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Two Dy4 complexes, namely, [Dy4(L1)4(NO3)2(μ3-OH)2]·2C2H5OH·3H2O (1) and [Dy4(L2)4(NO3)2(μ3-OH)2]·3C2H5OH·8H2O (2), were successfully designed and synthesized under solvothermal conditions. X-ray d...

A superb alkali-resistant single-molecule-magnet (SMM) material with the molecular formula [Dy2Ni4(L)8(CH3COO)4(NO3)2] (1) (HL = 8-hydroxyquinoline) has been structurally and magnetically characterized. Single-crystal X-ray diffraction revealed that 1 possesses a hexanuclear [DyIII2NiII4] cluster, which is built by two triangular [DyIIINiII2] cores double-bridged through two CH3COO- ions. Interestingly, 1 can keep its original structure in dilute acid and common basic solutions (e.g., triethylamine and NaOH). More importantly, 1 is still stable after treatment with a 20 M NaOH aqueous solution for 1 month at room temperature. Magnetic measurements uncovered that 1 is an SMM under zero applied field with Ueff = 7.43 K. To the best of our knowledge, 1 is the first example of a 3d-4f SMM with such extreme alkali resistance. This work will broaden the vision of preparing SMM materials with excellent chemical stability.

The aggregation and formation of heterometallic nanoclusters usually involves a variety of complex self-assembly processes; thus, the exploration of their assembly mechanisms through process tracking is more challenging than that for homometallic nanoclusters. We explored here the effect of solvent on the formation of heterometallic clusters, which gave two heterometallic nanoclusters, [Dy2Co8(μ3-OCH3)2(L)4(HL)2(OAc)2(NO3)2(CH3CN)2]·CH3CN·H2O (1) and [Dy4Co6(L)4(HL)2(OAc)6(OCH2CH2OH)2(HOCH2CH2OH)(H2O)]·9CH3CN (2), with the H3L ligand formed from the in situ condensation reaction of 3-amino-1,2-propanediol with 2-hydroxy-1-naphthaldehyde in the presence of Co(OAc)2·4H2O and Dy(NO)3·6H2O. It is worth noting that the skeleton of cluster 1 has a high stability under high-resolution electrospray ionization mass spectrometry (HRESI-MS) conditions with a gradually increasing energy of the ion source. Cluster 2 underwent a multistep fragmentation even under a zero ion-source voltage for the measurement of HRESI-MS. Further analysis showed that cluster 2 underwent a possible fragmentation mechanism of Dy4Co6L6 → Dy2Co6L5/DyL → DyCo2L3/DyCo2L → DyL/Co2L2. Most notably, the species emerging in the formation process of cluster 1 were tracked using time-dependent HRESI-MS, from which we proposed its possible formation mechanism of H2L → Co2L2 → Co2DyL2/Co3L2 → Co3DyL2 → Co4DyL2 → Co5Dy2L4 → Co8Dy2L6. As far as we know, it is the first time to track the formation process of Dy-Co heterometallic clusters through HRESI-MS with the proposed assembly mechanism. The magnetic properties of the two titled DyIIIxCoII10-x (x = 2, 4) clusters were studied. Both of them exhibit slow magnetic relaxation, and 1 is a single-molecule magnet at zero direct-current field.

Two new [Dy4]-based coordination clusters [Dy4(L1)2(L2)4(NO3)2(EtOH)4]·2MeOH (1) (H3L1 = 2-(β-naphthalideneamino)-2-(hydroxylmethyl)-1-propanol, HL2 = 2-hydroxy-1-naphthaldehyde) and [Dy4(μ4-O)(HL3)4(H2L3)2]·3H2O·EtOH·CH3CN (2) (H3L3 = 3-(((2-hydroxynaphthaen-1-yl)methylene)amino)-propane-1,2-diol) with planar and butterfly-like skeletons, respectively, were synthesized and characterized. This revealed that 1 is a field-induced single-molecule magnet with an effective barrier of Ueff = 6.1 K under a dc field of 800 Oe and 2 shows slow magnetic relaxation behaviour with Ueff = 2.6 K under zero dc field. The magnetic dilution method was applied to further investigate the magnetic relaxation behaviors of 1 and 2; as a result, slow magnetic relaxation behaviors of 1 and 2 were mostly attributed to the single Dy3+ ions, which was also confirmed by the result of ab initio calculation. Interestingly, both of them possess excellent stability in water and common organic solvents, as well as in acid and base solutions with a wide pH range (2.5–14). Surprisingly, 2 is stable even in 18 M NaOH aqueous solutions, which is rarely reported in 0D coordination compounds and is a breakthrough for paramagnetic metal clusters in stability. It helps to develop chemically stable single-molecule magnets for their application in moisture and acidic/alkaline media.

