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The lanthanide metal organic framework compounds [Ln(BPTA)1.5(Bpy)]·0.5DMF (Ln = Y, Eu, Gd, Tb, Dy; 1a–5a) and [Ln(BPTA)1.5(Phen)]·0.5DMF (Ln = Y, Eu, Gd, Tb, Dy; 1b–5b) were prepared by employing 2,5-bis(prop-2-yn-1-yloxy)terephthalic acid (2,5-BPTA) as the primary ligand and 2,2′-bipyridine (1a–5a) and 1,10-phenanthroline (1b–5b) as the secondary ligands. Single-crystal structural studies on [Gd(BPTA)1.5(Bpy)]·0.5DMF (3a) and [Dy(BPTA)1.5(Phen)]·0.5DMF (5b) indicated that the compounds have a two-dimensional structure. The Y compound exhibits blue emission, and the other compounds exhibit emission in the expected regions (λex = 350 nm). White light emission was achieved by careful mixing of the red (Eu3+) and green (Tb3+) components in the blue emitting Y compound. Thus, Y0.96Tb0.02Eu0.02 (bpy) and Y0.939Tb0.06Eu0.001 (phen) were found to show white emission when excited using a wavelength of 350 nm. The introduction of N–N-containing ancillary ligands (i.e., bpy and phen) increased the overall quantum yield (QY) of white light emission to 31% and 43%, respectively. The high QY observed for the Tb and Eu compounds was found to be sensitive and selective for the fluorometric detection of azinphos-methyl pesticide and trinitrophenol (TNP) in an aqueous medium at the ppb level. The same behaviour was observed when utilising the compounds as onsite paper strip sensors. Their magnetic properties were also studied, revealing for the Tb and Dy derivatives slow relaxation of the magnetisation at low temperature. The present study highlights the usefulness of rigid π-conjugated molecules such as 2,2′-bipyridine and 1,10-phenanthroline in enhancing the many utilities of rare-earth-containing MOFs towards white light emission, the sensing of harmful and dangerous substances and magnetic properties. [ABSTRACT FROM AUTHOR]

Urgent demand for the prevention and diagnosis of physiological diseases is driving the development of biomarkers and physiological temperature fluorometric sensors. In this paper, a rare trinuclear lanthanide metal–organic framework (MOF), [(CH3)2NH2][Eu3(μ3-OH)(2,6-NDC)3(HCOO)3]·(solv)x (Eu(2,6-NDC), where 2,6-H2NDC = 2,6-naphthalenedicarboxylic acid) was synthesized using reticular chemistry via reducing the symmetry of the organic ligand from axisymmetric 1,4-naphthalenedicarboxylic acid (1,4-H2NDC) to non-axisymmetric 2,6-H2NDC. Eu(2,6-NDC) shows exceptional chemical and thermal stability in acid–base solutions, PBS solution, and boiling water, and even under an air atmosphere up to 300 °C. As-synthesized Eu(2,6-NDC) exhibits ratiometric detection abilities for P1,P5-di(adenosine-5′) pentaphosphate (Ap5A), for use as a biomarker of dry eye disease, with a limit of detection (LOD) of 0.031 μM, as well as excellent anti-interference properties. As far as is known, it is the first Ap5A sensor based on MOFs. In addition, the results show that the ratiometric parameters of co-doped Eu0.001Gd0.999(2,6-NDC) deliver a good linear luminescence response to physiological temperatures (20–60 °C) with high sensitivity. [ABSTRACT FROM AUTHOR]

Cation exchange, a facile and non-destructive post-synthetic modification method, is applied to [(Me)4N]2[Pb6K6(m-BDC)9(OH)2]·H2O (1) (1,3-H2BDC = 1,3-benzenedicarboxylic acid) to prepare a series of lanthanide functionalized metal–organic frameworks. The fluorescence properties of Ln3+@1 (Ln = Eu, Tb, Sm and Dy) are investigated. The results demonstrate that the framework of 1 is capable of sensitizing both Eu3+ and Tb3+ ions effectively. Remarkably, the rapid and stable fluorescence sensitization of Eu3+@1 can be observed in the presence of fleroxacin in aqueous solution, indicating that the hybrid system can be designed as a highly sensitive and selective probe for fleroxacin. As a novel "turn-on" fluorescent probe, Eu3+@1 is regarded as a promising candidate for applications in clinical diagnosis, due to its merits of high antidisturbance, chemical stability and a low detection limit (43.91 ng mL−1). In this paper, the practical application of luminescent Eu3+@1 is highlighted, and its possible sensing mechanism is also described. [ABSTRACT FROM AUTHOR]