Anion-Induced Structures and Luminescent Properties of Chiral Lanthanide−Organic Frameworks Assembled by an Achiral Tripodal Ligand

Mixed-Ligand-Regulated Self-Enhanced Luminous Eu-MOF as an ECL Signal Probe for an Oriented Antibody-Decorated Biosensing Platform

The self-luminescence behavior of lanthanide MOFs (Ln-MOFs) due to the unique antenna effect is considered to be a promising electrochemiluminescence (ECL) emission for biosensors. It is more challenging for Ln-MOFs on account of the difficulty to stimulate Ln ions with the desired energy-transfer efficiency to produce stronger ECL emissions at a low potential. Here, guided by a second ligand-assisted energy-transfer strategy, we present an efficient self-enhanced luminescence mixed-ligand Eu-MOF as an ECL signal probe for an oriented antibody-decorated biosensing platform with a low detection limit and a broad detection range. Diamino terephthalic acid (NH₂-H₂BDC) and 1,10-phenanthroline (Phen) were selected as the first and second ligands, respectively, to form highly conjugated structures, as well as suppress the nonradiative energy transfer. Impressively, Phen precisely adjusts the energy gap between the triplet ligand and the excited state of Eu³⁺, realizing the self-enhancement of ECL efficiency of the Eu-MOF. The mixed ligand adjusted the molar ratio to obtain the stable and strong ECL signal at a lowered triggering potential (0.83 V). In addition, FeCo@CNT features densely active FeCo sites along with a rich hierarchy conductive carbon nanotube (CNT) network, which is efficiently a co-reaction accelerator to produce more TPA^•+ radicals to accelerate the reduction process of the Eu-MOF for achieving the ECL emission amplification. FeCo@CNT with heptapeptide HWRGWVC (HWR) constructed a matrix biosensing interface that allowed the fragment antigen-binding (Fab) regions to target specific antigens and enhance the incubation efficiency. The present study has gone some way toward designing a self-enhanced luminous Eu-MOF, thus giving new fresh impetus to develop high-performance ECL emitters for biological analysis.

Two luminescent film sensors constructed from new lanthanide coordination polymers for ratiometric detection of Zn2+ and NH3 in water and their white emission properties

Two luminescent film sensors constructed from new lanthanide coordination polymers based on a new tetra-monodentated ligand for ratiometric detection of Zn2+ and NH3 in water were developed.

Rare-earth metal–organic frameworks: from structure to applications

In the past 30 years, rare-earth metal–organic frameworks (MOFs) have been gaining attention owing to their diverse chemical structures, and tunable properties.

Anion-induced 3d–4f luminescent coordination clusters: structural characteristics and chemical fixation of CO2 under mild conditions

Anion-induced clusters with luminescence exhibit excellent catalysis to transform CO₂ into cyclic carbonates under mild conditions.

Luminescent rare-earth-based MOFs as optical sensors

This perspective article highlights the basics and applications of luminescence-based sensing of hazardous chemicals, pH, and temperature using rare-earth-based metal–organic frameworks.

Spectral and dynamical properties of a Zr-based MOF

We report on the spectra and dynamics of a Zr-naphthalene dicarboxylic acid (Zr-NDC) MOF in different diluted solvent suspensions and in a concentrated tetrahydrofuran (THF) one. In a diluted diethyl ether (DE) suspension, we observed intraparticle excimer formation between neighboring naphthalene organic linkers, leading to a red-shifted broad band in the emission spectrum and to a dynamics composed of three components τ1 = 650 ps, τ2 = 3.7 ns and τ3 = 13.9 ns, assigned to the excimer photoproduction, monomer and excimer lifetimes, respectively. Furthermore, both absorption and emission spectra show a blue shift in more polar solvents characterized by the solvent polarity function f(ε,n). We also observed changes in the excimer formation time (490-840 ps) probably due to a variation in the MOF structural fluctuation induced by solvent filling. The global fluorescence quantum yield of these suspensions is around 0.30 ± 0.05. At higher concentrations of the MOF particles, we observed the absorption and emission signals of aggregates having an intercrystal excimer formation in ∼ 5 ps in a THF suspension, ∼ 100 times shorter than that observed in a diluted one. Our results give the spectral and dynamical properties of a Zr-NDC MOF in solvent suspensions, opening the way to further studies of these kinds of MOFs interacting with fluorescent dyes for possible photonic applications.

Chirality detection of two enantiomorphic 3D lanthanide coordination polymers by vibrational circular dichroism spectra

Two enantiomorphic 3D lanthanide coordination polymers of {[Dy5(L)4(H2O)10][Dy(H2O)7][Na(H2O)5]}·(ClO4)7·(H2O)15 (1a for R and 1b for S) with chiral helical chains were synthesized based on an achiral ligand N-(2-hydroxyethyl)ethylenediamine-N,N',N'-triacetic acid (H3L) and Dy(ClO4)3. Crystal analysis revealed that 1a and 1b were crystallized in chiral space groups P4132 and P4332, respectively. The absolute configurations of the two structures were evidenced by vibrational circular dichroism (VCD) spectra with one single crystal sample.

Synthesis, characterization and luminescent properties of lanthanide complexes with a novel multipodal ligand

Solid complexes of lanthanide nitrates with an novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2'-furfurylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Sm(III), Eu(III), Tb(III) and Dy(III) nitrate complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level of the ligand indicates that the triplet state energy level (T1) of the ligand matches better the resonance level of Tb(III) than other lanthanide ions.

Crystal structures and luminescent properties of new lanthanide(iii) complexes derived from 2-phenyl-4-pyrimidinecarboxylate

Five novel lanthanide complexes with diverse structural motifs are constructed under different reaction conditions and their photoluminescence properties are studied.

A series of coordination polymers based on varied polycarboxylates and different imidazole-containing ligands: syntheses, crystal structures and physical properties

To investigate the effect of organic ligands on the coordination frameworks, seven nickel(ii) coordination polymers, based on varied polycarboxylates and different imidazole-containing ligands, are synthesized under hydrothermal method.

Unique lanthanide frameworks with 63 topology based on 1,5-naphthalenedisulfonate and 1H-imidazo[4,5-f][1,10]-phenanthroline: syntheses, crystal structure, photoluminescence, and white light emission

Lanthanide complexes with a 6³ net topology were synthesized. White light emissions were realized by the Sm(iii) complex and Ln(iii)-doped Eu(iii) complexes.