Although the design and synthesis of high-nuclear lanthanide clusters with specific shapes and functions have been an active area of research, effective experience and rules to guide further systematic expansion of lanthanide clusters with different connections are lacking. Herein, we adjusted the steric hindrance effects on the substituents of diacylhydrazone ligands (H4L1, N′2,N′9-bis((E)-2-hydroxybenzylidene)-1,10-phenanthroline-2,9-dicarbohydrazide; H4L2, N′2,N′9-bis((E)-2-hydroxy-3-methylbenzylidene)-1,10-phenanthroline-2,9-dicarbohydrazide; H4L3, N′2,N′9-bis((E)-3-(tert-butyl)-2-hydroxybenzylidene)-1,10-phenanthroline-2,9-dicarbohydrazide) and reacted them with Dy(NO3)3·6H2O under solvothermal conditions to obtain three dysprosium clusters (1–3) with different shapes. The molecular formulas of the abovementioned clusters are [Dy16(L1)3(μ3-OH)25(NO3)11(H2O)10]·4CH3CN·8CH3OH, [Dy10(L2)4(μ2-OH)2(μ3-O)4(NO3)4(CH3CN)2(CH3OH)4(H2O)8]·CH3OH·8H2O, and [Dy5(L3)2(μ2-CH3O)(μ2-OH)2(μ4-O)(NO3)2(CH3OH)2]·6CH3OH·2CH3CN. Cluster 1 with a brucite-like planar structure crystallizes in the P21/n space group of the monoclinic system. The Dy(III) ions in the cluster 1 structure are bridged by μ3-OH− to form a plane triangle shape. In addition, the structure of cluster 1 contains three layers of Dy(III) ions (1 + 6 + 9) with different coordination environments. Cluster 2 crystallizes in the P space group of the triclinic system. The cluster core in cluster 2 is composed of two molecules of missing cubane Dy4O6 and two Dy(III) ions. The ligand (L2)4− adopts two coordination modes (μ3-η1:η1:η2:η1:η1:η2:η1:η1 and μ5-η2:η1:η1:η1:η1:η1:η1:η1:η1:η2) to chelate Dy(III) ions. In addition, Dy(III) ions in Dy4O6 are connected by μ2-OH− and μ3-OH−. Two molecules of planar Dy3L3 intersect to form cluster 3, and it crystallizes in the I2/a space group of the monoclinic system. The analysis of the structure of clusters 1–3 shows that they are formed by a stepwise assembly process from outside to inside. To the best of our knowledge, a very small number of examples have reported that a series of differently connected dysprosium clusters were obtained through the regulation of substitution effects. Notably, we are the first to propose the out-to-in growth mechanism of planar high-nucleus dysprosium clusters. The results of the variable temperature AC susceptibility test show that clusters 1, 2, and 3 exhibit single-molecule magnet-like behavior under zero-field conditions.

Using the pyridine–triazole based ligand of bis(3-(pyridin-2-yl)-1,2,4-triazol-5-yl)methane (H2L), two hexanuclear dysprosium(III) complexes, [Dy6(μ4-NO3)2 (OAc)6(L)4(DMF)2]·2NO3 (1) and [Dy6(μ3-OH)4(μ2-OH)2(OAc)4(L)4(EtOH)4]·2H2O (2), have been successfully obtained by hydrothermal reaction in different solvents. The crystal structure analysis reveals that the {Dy6} core in 1 is connected by two μ4-NO3− ions, whereas by four μ3-OH− and two μ2-OH− ions in 2. The HRESI-MS (high-resolution electrospray ionization mass spectrum) measurement of 1–2 was recorded. The presence of prominent peaks for the {Dy6} fragment in 1 (m/z, 1354–1380) at different ion-source voltages showed the higher solution stability and structural integrity of the {Dy6} cluster in 1, compared with that in 2. Temperature- and frequency-dependent alternating current (AC) susceptibility measurements of 1–2 in a zero direct current field display only a characteristic feature of single-molecule magnet (SMM) behavior for 2, indicating different magnetic behavior.

The formation of heterometallic clusters usually involves a much more complex self-assembly process than that of homometallic clusters. Thus the tracking of their assembly mechanism is challenging. To achieve this task, we designed one OH-containing Schiff base ligand of 1-[[(2-hydroxyethyl)imino]methyl]-2-naphthalenol (H2L) with coordination pockets facile for selective coordination with CoII/NiII and 4f metal ions. Its reactions with the corresponding metal ions gave two new isostructural dodecanuclear complexes [Dy4Co8(μ3-OH)8(L)8(OAc)4(H2O)4]·3EtOH·3CH3CN·H2O (1) and [Dy4Ni8(μ3-OH)8(L)8(OAc)4(H2O)4]·3.5EtOH·0.5CH3CN·5H2O (2), which feature a vertex-sharing tetracubane cyclic skeleton with the four DyIII ions wrapped by the eight 3d metal ions. High-resolution electrospray mass spectrometry (HRESI-MS) tests showed that the skeletons of clusters 1 and 2 have high stability even under gradually increasing energy of the ion source. Most notably, the intermediates formed in the reaction courses for clusters 1 and 2 were tracked using time-dependent HRESI-MS, which gave different proposed assembly mechanisms for 1 (H2L → DyL → DyCoL → Dy2CoL → Dy3CoL → Dy4CoL2 → Dy4Co2L3 → Dy4Co4L4 → Dy4Co8L8) and 2 (H2L → NiL → Dy2NiL2 → Dy3NiL2 → Dy4NiL2 → Dy4Ni2L3 → Dy4Ni4L3 → Dy4Ni6L4 → Dy4Ni8L8), respectively. This is the first time that different assembly mechanisms for isostructural heterometallic complexes are shown. Detailed magnetic studies revealed the absence of slow magnetic relaxation for 1 and the presence of slow magnetic relaxation for 2 with an energy barrier of 7.66 K and a pre-exponential factor of 1.45 × 10−6 s. The different magnetic performances of the two title complexes might be caused by the different metal ions of Co(II) and Ni(II).

