Search

The synthesis of dynamic chiral lanthanide complex emitters has always been difficult. Herein, we report three pairs of dynamic chiral EuIII complex emitters (R/S-Eu-R-1, R = Et/Me; R/S-Eu-Et-2) with aggregation-induced emission. In the molecular state, these EuIII complexes have almost no obvious emission, while in the aggregate state, they greatly enhance the EuIII emission through restriction of intramolecular rotation and restriction of intramolecular vibration. The asymmetry factor and the circularly polarized luminescence brightness are as high as 0.64 (5D0 → 7F1) and 2429 M−1cm−1 of R-Eu-Et-1, achieving a rare double improvement. R-Eu-Et-1/2 exhibit excellent sensing properties for low concentrations of CuII ions, and their detection limits are as low as 2.55 and 4.44 nM, respectively. Dynamic EuIII complexes are constructed by using chiral ligands with rotor structures or vibration units, an approach that opens a door for the construction of dynamic chiral luminescent materials. Chiral luminescent materials are of increasing interest in various applications, but achieving a desirable balance of properties can be challenging. Here, the authors report the development of Eu-based complexes with chiral luminescence and aggregation induced emission. [ABSTRACT FROM AUTHOR]

Lanthanide doping is an effective strategy for modulating the emission of emitters. Herein, by changing the cluster composition to control the energy transfer pathway, the application potential of high-nuclearity lanthanide cluster (HLC) as white-light emitter has been confirmed for the first time. Specifically, by precisely controlling the proportion of GdIII, TbIII, and EuIII ions in reactants, we obtained a spherical heterotrimetallic nanocluster Gd10Tb12Eu10, a white-light emitter with quantum yield (QY) of 12.58% and lifetime of 327.14 µs. High-resolution electrospray ionization mass spectrometry (HRESI-MS) demonstrates that homometallic nanoclusters Ln32 (Ln = Gd, Tb, and Eu) are tetracationic clusters and are highly stable in solution. The peripheral dense organic ligands provide a protective layer for the cluster core, which improves the stability of Ln32 in aqueous solution, avoids the contact between metal centers and bioactive molecules, and greatly reduces the biological toxicity. In cell imaging experiments, cationic clusters Ln32 are mainly localized on the cell membrane with negative charge distribution. As far as we know, this is the first time that spherical lanthanide nanoclusters have been used for membrane imaging of living cell, opening the door for the application of HLCs in biological imaging. [ABSTRACT FROM AUTHOR]

In the past two decades, tremendous progress has been made in the field of single-molecule magnets (SMMs), which not only achieves breakthroughs in various key indicators (flipping energy barrier and hysteresis temperature), but also expands SMMs of various types (3d, 4f, 3d–4f and 5f) and different connection methods. Among the many different types of SMM mentioned above, the SMM based on the 4f metal center has made the biggest breakthrough. Introducing 3d metal ions into lanthanide complexes to form 3d–4f heterometallic complexes can promote strong magnetic exchange between multiple metal centers, resulting in magnetic properties different from 3d and 4f complexes. Therefore, the expansion of the structure and magnetic properties of 3d–4f heterometallic complexes can promote the progress in the field of SMM. In this review, we summarize the structure and magnetic properties of 3d–4f heterometallic complexes formed by different types of organic ligands. [ABSTRACT FROM AUTHOR]

Rapid kinetics, complex and diverse reaction intermediates, and difficult screening make the study of assembly mechanisms of high-nuclearity lanthanide clusters challenging. Here, we synthesize a double-cage dysprosium cluster [Dy60(H2L1)24(OAc)71(O)5(OH)3(H2O)27]·6H2O·6CH3OH·7CH3CN (Dy60) by using a multidentate chelate-coordinated diacylhydrazone ligand. Two Dy30 cages are included in the Dy60 structure, which are connected via an OAc− moiety. The core of Dy60 is composed of 8 triangular Dy3 and 12-fold linear Dy3 units. We further change the alkali added in the reaction system and successfully obtain a single cage-shaped cluster [Dy30(H2L1)12(OAc)36(OH)4(H2O)12]·2OH·10H2O·12CH3OH·13CH3CN (Dy30) with a perfect spherical cavity, which could be considered an intermediate in Dy60 formation. Time-dependent, high-resolution electrospray ionization mass spectrometry (HRESI-MS) is used to track the formation of Dy60. A possible self-assembly mechanism is proposed. We track the formation of Dy30 and the six intermediate fragments are screened. High-nuclearity lanthanide clusters can exhibit interesting properties such as magnetism, but the mechanisms by which they assemble are poorly understood. Here, the formation of two dysprosium nanoclusters containing 30 or 60 atoms is followed over time by mass spectrometry and proposed to follow a seven-step assembly mechanism. [ABSTRACT FROM AUTHOR]

