A f a m i l y o f n a n o c l u s t e r s , [Ln 33 (EDTA) 12 (OAc) 2 (CO 3 ) 4 (μ 3 -OH) 36 (μ 5 -OH) 4 (H70 for 3; H 4 EDTA = ethylene diamine tetraacetic acid), was prepared through the assembly of repeating subunits under the action of an anion template. The analysis of the structures showed that compounds 1 and 2 containing 33 Ln 3+ ions were isostructural, which were constructed by three kinds of subunits in the presence of CO 3 2− as an anion template, while compound 3 had a slightly different structure. Compound 3 containing 32 Gd 3+ ions was formed by three types of subunits in the presence of CO 3 2− and C 2 O 4 2− as a mixed anion template. The CO 3 2− anions came from the slow fixation of CO 2 in the air. Meanwhile, one kind of high-nuclearity lanthanide clusters showed high chemical stability. The quantum Monte Carlo (QMC) calculation suggested that weak antiferromagnetic interactions were dominant between Gd 3+ ions in 3. Magnetocaloric studies showed that compound 3 had a large entropy change of 43.0 J kg −1 K −1 at 2 K and 7 T. Surprisingly, compound 2 showed excellent recognition and detection effects for permanganate in aqueous solvents based on the fluorescence quenching phenomenon.

Two series of cluster-based Ln-metal–organic frameworks (MOFs) with formulas {[Na@Ln8(EDTA)6­(H2O)22]­·ClO4·xH2O} n (x ≈ 28, Ln = Gd for 1, Ln = Eu for 2) and {[Na@Ln9(EDTA)6­(H2O)27]­·(ClO4)4·xH2O} n (x ≈ 26, Ln = Gd for 3, Ln = Eu for 4) were prepared by ethylene diamine tetraacetic acid (H4EDTA) to control the hydrolysis of lanthanide ions to form cluster-based secondary building blocks and hydrated metal ions as linkers. Structural analysis showed that all four compounds were formed by using {Na@Ln6} as the node and hydrated [Ln­(H2O)5]3+ ion as the linker. Compounds 1–2 and 3–4 featured a two-dimensional (2D) layered structure and a three-dimensional (3D) frame structure, respectively. Magnetic studies showed that compounds 1 and 3 displayed a considerable magnetocaloric effect with magnetic entropy values of 32.8 and 33.3 J kg–1 K–1, respectively, at low temperature and high field. The magnetic entropy changes of 3 did not increase greatly with the increase of the dimension due to the similar weak magnetic interactions and similar magnetic densities of compounds 1 and 3. Luminescence studies showed that compounds 2 and 4 had a good recognition effect on the cyclohexane molecule, and 4 displayed excellent sensitive sensing and a detection effect on Fe3+ ions in methanol based on the high-sensitivity fluorescence quenching phenomenon.

Three pairs of chiral Ln-Ag(I) clusters D/L-Ln 3 Ag 5 with C 3 symmetry were prepared by D/L-penicillamine as multidentate ligand bridged Ln 3+ and Ag(I) ions. The chiral ligand induced the molecular cluster to be chiral, and the CD spectra of the chiral compounds D/L-Ln 3 Ag 5 were slightly blue-shifted due to the lanthanide contraction. The studies of optical properties indicated that tunable photoluminescence from {AgS}-to-Ln 3+ was achieved by introducing Ln 3+ ions with different emission bands or regulating various excitation light.

A series of neutral lanthanide metal–organic frameworks (Ln-MOFs) with the formulas {[Ln4(L)3.5(μ3-OH)3(μ4-O)­(H2O)2]·H2O} n (Ln = Sm for 1, Ln = Eu for 2, Ln = Gd for 3, H2L = 2,5-pyrazine dicarboxylic acid) were prepared by using the multicarboxylic acid 2,5-pyrazine dicarboxylic acid to control the hydrolysis of Ln3+ ions. The coordination sites of Ln3+ ions were partially occupied by L2–, leaving only a limited number of sites available for aqua coordination, which inhibited the further hydrolysis of Ln3+ ions to form the precipitates of lanthanide oxides/hydroxides. Finally, the three-dimensional metal frameworks of compounds 1–3 were formed by {Ln4O4} as secondary building units (SBUs) and organic ligand L2– as linkers. These three compounds showed high stability, and especially compound 2 exhibited high chemically stability. The solid-state fluorescence emission spectra showed that compound 2 exhibited the red characteristic emission of Eu3+ ions. The studies of the luminescence recognition of different organic solvents indicated that compound 2 had an obvious fluorescence recognition effect on n-hexane featuring luminescent quenching. Meanwhile, compound 2 showed a sensitive detection effect and good cyclic effect on CrO4 2– in water solution, suggesting that compound 2 might be used as a highly stable and sensitive fluorescent probe for CrO4 2– ions in aqueous medium. Besides, magnetic studies showed that compound 3 had large magnetocaloric effects with a −ΔS m value of 42.4 J kg–1 K–1 at 2 K and 7 T, which might be a potential cryogenic magnetic cooler.

The intermetallic magnetic interaction is a key role for exploring magneto-structure relationship. Herein, a series of Mn-based clusters featuring metallacrowns with the formulas [MnIIMn4 III(L1)4(HL2)2(DMF)6]·4MeOH·3H2O (1), [GdMn4 III(L1)4(OAc)4]·H4TEA·2MeOH·H2O (2), [Gd4Mn4 III­(L1)4(HL2)2­(H2L1)4(OAc)4­(μ3-OH)2(DMF)2­(H2O)2]·4DMF·H2O·16MeOH·H3TEA (3), and [Gd6Mn4 III­Mn2 IV(L1)10(HL1)2­(H2L1)4(DMF)4­(H2O)4(MeOH)4]·4DMF·2MeOH·6H2O (4) (H3L1 = salicylhydroxamic acid, H2L2 = salicylic acid, MeOH = methanol, DMF = N,N-dimethylformamide, and H3TEA = triethylamine) were prepared using salicylhydroxamic acid as organic ligands. The structures of compounds 1–2, 3, and 4 featured 12-metallacrown-4, 16-metallacrown-6, and 28-metallacrown-10, respectively. Magnetic calculations showed that the obvious antiferromagnetic couplings of compounds 1–2 were mainly derived from MnIII···MnIII. For compound 3, the weak ferromagnetic couplings of GdIII···MnIII and MnIII···MnIII bridged through [M–O–N–M] manner were smaller than the antiferromagnetic couplings of GdIII···GdIII and GdIII···MnIII bridged by O atoms, resulting in the overall antiferromagnetic behavior. In compound 4, the weak ferromagnetic couplings of GdIII···MnIII/MnIII···MnIII/GdIII···MnIV/MnIII···MnIV bridged by the way of [M–O–N–M] were dominant. The abovementioned results revealed that the arrangement of metal ions displaying [M–N–O–M] is more likely to produce weak ferromagnetic coupling between metal ions, which is beneficial to the magnetocaloric effect (MCE). Meanwhile, compounds 3–4 showed considerable MCEs with a magnetic entropy change (−ΔS m) of 13.86 J kg–1 K–1 at 3.5 K, 7 T and 16.05 J kg–1 K–1 at 3 K, 7 T, respectively.