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Coinage-metal clusters with excellent luminescence properties have attracted considerable interest due to their intriguing structures and potential applications. However, achieving strong near-infrared (NIR) luminescence in these clusters is highly challenging. Here, we have successfully synthesized the first LnIII/CuIbimetallic clusters, formulated as [LnCu54O6Cl3(2-MeO-PhC≡C)36] (ClO4)6(Ln = Yb for YbCu54, Er for ErCu54, and Gd for GdCu54). Single crystal X-ray diffraction showed that the LnCu54clusters have a three-layered core–shell structure, consisting of (LnO6)@Cu18Cl3@Cu36units protected by 36 2-MeO-PhC≡C–ligands. Notably, the YbCu54cluster exhibits significant NIR-II luminescence at 986 nm with the solid quantum efficiency of 33.3%, the highest among Cu clusters with NIR-II emission. This work not only reports the first category of LnIII/CuIclusters but also presents a method to enhance NIR luminescence in coinage-metal clusters through the incorporation of LnIIIions.

Open hollow dodecahedral cage clusters have long been a coveted target in synthetic chemistry, yet their creation poses immense challenges. Here we report two open hollow dodecahedral lanthanide–aluminum (Ln–Al) heterometallic cage clusters, namely, [Ln210Al140(μ2-OH)210(μ3-OH)540(OAc)180(H2O)156](ClO4)120·(MeCN)x·(H2O)y, (Ln = Dy and x= 27, y= 300 for 1; Ln = Y and x= 28, y= 420 for 2). Remarkably, the 350 metal atoms in 1and 2display a Keplerate-type four-shell structure of truncated icosidodecahedron@dodecahedron@dodecahedron@icosidodecahedron. The diameter of the cationic cluster in 1is approximately 5.0 nm, with an inner cavity diameter of about 2.8 nm and a window diameter of roughly 0.66 nm. The cluster in 1boasts an accessible inner void volume of up to 15,000 Å3. Notably, these cage clusters maintain stability in water, and the truncated icosidodecahedrons in 1and 2are the first of their kind synthesized to date. Given that the open hollow dodecahedral Ln–Al cage cluster has never been reported before, this work represents a member in the family of hollow open dodecahedral cages.

Adiabatic demagnetization refrigeration (ADR) is a promising cooling technology with high efficiency and exceptional stability in achieving ultralow temperatures, playing an indispensable role at the forefront of fundamental and applied science. However, a significant challenge for ADR is that existing magnetic refrigerants struggle to concurrently achieve low magnetic ordering temperatures (T0) and substantial magnetic entropy changes (−ΔSm) at ultralow temperatures. In this work, we propose the combination of Gd3+and Yb3+to effectively regulate both −ΔSmand T0in ultralow temperatures. Notably, the −ΔSmvalues for Gd0.1Yb0.9F3(1) and Gd0.3Yb0.7F3(2) in the 0.4–1.0 K range exceed those of all previously reported magnetic refrigerants within this temperature interval, positioning them as the most efficient magnetic refrigerants for the third stage to date. Although the −ΔSmvalues for Gd0.5Yb0.5F3(3) in 1–4 K are less than those of the leading magnetic refrigerant Gd(OH)F2, the −ΔSmvalues for Gd0.7Yb0.3F3(4) in 1–4 K at 2 T surpass those of all magnetic refrigerants previously documented within the same temperature range, making it the superior magnetic refrigerant for the fourth stage identified thus far.

Keggin-Fe13clusters are considered foundational building blocks or prenucleation precursors of ferrihydrite. Understanding the factors that influence the rotational configuration of these clusters, and their transformations in water, is vital for comprehending the formation mechanism of ferrihydrite. Here, we report syntheses and crystal structures of four lanthanide-iron-oxo clusters, namely, [Dy6Fe13(Gly)12(μ2–OH)6(μ3–OH)18(μ4–O)4(H2O)17]·13ClO4·19H2O (1), [Dy6Fe13(Gly)12(μ3–OH)24(μ4–O)4(H2O)18]·13ClO4·14H2O (2), [Pr8Fe34(Gly)24(μ3–OH)28(μ3–O)30(μ4–O)4(H2O)30]·6ClO4·20H2O (3), and [Pr6Fe13(Gly)12(μ3–OH)24(μ4–O)4(H2O)18]·13ClO4·22H2O (4, Gly = glycine). Single-crystal analyses reveal that 1has a β-Keggin-Fe13cluster, marking the first documented instance of such a cluster to date. Conversely, both 2and 4contain an α-Keggin-Fe13cluster, while 3is characterized by four hexavacant ε-Keggin-Fe13clusters. Magnetic property investigations of 1and 2show that 2exhibits ferromagnetic interactions, while 1exhibits antiferromagnetic interactions. An exploration of the synthetic conditions for 1and 2indicates that a higher pH promotes the formation of α-Keggin-Fe13clusters, while a lower pH favors β-Keggin-Fe13clusters. A detailed analysis of the transition from 3to 4emphasizes that lacunary Keggin-Fe13clusters can morph into Keggin-Fe13clusters with a decrease in pH, accompanied by a significant change in their rotational configuration.

Adiabatic demagnetization refrigeration is known to be the only cryogenic refrigeration technology that can achieve ultralow temperatures (≪1 K) at gravity-free conditions. The key indexes to evaluate the performance of magnetic refrigerants are their magnetic entropy changes (−ΔSm) and magnetic ordering temperature (T0). Although, based on the factors affecting the −ΔSmof magnetic refrigerants, one has been able to judge if a magnetic refrigerant has a large −ΔSm, how to accurately predict their T0remains a huge challenge due to the fact that the T0of magnetic refrigerants is related to not only magnetic exchange but also single-ion anisotropy and magnetic dipole interaction. Here, we, taking GdCO3F (1), Gd(HCOO)F2, Gd2(SO4)3·8H2O, GdF3, Gd(HCOO)3and Gd(OH)3as examples, demonstrate that the T0of magnetic refrigerants with very weak magnetic interactions and small anisotropy can be accurately predicted by integrating mean-field approximation with quantum Monte Carlo simulations, providing an effective method for predicting the T0of ultralow-temperature magnetic refrigerants. Thus, the present work lays a solid foundation for the rational design and preparation of ultralow-temperature magnetic refrigerants in the future.

A series of chiral heterometallic Ln–Co clusters, denoted as Co2Lnand Co3Ln2(Ln = Dy and Er), were synthesized by reacting the chiral chelating ligand (R/S)-2-(1-hydroxyethyl)pyridine (Hmpm), CoAc2·4H2O, and Ln(NO3)3·6H2O. Co2Lnand Co3Ln2exhibit perfect mirror images in circular dichroism within the 320–700 nm range. Notably, the Co2Erand Co3Er2clusters display pronounced magnetic circular dichroism (MCD) responses of the hypersensitive f–f transitions 4I15/2–4G11/2at 375 nm and 4I15/2–2H11/2at 520 nm of ErIIIions. This study highlights the strong magneto-optical activity associated with hypersensitive f–f transitions in chiral 3d–4f magnetic clusters.