White-Light-Emitting Materials and Highly Sensitive Detection of Fe³⁺ and Polychlorinated Benzenes Based on Ln-Metal–Organic Frameworks

Abstract

We employed a rigid bridging-type tetracarboxylic acid molecule, namely, 5,5′-(pyridine-3,5-diyl)­diisophthalic acid (H 4 L; containing two isophthalic acid moieties and one pyridine spacer), to construct three new isomorphic Ln-metal–organic framework (Ln-MOF) materials [(CH3)2NH2]2­[Ln2(L)2­(H2O)2]­·2DMF­·2H2O (Ln3+ = Tb3+ 1, Eu3+ 2, Gd3+ 3; DMF = N,N-dimethylformamide). Since the pyridyl N atom does not coordinate to Ln3+, the larger pores are observed in the three-dimensional networks of 1–3. On the basis of their photoluminescence properties, the white-light-emitting materials 4–7 with longer fluorescence lifetime (millisecond grade) and higher quantum yield (e.g., 48.29% for 5) are fabricated. We also find that the title Ln-MOF materials not only can selectively sense polychlorinated benzenes, but also can highly sensitively detect the Fe3+ ion (K sv = 7.58 × 104 M–1). This should be associated with these three structural factors in 1–3: the larger π-conjugated structure of L4–; the larger porous structures in 1–3; and the existence of uncoordinated N atom on L4–. The test paper experiments reveal that 1 can be made into the test paper (a naked eye probe) to quickly detect the analytes.

Lanthanide Isophthalate Metal‐Organic Frameworks: Crystal Structure, Thermal Behavior, and White Luminescence

“…It then becomes clear that it is possible to modulate the emission of the ligand in relation to the emission of the lanthanide with the excitation wavelength. The excitation wavelength impacts the transferred energy from the ligand to the Ln 3+ cations to allow the coexistence of the ligand and Ln 3+ ions emissions but also to modulate the emission intensities of the three colours [20] . Thus four different excitation wavelengths have been chosen: 258 and 289 nm where the Ln 3+ emission is more intense than the blue ligand emission, 321 nm where the ligand emission is significantly predominant and 312 nm where both emissions are balanced.…”

“…Compared to the inorganic phosphors, LnMOFs compounds offer many advantages for the elaboration of new single‐phase phosphors such as their low temperature synthesis, the efficient antenna effect of the ligand, and the ease to homogenously co‐dope by Ln 3+ cation to generate various emission colors [19] . To conceive a single‐phase white‐luminescent MOF material, a promising approach consists in tuning the proportion of the blue emission of the organic ligand, the green light from Tb 3+ cation and the red color from Eu 3+ cation [11,13–18,20–26] . The tuning of relative proportion of each color can be optimized by adjusting the different amounts of the red and green emitters, but also by an adjustment of the excitation wavelength in order to modulate the blue emission of the ligand and obtain the required white emission [12,20] …”

Dicarboxylate‐Induced Structural Diversity of Luminescent Zn(II)/Cd(II) Metal–Organic Frameworks Based on the 2,5‐Bis(4‐pyridyl)thiazolo[5,4‐d]thiazole Ligand

“…So the diffuse electron densities resulting from these solvent molecules are removed by using the MASK program . The masked guest molecules were quantified through the elemental analyses and thermogravimetric analyses . The relevant crystallographic data are summarized in Table S1.…”

Naphthalimide‐Benzothiazole Conjugate: A Dosimetric Probe for Colorimetric and Fluorometric Detection of Palladium

“…The design and synthesis of new molecular structures for fluorometric and colorimetric detection of biologically and environmentally relevant metal ions is of contemporary interest in supramolecular chemistry . In particular, considerable attention has been paid to the development of optical sensors for palladium, a rare transition noble metal, because of its important role in various biological and chemical activities.…”