Employing tripodal Schiff base ligand of tris[4-(2-hydroxy-3-methoxyphenyl)-3-aza-3-butenyl]amine (H3L1) and auxiliary ligand of 2-hydroxy-5-chlorobenzaldehyde, a 3d–4f cluster of $$\left[ {{\text{Dy}}^{{{\text{III}}}} {{{\text{Mn}}}}_{ 2}^{{{\text{II}}}} \left( {{{\text{L}}}^{ 2} } \right)_{ 2} } \right]\left[ {{{\text{NO}}}_{ 3} } \right] \cdot 5 {{{\text{CH}}}}_{ 3} {{{\text{OH}}}}$$ (1) was synthesized. Intriguingly, the H3L1 ligand has transformed into another Schiff base ligand of {N-[4-(2-hydroxy-5-chlorophenyl)-3-aza-3-butenyl]-N′,N′′-bis[4-(2-hydroxy-3-methoxyphenyl)-3-aza-3-butenyl]}amine (H3L2) in situ during the coordination process, that one of terminal groups of H3L1 ligand was substituted. A pair of such (L2)3− ligands chelate a DyIII and two MnII ions to form a quasi-liner {MnIIDyIIIMnII} skeleton of 1, in which the adjacent MnII and DyIII ions were bridged by three Ophenol. To the best of our knowledge, this in situ substitution of the terminal group of Schiff base ligand has not been reported in previous literature. DC magnetic susceptibility measurements were conducted on 1, revealing the weak antiferromagnetic interactions between the DyIII and MnII centers. A quasi-liner a {MnIIDyIIIMnII} cluster has been constructed from tripodal Schiff base ligand of H3L1. The H3L1 ligands underwent an in situ substitution in the coordination, which has been not reported in previous literature so far as we known. Magnetic studies reveal the weak antiferromagnetic interactions between DyIII and MnII ions.

Herein we report a variety of supramolecular architectures that are self-assembled by the highly charged anionic Ti4L6 (L = embonate) cages and noble-metal Ag+ ions in the presence of the different ligands, including six Ti4L6-Ag(PPh3) cages in whose structures the Ti4L6 cage catches various in situ formed [Ag(PPh3)]+ moieties by a coordination bond and one cocrystal superstructure of a Ti4L6 cage with an in situ generated [Ag2(Ph2P(CH2)5PPh2)3]2+ cage via supramolecular interactions. In addition, the third-order nonlinear-optical properties of these compounds are investigated in detail.

The reaction of a multidentate diacylhydrazine ligand N,N′-bis(2-hydroxy-3-naphthoyl)oxalylhydrazide (H6hnohz) with copper acetate in the presence of pyridine (Py), resulted in a novel Cu nanocluster, [Cu 9 II (hnohz)3(Py)8]·7DMSO (1). This nanocluster consists of a {CuII4} and a {CuII5} cluster units, which were linked together by the coordination bonds between them owing to the Jahn–Teller effects of the CuII centers and flexible coordination modes of the hnohz6− ligands. The Py was found to act as not only the deprotonating reagent in the synthesis, but the peripheral ligand in molecular structure. Whether in {CuII4} or in {CuII5} unit, the CuII ions are approximatively coplanar. And the meaning planes of two units are just parallel. Thus 1 displays a double-layered cage-like skeleton that was rarely reported in previous literature. Variable temperature magnetic susceptibility measurement revealed dominate antiferromagnetic couplings between the CuII ions in the system of 1.

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.

The novel multidentate chelating ligands N′-(2-pyridylmethylidene)-2-(2-pyridylmethylideneamino)benzohydrazide (Hpphz) and N′-(2-salicylmethylidene)-2-(2-salicylmethylideneamino)benzohydrazide (H3sshz), which incorporate both amine and acylhydrazine Schiff base groups, were synthesized and investigated in DyIII coordination chemistry. The reactions of Hpphz and Dy(OAc)3·4H2O have yielded two {Dy2} featuring double OAc− bridges: [Dy2(H2aphz)2(OAc)4(ROH)2] [R = Me (1) and Et (2)], where the Hpphz ligands were in situ hydrolyzed into 2-amino-(2-pyridylmethylideneamino)benzohydrazide ions (H2aphz−). Besides, the reaction between H3sshz and Dy(NO)3·6H2O afforded a [Dy6(sshz)4(μ3-OH)4(μ4-O)(MeOH)4]2·17.5MeOH·2H2O cluster (3). This cluster contained two discrete {Dy6} cores, each of which consisted of a pair of {Dy3} triangular units. All the complexes displayed a single relaxation process of single-molecule magnet (SMM) behaviors under a zero dc field. Both 1 and 2 showed field-induced dual magnetic-relaxation behaviors. However, their diluted samples (1@Y and 2@Y) only showed one-step relaxation behaviors whether under a zero or applied dc field, indicating that the dual magnetic-relaxation behaviors of 1 and 2 were absent after the dilution. Combined with ab initio calculations, it could be infered that the dual magnetic-relaxation behaviors of 1 and 2 might be ascribled to the joint contributions of the single ion anisotropy and magnetic interactions. Examples of this type are rather rare in previous studies. Ab initio calculations also suggested that the discrepancy between the relaxation processes of 1 and 2 may be caused by the small difference between their magnetic interactions.

