominated by the 5 D 0 → 7 F J ( J =0‐4) transition. Compared with mip‐Eu , tip‐Eu displays the very high solid‐state quantum yield (0.62±0.03) and longer lifetime value (0.94±0.01 ms), which is due to the absence of the hydroxyl groups from the solid‐state structure of tip‐Eu . More importantly, a new method to directly investigate the potential of solid‐state lanthanide MOFs for ionic sensing in aqueous solutions has been developed, and successfully applied it to study the potential sensing function of tip‐Eu for polyoxometalates (POMs). The possible mechanism for the quenching effect of POMs on the fluorescence of tip‐Eu is elucidated by the strongly competitive absorption of the excited light source energy between POMs and tip ligands. The very promise for the highly sensitive sensing for polyoxometalates, together with the characteristic of the reversible fluorescence response, suggest that solid‐state tip‐Eu can be an excellent candidate for the directly photoluminescent detection of POMs in aqueous solutions.