N-Methylbenzimidazole-2-methanol (L) and Ln(NO3)3·6H2O are dissolved in a mixed solvent of methanol and acetonitrile and then reacted at 80 °C to obtain [Ln3(L)5(NO3)4] (Ln3, Ln = Gd, Tb). In Ln3, three L− are located in the same plane as the three Ln3+ ions, and the other two L− are located above and below the plane, respectively. Two of the four NO3− ions are respectively coordinated with two Ln3+, and the other two are coordinated with one Ln3+ ion, which results in the asymmetry of the above-described triangular shape Ln3. When the Ln3 single crystal was tested by Electrospray Ionization Mass Spectrometry, the main frame [Ln3L5(NO3)3]+ was found to be stable, only one NO3−ion was lost. As the energy of the ion source increases, we observe the gradual fragmentation of the triangular shape Ln3, and propose that the fragmentation mechanism is: Ln3L5 → Ln3L4 → Ln2L4 → Ln2L3 → Ln2L2 → LnL. This provides the basis for the assembly of triangular shaped Ln3 clusters. For the first time, the magnetocaloric effect (MCE) of triangular Gd3 clusters was studied and it exhibited a large MCE of 10.65 J kg−1 K−1 at 7 K for ΔH = 5 T. [ABSTRACT FROM AUTHOR]

A tandem reaction of pyridin-2-ylmethanamine (L1′) with 8-hydroxyquinoline-2-carbaldehyde (HL1) assisted by FeCl3 was observed to give the new nitrogen heterocycle HL3 (HL3=2-(imidazo[1,5-a]pyridin-3-yl)quinolin-8-ol) as its Fe(III) complex, [Fe(L3)Cl2] (Fel). Electrospray ionization mass spectrometry (ESI-MS) reveals its formation involves three steps: (1) coordination of both HL1 and Ll′ to Fe, (2) aldehyde-amine coupling, and (3) ring closure. The results of electronic absorption spectroscopy, cyclic voltammetry, and density functional theory (DFT) calculations show the proximity of the optical transition energy to that of the excitation of 3O2 to 1O2, which prompted us to explore its application as a photosensitizer for photodynamic therapy (PDT). Photo-toxicity studies show that Fel exhibits the highest anti-proliferation efficiency in human breast cancer MDA-MB-231 cells under light irradiation. Moreover, studies with orthotopic models of breast cancer further expounded the anti-tumor activity of Fe1 with no significant toxicity to other organs and low retention in the body. [ABSTRACT FROM AUTHOR]

Rapid kinetics, complex and diverse reaction intermediates, and difficult screening make the study of assembly mechanisms of high-nuclearity lanthanide clusters challenging. Here, we synthesize a double-cage dysprosium cluster [Dy 60 (H 2 L 1 ) 24 (OAc) 71 (O) 5 (OH) 3 (H 2 O) 27 ]·6H 2 O·6CH 3 OH·7CH 3 CN (Dy 60 ) by using a multidentate chelate-coordinated diacylhydrazone ligand. Two Dy 30 cages are included in the Dy 60 structure, which are connected via an OAc - moiety. The core of Dy 60 is composed of 8 triangular Dy 3 and 12-fold linear Dy 3 units. We further change the alkali added in the reaction system and successfully obtain a single cage-shaped cluster [Dy 30 (H 2 L 1 ) 12 (OAc) 36 (OH) 4 (H 2 O) 12 ]·2OH·10H 2 O·12CH 3 OH·13CH 3 CN (Dy 30 ) with a perfect spherical cavity, which could be considered an intermediate in Dy 60 formation. Time-dependent, high-resolution electrospray ionization mass spectrometry (HRESI-MS) is used to track the formation of Dy 60 . A possible self-assembly mechanism is proposed. We track the formation of Dy 30 and the six intermediate fragments are screened., (© 2020. The Author(s).)