A novel discrete {Co14Mo24} nanoscale cluster, {CoIII2CoII10Cl2(dpbt)3(H2O)2[CoIIMoV12O31(CH3O)9]2}·24CH3OH (1) (here, dpbt = 5,5′-di(pyridin-2-yl)-3,3′-bi(1,2,4-triazole)), with a triangular Co4 core encapsulated in two novel capped Co-substituted Keggin-type Co5Mo12O40 anions, has been isolated from alkaline methanol solution. The high-resolution electrospray ionization mass spectrum (HRESI-MS) of microcrystalline 1 in MeOH/CH2Cl2 (v : v = 2 : 1) was recorded. Two prominent overlapping peaks in the range of m/z = 2740–2840 and 1820–1880 for the discrete fragments of [CoIII2CoII12MoV24O62Cl2(dpbt)3(H2O)2(CH3O)x(OH)18−x-2H]2− (x = 9–18, F1) and [CoIII2CoII12MoV24O62Cl2(dpbt)3(H2O)2(CH3O)x(OH)19−x-2H]3− (x = 6–13, F2), respectively, are obtained, confirming the {Co14Mo24} composition in 1. In addition, weak anti-ferromagnetic interactions in 1 are observed.

Two novel {Dy2}-based one dimensional chain compounds {[Dy2(H3L)4(OAc)6]·2MeOH}n (1) and {[Dy2(H3L)4(OAc)4(NCS)2]·2MeOH}n (2) (H3L = 1,3-bis(2-hydroxynaphthalenemethyleneamino)-propan-2-ol) have been prepared under solvothermal conditions. Crystal structure analyses indicate that 1 and 2 feature similar 1D chain structures bearing dinuclear secondary building units. The difference between these two structures is that one chelated acetate ligand of Dy(III) ion in 1 is replaced by one monodentate coordinated NCS− ion in 2, leading to their different coordination numbers and geometry configurations to Dy(III) ion. Magnetic properties indicate that 1 and 2 display slow magnetic relaxation behavior with an effective energy barrier of 16.44(2) K in 1 and 8.02(2) K in 2, respectively, which is maybe attributed to the subtle crystal field perturbation of Dy(III) ions.

The solvent-induced topological and structural diversities of two Co(II) complexes, namely, [Co(L)2(SCN)2] (Co1) and [Co2(L)2(SCN)(OAc)3] (Co2) (L = 8-methoxyquinoline), were comparatively analyzed. Certain proportions of L, Co(OAc)2·4H2O, and NaSCN were mixed and dissolved in CH3OH at 60 °C to obtain complex Co1. Complex Co2, an asymmetric dinuclear compound, was obtained by simply replacing CH3OH with CH3CN as the solvent. The Co(II) ion in complex Co1 was coordinated by the N4O2 mode provided by two L ligands and two SCN– anions. The two Co(II) ions in Co2 were in the N2O4 and NO5 coordination environment and were linked by two μ2-OAc– bridges and one rare μ3-OAc– bridge. Weak interaction analysis revealed that complexes Co1 and Co2 exhibited 6-connected shp and 14-connected fcu nets, respectively. Magnetic studies showed that Co1 demonstrated single-ion magnet behavior under 2000 Oe. These behaviors are indicative of clearly field-induced single-ion magnetic behavior with Ueff = 34.7(2) K and τ0 = 2.7(2) × 10–7 s under 2000 Oe dc field, respectively. By contrast, Co2 lacked frequency dependence under zero-field conditions. Electrospray ionization mass spectrometry indicated that two complexes were stable in N,N-dimethylformamide.

Specially shaped high-nuclear lanthanide cluster assembly has attracted widespread attention, but the study of their self-assembly mechanism is still stagnant. Herein, we used a polydentate chelating bis-acylhydrazone ligand to construct a rare 16-nuclear dysprosium cluster 1 with a brucite-like structure. The capture agents, pivalic acid and di(pyridin-2-yl)methanone, were added into the reaction system, and the hexanuclear dysprosium cluster 2 and heptanuclear dysprosium cluster 3 were obtained, respectively. Clusters 2 and 3 support the out-to-in growth mechanism as key evidence. To the best of our knowledge, this study is the first to use truncation reaction to decipher the formation mechanism of high-nuclear lanthanide clusters.

The serialized expansion of high-nuclear clusters usually includes the controlled variable method and changes only a single variable. However, changing both variables will greatly increase the complexity of the reaction simultaneously. Therefore, the use of a two-component regulation reaction is rare. Herein, we used a diacylhydrazone ligand (H4L1) with multidentate chelating coordination sites for the reaction with Gd(NO3)3·6H2O under solvothermal conditions to obtain an example of 16-nucleus disc-shaped cluster 1 with a brucite structure. The overall structure of cluster 1 can be regarded as an equilateral triangle, which is formed by three (L1)4- ions that can be regarded as "sides" and wrap the four-layer metal center Gd(III) ions. Notably, upon simultaneous regulation of the substituent of the ligand and the coordination anion, heptanuclear gadolinium cluster 2 was obtained. Cluster 2 can be regarded as a butterfly structure, which was formed by connecting two Gd3L2 molecules that were not in the same plane and through the central Gd(III) ion as an intersection. Moreover, hexanuclear gadolinium cluster 3 was obtained by changing the ligand substituent and adding an auxiliary ligand. Cluster 3 can be regarded as a chair structure, which was composed of two molecules of diacylhydrazone ligand (L2)4- wrapping vacant cubane shared by four vertices. This study was the first to construct a series of high-nuclear gadolinium clusters through two-component regulation manipulation. The study of the magnetocaloric effect showed that the maximum values of -ΔSm for clusters 1-3 were 34.05, 29.04, and 24.32 J kg-1 K-1, respectively, when T = 2 K and ΔH = 7 T.

