Highly Efficient White-Light Emission and UV-Visible/NIR Luminescence Sensing of Lanthanide Metal-Organic Frameworks

摘要

A series of new isostructural lanthanide metal organic frameworks (Ln-MOFs), [Ln(2)(L)(2)(DMAC)(2)]nH(2)O [Ln = La (1), Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), and Tm (8); H4L = 5-(bis (4-carboxybenzyl)amino)-isophthalic acid, DMAC = N,N'-dimethylacetamide], have been isolated. Single-crystal X-ray diffraction analysis reveals that all complexes exhibit a rare (4,8)-connected alb-4,8-P topology with binuclear [Eu-2-(COO)(8)](n) secondary building units as 8 -connected nodes and H4L ligands as 4 -connected nodes. Two mixed-lanthanide analogues of single-lanthanide MOFs were designed and prepared [Ln = La0.93Eu0.02Tb0.05 (9) and Tin(0.47)Eu(0.18)Tb(0.35) (10)] by way of careful regulation of the relative concentration of lanthanide ions which are able to emit pure white light. Luminescent sensing of complexes 3 and 5 has been investigated. Strikingly, complex 5 exhibits an excellent luminescent sensing to TNP with a high K-sv value of 3.58 X 10(4) M-1 and a low detection limit of 4.66 X 10(-4) mM. Complex 3 reveals high selectivity and sensitivity toward benzaldehyde (K-sv of 4.9 X 10(4) M-1; detection limit of 3.4 X 10(-4) mM). It represents the first example of an NIR luminescent MOF for sensing of benzaldehyde.