Complexing Eu³⁺/Tb³⁺ in a Nanoscale Postmodified Zr-MOF toward Temperature-Modulated Multispectrum Chromism

Abstract

In recent years, extensive research has been directed toward the successful preparation of nanoscale luminescent thermometers with high sensitivities operative in a broad temperature range. To achieve this goal, we have devised a unique design and facile multistep synthesis of Zr-ctpy-NMOF@ Tb x Eu y compounds by confining Ln-complexes (Ln = Eu 3+ /Tb 3+ ) into a robust nanoscale Zr-NMOF (MOF-808) via postsynthetic modification. Covalent grafting of 4-(4′-carboxyphenyl)-2,2′:6,2″terpyridine ligand (ctpy) with a high triplet state energy and corresponding immobilization of bimetallic Ln 3+ ions resulted in yellow light-emitting Zr-ctpy-NMOF@Tb 1.66 Eu 0.14 to achieve a sensitivity of 5.2% K −1 (thermal uncertainty dT < 1 K) operative over a broad temperature range of 25−400 K. To defeat the odds related to the detection of minute temperature changes using luminescent materials, we prepared a white light-emitting Zr-ctpy-NMOF@Tb 1.4 Eu 0.31 that showed temperature-modulated multispectrum chromism where the color drastically changes from green (at 25 K, Q.Y.: 20.21%) to yellowish-green (at 200 K, Q.Y.: 23.13%) to white (at 300 K, Q.Y.: 26.4%) to orange (at 350 K, Q.Y.: 26.93%) and finally red (at 400 K, Q.Y.: 28.2%) with a high energy transfer efficiency of 49.8%, which is further supported by electron−phonon coupling.

Post engineering of a chemically stable MOF for selective and sensitive sensing of nitric oxide

“…1c and S3†). 42,43,46 This suggests the coordination bridging of BTC ligands with Zr( iv )–metal cations. Furthermore, the highly porous nature of MOF-808 was investigated by N 2 sorption measurement at 77 K temperature.…”

“…40,41 The presence of a benzene core ligand together with d 10 metal cations makes MOF-808 a luminescent probe, which is further utilized as a sensory material. 42,43 Moreover, the Zr 6 -oxo cluster of MOF-808 offers tunable functionality in the framework by allowing simple yet versatile, facile induction of diverse functional moieties in its secondary building unit (SBU) by exchanging the formate linker. [42][43][44][45] Furthermore, MOF-808 was found as an ideal MOF candidate for the fabrication of mixed-matrix-membranes (MMMs), because of its special cluster coordination and the ensuing simplicity of adding more functional molecules.…”

Lanthanide-Directed Luminescent “Soft” Coordination Polymer Gels: White Light Emission, Anticounterfeiting, and Thin-Film-Based Sensing

“…Further, it is known that carboxylic acid-containing linkers are excellent chelating motifs for Ln­(III) to induce an antenna effect. Importantly, the calculated triplet state level of the BTT ligand with the help of the density functional theory is 30,068 cm –1 , which is suitable to sensitize the Tb­(III) ions as well as Eu­(III) ions (Figure S9, Supporting Information). − The emission spectra of all the CPG materials were recorded at 321 nm excitation wavelength. The PL spectrum of terbium-containing CPG material Tb@BTT exhibits strong emission bands at 492, 546, 587, and 623 nm, which are attributed to 5 D 4 → 7 F 6 , 5 D 4 → 7 F 5 , 5 D 4 → 7 F 4 , and 5 D 4 → 7 F 3 transitions of Tb­(III) ions (Figure c).…”

Recent advances in the development of europium(iii) and terbium(iii)-based luminescent supramolecular metallogels

“…with diverse applications such as self-healing, catalytic, chemo-sensing, multi-stimuli-responsive, luminescent and white-light-emitting materials. 5,30–34,48,58,59,77…”

“…with diverse applications such as self-healing, catalytic, chemo-sensing, multistimuli-responsive, luminescent and white-light-emitting materials. 5,[30][31][32][33][34]48,58,59,77 Nowadays metal directed supramolecular gels are receiving pronounced attention as metallogels are more ordered than the corresponding supramolecular gels with superior function and complexity such as electronic, redox, magnetic, and optical properties. [35][36][37][38][39][40][41][42] Metallogels with lanthanide ions are especially more attractive due to the lanthanide ion's unique optical properties such as stable and sharp emission peaks, long luminescence lifetime (in the millisecond range), resistance to photobleaching, and intense luminescence.…”