Metal nanoclusters have a certain rigidity due to their specific coordination patterns and shapes; thus, they face extreme difficulty in folding into a specific direction to form a double-helix structure and in further interconnecting to form metal-helix frameworks (MHFs). To date, no MHFs have been produced by the formation of heterometallic clusters. Selecting the appropriate "bonding molecules" to bond metal nanoclusters in a specific multiple direction is one of the most effective strategies for designing synthetic MHFs. In this study, we realized for the first time the control of different orientations of μ3 -NO3- to join heterometallic clusters (Cu10 Dy2 ) and subsequently form a left-handed double helix chain, which further joins to form MHFs. In the structure of the MHFs, four different directions of bridging μ3 -NO3- exist, three of which are involved in the linkage of the double-helix chain. Each μ3 -NO3- is connected to three adjacent Cu10 Dy2 . Herein, we extend a new method for designing synthetic double-helix structures and MHFs, thereby further laying the foundation for the development of similar DNA double-helix structures and nucleic acid secondary structures in vitro.

The assembly process of lanthanide clusters often involves various complex assembly methods. Hence, studying the stepwise assembly mechanism is extremely difficult. In the assembly process of lanthanide clusters, if the in situ reaction or competitive reaction is involved, the reaction intermediates undergo rapid and complex changes, which makes research on the assembly mechanism even more difficult. Herein, 1-methyl-1H-benzo[d]imidazole-2-carbaldehyde (La) and 1-aminonaphthalen-2-ol (Lb) undergo a stepwise assembly reaction with Dy(III) salts under the promotion of a in situ Schiff base reaction to achieve Dy2 synthesis. The stepwise assembly mechanism is La + Lb → HL1 → Dy1 → Dy2. In the above Dy2 formation reaction, La is changed to 2-hydroxy-3-methoxybenzaldehyde (Lc), and then pyridin-2-ylmethanamine (Ld) is added. We have found that two different Schiff base ligands are formed in situ, and both are coordinated with Dy(III) ions to form a mixed ligand cluster Dy4 by competitive and stepwise assembly....

A novel Fe(III) cluster formulated as [ $${\text{Fe}}^{\text{III}}_{8}$$ (schhz)4(Py)6(H2O)2]∙2H2O (1) was synthesized by the hydrothermal reaction of FeCl2 and a symmetrical diacylhydrazine ligand N,N′-bissalicyl-1,3-cyclohexanedicarbohydrazide (H6schhz) in the presence of pyridine (Py) and pyrazine (Pz). It displays a nano-sized [24-MC-8] azametallacrown (azaMC) structure that eight Fe(III) ions are linked together by N–N bridges from four schhz6− ligands. To the best of our knowledge, it is the second case of Fe(III) [24-MC-8] azaMC up to now. The magnetic investigations reveal that the N–N bridges convey antiferromagnetic couplings between the Fe(III) centers in the system.

Two mononuclear dysprosium complexes (Et3NH)[Dy(BrMQ)4]·H2O·DMF(BrMQ-Dy) and (Et3NH)[Dy(ClMQ)4]·H2O·DMF (ClMQ-Dy) (H-BrMQ = 5,7-dibromo-2-methyl-8-quinolinol, H-ClMQ = 5,7-dichloro-2-methyl-8-quinolinol) were synthesized and characterized. The Dy(III) ions in complexes BrMQ-Dy and ClMQ-Dy have a pseudo-D4d local symmetry. Magnetic characterizations reveal that complex BrMQ-Dy is a single-ion magnet and complex ClMQ-Dy exhibits field-induced slow magnetic relaxation behaviors. The calculated effective barriers of BrMQ-Dy, BrMQ-Dya, ClMQ-Dy, and ClMQ-Dya are 47.8, 27.3, 96.0, and 65.5 cm-1, respectively (BrMQ-Dya and ClMQ-Dya represent the desolvated samples of BrMQ-Dy and ClMQ-Dy, respectively). Ab initio calculations confirmed that coordination symmetry of the Dy(III) ions, electron-withdrawing ligands, and the guest molecules is a key factor affecting the magnetic dynamics of the two complexes. The IC50 values of BrMQ-Dy and ClMQ-Dy against BEL-7404, HeLa, and Hep-G2 cancer cells were 1.01-22.06 μM. Interestingly, two Dy(III) complexes were less toxic to normal HL-7702 cells. BrMQ-Dy and ClMQ-Dy significantly induced cell arrest at G2 phase and down-regulated the G2 phase-related protein levels. Various experiments suggested that BrMQ-Dy and ClMQ-Dy also caused dysfunction of mitochondrial pathways in HeLa cells. Taken together, the different in vitro anticancer activity of complexes BrMQ-Dy and ClMQ-Dy in the order of 5,7-dichloro substitution > 5,7-dibromo substitution.

