Anionic Lanthanide Metal–Organic Frameworks: Selective Separation of Cationic Dyes, Solvatochromic Behavior, and Luminescent Sensing of Co(II) Ion

Abstract

Four new microporous isostructural anionic lanthanide metal-organic frameworks (Ln-MOFs), [(CH)NH][Ln(TATAT)(HO)]· x(solvent) {Ln = Tb, Eu, Dy, and Gd; HTATAT = 5,5',5″-(1,3,5-triazine-2,4,6-triyl)tris(azanediyl)triisophthalate}, were successfully constructed. The Ln-MOFs are three-dimensional (3D) anionic frameworks and have two sizes of square channels (8.9 × 8.9 Å and 4.3 × 4.3 Å) with a Lewis basic nitrogen-decorated pore environment. The 3D frameworks of Ln-MOFs can be simplified as (4,6)-connected she networks. Because of the anionic framework properties, Ln-MOFs can efficiently select and separate cationic dyes in the presence of anionic or neutral dyes of similar sizes. The adsorption amounts of methylene blue for Tb-MOF, Eu-MOF, Dy-MOF, and Gd-MOF are 147, 141, 133, and 143 mg g, respectively. Moreover, Tb-MOF and Eu-MOF allow easy detection and identification of ethanol, acetonitrile, and diethyl ether through solvatochromism. Diethyl ether vapor also rapidly changes the colors of Tb-MOF and Eu-MOF. The photoluminescence experiments show that the absolute quantum yields of Tb-MOF (upon excitation at 341 nm), Eu-MOF (upon excitation at 396 nm), Dy-MOF (upon excitation at 341 nm), and Gd-MOF (upon excitation at 370 nm) are 32.5%, 11.0%, 2.1%, and 7.1%, respectively. In addition, Tb-MOF can detect Co ion with high selectivity and quenching efficiency of 87%.

Syntheses and Properties of Three Types of 3,4‐Dichlorobenzoate‐based Ni(II)‐Ln(III) Heterometallic Clusters

“…The excitation and emission spectra of 3 (Ni 2 Eu 2 ) are shown in Figure . In the excitation spectrum, a weak broad band in the domain of 320–350 nm is attributed to the π–π* transitions of organic ligands, and several narrow bands located at 362 ( 7 F 0 → 5 D 4 ), 384 ( 7 F 0 → 5 G 2 ), 394 ( 7 F 0 → 5 L 6 ), 415 ( 7 F 0 → 5 D 3 ), and 465 ( 7 F 0 → 5 D 2 ) nm correspond to the f→f transitions of Eu(III) . The emission spectrum excited at 394 nm displays four characteristic peaks of Eu(III) at 593 ( 5 D 0 → 7 F 1 ), 617 ( 5 D 0 → 7 F 2 ), 654 ( 5 D 0 → 7 F 3 ), and 701 ( 5 D 0 → 7 F 4 ) nm .…”

Recent Advances in Nanocomposite Luminescent Metal-Organic Framework Sensors for Detecting Metal Ions

“…The prepared Tb-MOFs, [(CH 3 ) 2 NH 2 ] 1.5 [Tb 1.5 (TATAT)(H 2 O) 4.5 ]•x(solvent), where H 6 TATAT = 5,5′,5″-(1,3,5-triazine2,4,6-triyl)tris(azanediyl)triisophthalate, can detect a Co 2+ ion with high selectivity and quenching efficiency of 87%. [228] The major findings on metal ion detection using lanthanidebased metal organic framework luminescent sensors are summarized in Table 3. 138 Å × 6.24 Å, able to accommodate Fe 3+ , while it interacts weakly with Fe 2+ because of its larger size, which facilitates its leaching.…”

A Dy(iii)–organic framework as a fluorescent probe for highly selective detection of picric acid and treatment activity on human lung cancer cells

“…In these MOFs, those compounds based on lanthanide metal centers have become a new research object due to their unique characteristics of long emission life, high color purity, and a large displacement of stokes. Nevertheless, it is challenging to synthesize the Ln-MOFs because they possess a high number of coordinations and they have a tendency to coordinate with the ligand of oxygen donor that contains more flexibility and higher number of coordinations [15][16][17]. In addition, some Ln-MOFs could not keep their integrality framework in water, which restricts their further applications.…”