To develop new lanthanide single-molecule magnets (SMMs), two new complexes of [Dy2(MeOH)2(HL1)2(NO3)2]·2MeOH (1) and [Dy6(μ3-OH)2(L2)2(HL2)2(H2L2)2Cl2(EtOH)2]Cl2·3EtOH·CH3CN (2) were obtained by reacting Dy(NO)3·6H2O with 3-amino-1,2-propanediol in the presence of 2-hydroxynaphthaldehyde for 1 and by reacting DyCl3·6H2O with 1,1-di(hydroxymethyl)ethylamine in the presence of 2-hydroxynaphthaldehyde for 2, respectively, in which the Schiff base ligands of 3-(((2-hydroxynaphthaen-1-yl)methylene)amino)-propane-1,2-diol (H3L1) and 2-(β-naphthalideneamino)-2-(hydroxylmethyl)-1-propanol (H3L2) were in situ formed. The two Dy(III) ions in 1 are linked by two Oalkoxy atoms of two (HL1)2- ligands to build a dinuclear skeleton. Complex 2 presents a nearly planar hexanuclear skeleton constructed from four edge-shared triangular Dy3 units with the two peripheral Dy3 units consolidated by two μ3-O bridges and the two central Dy3 units consolidated by one μ3-O bridge. Obviously, they exhibit a different topological arrangement resulting from the linkage of the Schiff base ligands. Both of them are typical SMMs under zero dc fields, with a Ueff/ kB value of 34 K for 1 and 40 K for 2, respectively. Multiple processes are involved in the relaxation processes of 1 and 2. The different SMM performances of the two titled complexes reveal a tuning effect of Schiff base ligands through tuning the coordination environments and topological arrangements of dysprosium(III) ions, which is supported by the theoretical calculations.

2-Hydroxy-3-methoxybenzaldehyde (L1), 3-amino-1,2-propanediol (L2), trimethylacetic acid (pivalate) and Ln(NO3)3·6H2O were reacted at 80 °C to obtain two hexanuclear clusters [Ln6(HL)2(μ3-OH)2(μ3-OCH3)2(C5H9O2)10(CH3OH)2]·X (Ln = Gd (1, X = 4CH3OH), Er (2)), respectively. The aldehyde group of ligand HL1 is coupled with the amino group of HL2 to obtain 2-(2,3-dihydroxpropyliminomethyl)6-methoxyphenol (H3L). The coordination mode adopted by ligand L3− is μ4-L-k8O1,O2:O2,N1,O3:O3:O3,O4. Trimethylacetic acid adopts three different coordination modes in the six-nuclear cluster. The metal center Ln1 is in the N1O8 coordination environment, and both Ln2 and Ln3 are in the O8 coordination environment. Each of the hexanuclear complex is constructed with Ln3 triangular motifs as building blocks, and the six Ln(III) ions are arranged in a chair-shaped conformation. In magnetization studies of 1 exhibited a large magnetocaloric effect of 20.0 J kg−1 K−1 at 4 K for ΔH = 5 T.

The discovery of hydrogen-bonded organic frameworks (HOFs) has offered new opportunities for the expansion of porous materials. The field of HOFs has also introduced a new challenge—the design and synthesis of lanthanide HOFs (Ln–HOFs). Given that Ln complexes have various coordination modes, complex coordination structures, and irregular shapes, Ln–HOFs are extremely difficult to construct. In this study, a series of dysprosium-based HOFs (Dy–HOFs), namely, [Dy(L1)3(CH3OH)·Phen]n (Cl-1) and [Dy(L2)3(CH3OH)·Phen]n (Br-1), were designed and synthesized for the first time under solvothermal conditions of 5,7-dichloro/dibromo-2-methyl-8-quinolinol (L1/L2), Dy(NO3)3·6H2O, and 2,9-dimethyl-1,10-phenanthroline (Phen). The porous Cl-1 (Br-1) was filled with Phen molecules linked by various supramolecular weak interactions. After Cl-1 (Br-1) was incubated at 260 °C for 2 h under a N2 atmosphere, we found that only free Phen in the pores disappeared and Cl-2 (Br-2) was obtained. Magnetic characterization studies revealed that Cl-1 and Br-1 exhibited inconspicuous slow relaxation behavior. Unexpectedly, Cl-2 and Br-2 exhibited an evident single-ion magnetic (SIM) behavior, and their energy barriers were 97 and 87 K, respectively. We achieved the off → on SIM conversion of the Dy–HOFs for the first time.

Three {Ln12} (Ln = Gd (1), Tb (2), Dy (3)) nanocalix clusters with a novel ligand of N,N′-bis(o-vanillidene)-1H-imidazole-4,5-dicarbohydrazide (H5ovih) were synthesized via the amine-templating strategy. The skeletal structures of these clusters were constructed from three symmetric {Ln4} units via the linkage of three V-type ligands, with a calix shape, which has not been reported previously. Complex 1 exhibited a clear magnetocaloric effect (MCE), whose maximum −ΔSm value reached 36.77 J kg−1 K−1 at 70 kOe and 2.0 K.

The formation of high-nuclearity clusters of lanthanide usually involves many complicated self-assembly processes. Thus, tracking the formation process is extremely difficult and research on the assembly mechanism is very rare. In this study, a Dy-exclusive nanocluster containing vertex-sharing [Dy4(μ3-OH)4] cubanes, denoted as [Dy12(L)8(OH)16(CH3O)8(H2O)8]·(CH3O)4 (Dy12, L = quinoline-2-carboxylate), was designed and synthesized from L and DyCl3·6H2O. Eight quinoline-2-carboxylate ligands were encapsulated on the periphery of the Dy12 cluster, which served to stabilize the core. The high stability of the Dy12 cluster core was further confirmed by high-resolution electrospray-ionization mass spectrometry (HRESI-MS). With increased ion-source energy, only CH3O− and OH− bridging ligands were replaced inside the Dy12 cluster. Notably, eight intermediate fragments were successfully observed from the Dy12 cluster formation by time-dependent HRESI-MS. First, ligand L captured Dy3+ to give Dy1, which further formed Dy2 through μ2-O bridging. The Dy12 cluster was constructed in one step with four Dy2 and four Dy3+ as templates: L → Dy1 → Dy2 → Dy12. Moreover, a series of Dy3–Dy6 fragment peaks with relatively weak intensities were observed, and an alternative stepwise-assembly route was proposed: L → Dy1 → Dy2 → Dy3 → Dy4 → Dy5 → Dy6 → Dy12. On comparing the two different assembly methods, the multitemplate guided assembly formed Dy12 was found to be dominant. To the best of our knowledge, this study was the first to propose the involvement of two self-assembly mechanisms in the construction of lanthanide clusters, as further confirmed by HRESI-MS. Magnetic studies further showed that Dy12 clusters exhibited field-induced single-molecule magnet behavior.

The reactions of dysprosium nitrate with the main ligand of tropolone (HL) in the presence of ancillary ligands of phenanthroline (phen) or 1,3,5-benzenetricarboxylic acid (H3BTC) gave three mononuclear complexes, [Dy(phen)2(L)(NO3)2] (1), [Dy(phen)(L)3]·H2O (2) and [Dy(H3BTC)(H2O)(L)3]2·3H2O (3). They present different sets of mixed ligands. The Dy(iii) ions are ten-coordinated to build a bicapped square anti-prismatic geometry for complex 1 and eight-coordinated in dodecahedral geometries for complexes 2 and 3. Their magnetic properties were investigated in detail. Complexes 1 and 2 are single ion magnets under an external field, and complex 3 is a single ion magnet under zero field. This revealed a tuning effect on the performances of single ion magnets from ancillary ligands. These experimental magnetic behaviours are supported by the results from ab initio calculations, including g-tensors, averaged transition magnetic moments, magnetic easy axes, and crystal field parameters.

Two mononuclear dysprosium(iii) complexes [Dy(H3NAP)2Cl2]Cl·EtOH (1) and [Dy(H3NAP)2(H2O)Cl2]Cl·-2CH3CN·MeOH·0.5H2O (2) were obtained by coordinating an in situ formed Schiff base ligand of 1,3-bis(2-hydroxynaphthalenemethyleneamino)-propan-2-ol (H3NAP) to the dysprosium(iii) ion. Their Dy(iii) centers are six and seven-coordinated in octahedral and pentagonal-bipyramidal coordination geometries, respectively. Their structural difference is caused by the additional coordinated water molecule in the equatorial positions of complex 2 in comparison with that of complex 1. The well designed semi-rigid ligand contributes significantly to the low coordination numbers of Dy(iii) ions in the two title complexes, as well as to their structural difference. Magnetic investigations revealed that complexes 1 and 2 are both field-induced single-ion magnets (SIMs) with their effective energy barriers being 22.9(6) and 153.9(5) K, respectively. They are typical SIM examples with their performances tuned by the coordination geometries of metal ions.

The most effective way to understand reaction mechanisms and kinetics is to identify the reaction intermediates and determine the possible reaction patterns. The influencing factors that must be considered in the self-assembly of clusters are the type of ligand, metal ion, coordination anion and the pH of the solution. However, changes in ligand substituents resulting in different self-assembly processes to obtain different types of structures are still very rare, especially with –H and –CH3 substituents, which do not exert significant steric hindrance effects. In this study, planar mononuclear Ni(L1)2 (L1 = 2-ethoxy-6-(iminomethyl)phenol) was dissolved in methanol and combined with Dy(NO3)3·6H2O for 48 h at room temperature to obtain a butterfly-like Ni2Dy2 cluster ([Dy2Ni2(L1)4(CH3O)2(NO3)4], 1). The Dy(III) ions in cluster 1 are in an O8N coordination environment, and the Ni(II) ions are in an O5N coordination environment. High-resolution electrospray ionization mass spectrometry (HRESI-MS) was used to track species changes during the formation of cluster 1. Six key intermediate fragments were screened, and the self-assembly mechanism was proposed as Ni(L1)2 → HL1 + NiL1 → DyL1/Ni(L1)2′ → DyNi(L1)2 → Dy2Ni2(L1)4. Through this assembly mechanism, we found that Ni(L1)2 was first cleaved into HL1 + NiL1 and then further assembled to obtain 1. Another butterfly-like tetranuclear heterometallic cluster ([Dy2Ni2(L2)4(CH3O)2(NO3)4], 2) was obtained using planar mononuclear Ni(L2)2 (L2 = (E)-2-ethoxy-6-((methylimino)methyl)phenol) with –CH3 substitution on the nitrogen atom under the same reaction conditions. The structural analysis of cluster 2 showed that the Dy(III) ions are in an O9 coordination environment, and the Ni(II) ions are in an O4N2 coordination environment. HRESI-MS was used to trace species changes during the formation of 2, and the assembly mechanism was proposed as Ni(L2)2 → DyNi(L2)2 → Dy2Ni(L2)2 → Dy2Ni2(L2)4. Analysis of the assembly mechanism of 2 showed that Ni(L2)2 was twisted during the reaction, and its coordination point was exposed to capture the Dy(III) ions. Finally, Dy(NO3)3·6H2O was replaced with NaN3 to obtain a [Ni2Na2(L2)4(N3)4] cluster (3) under the same reaction conditions and verify the above-mentioned torsion step. HRESI-MS was also used to trace the assembly process, and the assembly mechanism was proposed as Ni(L2)2 → NiNa(L2)2 → NiNa2(L2)2 → Ni2Na2(L2)4. Herein, the effect of interference from substitution and the regulation self-assembly process were discovered in the formation of 3d–4f heterometallic clusters, and different types of coordination clusters were obtained.

Resolving the structure–property relationships of two-dimensional (2D) organic–inorganic hybrid perovskites is essential for the development of photovoltaic and photoelectronic devices. Here, pressure (0–10 GPa) was applied to 2D hybrid perovskite flakes mechanically exfoliated from butylammonium lead halide single crystals, (C4H9NH3)2PbI4, from which we observed a series of changes of the strong excitonic emissions in the photoluminescence spectra. By correlating with in situ high-pressure X-ray diffraction results, we examine successfully the relationship between structural modifications in the inorganic PbI42– layer and their excitonic properties. During the transition between Pbca (1b) phase and Pbca (1a) phase at around 0.1 GPa, the decrease in ⟨Pb–I–Pb⟩ bond angle and increase in Pb–I bond length lead to an abrupt blue shift of the excitonic bandgap. The presence of the P21/a phase above 1.4 GPa increases the ⟨Pb–I–Pb⟩ bond angle and decreases the Pb–I bond length, leading to a deep red shift of the excitonic bandgap. The total band gap narrowing of ∼350 meV to 2.03 eV at 5.3 GPa before amorphization, facilitates (C4H9NH3)2PbI4 as a much better solar absorber. Moreover, phase transitions inevitably modify the carrier lifetime of (C4H9NH3)2PbI4, where an initial 150 ps at ambient phase is prolongated to 190 ps in the Pbca (1a) phase along with enhanced photoluminescence (PL), originating from pressure-induced strong radiative recombination of trapped excitons.The onset of P21/a phase shortens significantly the carrier lifetime to 53 ps along with a weak PL emission due to pressure-induced severe lattice distortion and amorphization. High-pressure study on (C4H9NH3)2PbI4 nm-thin flakes may provide insights into the mechanisms for synthetically designing novel 2D hybrid perovskite based photoelectronic devices and solar cells. Ministry of Education (MOE) Accepted version T.T.Y., J.X.Y., and Z.X.S, gratefully acknowledge the Ministry of Education (MOE) for the following grants: AcRF Tier 1 (Reference No: RG103/16); AcRF Tier 2 (MOE2015-T2-1- 148); AcRF Tier 3 (MOE2011-T3-1-005). J.X.Y. is supported by the National Natural Science Foundation of China (Grant No. 11704185) and the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20171021). T.C.S. receives funding from the Ministry of Education Academic Research Fund Tier 1 Grant RG173/16, Tier 2 Grants MOE2015-T2-2- 015 and MOE2016-T2-1-034, and from the Singapore (NRF) through the Singapore−Berkeley Research Initiative for Sustainable Energy (SinBeRISE) CREATE Program and the Competitive Research Program NRF-CRP14-2014-03. S.H.W. is supported by the National Key Basic Research Program of China (2016YFB0700700) and National Natural Science Foundation of China (51672023, 11634003, U1530401). S.J. and J.F. thank Dr. Zhongwu Wang and Dr. Ruipeng Li for their assistance and acknowledge the support from Custom Electronics Inc. and Binghamton University. CHESS was supported by the NSF award DMR-1332208.

A Cu coordiantion polymer, namely, [Cu3(ovph)(Py)2Cl2] (1) [H4ovph = N,N′-bis(o-vanillidene)pyridine-2,6-dicarbohydrazide]; Py = Pyridine], was synthesized by solvothermal reaction of copper acetate and diacylhydrazone ligand H4ovhp. It was characterized by element analysis, FT-IR, thermogravimetric analysis, PXRD and single crystal X-ray diffraction. Structural analysis indicated that the N–N bonds of its ovph4− ligands bridge the Cu2+ ions to form quasi-linear [Cu3] cluster-based units, which were further linked together by in situ generated µ-Cl−, giving rise to a rare Cu chain structure containing two kinds of magnetic exchange pathways. Variable temperature magnetic measurements revealed that both N–N and Cl− bridges convey antiferromagnetic couplings, with the best fitting JN–N = − 99.95 cm−1, JCl = − 5.70 cm−1, zj = − 1.17 cm−1 and g = 2.00.

The coupling reaction of 2-hydroxy-3-methoxybenzaldehyde with 3-amino-1,2-propanediol under solvothermal conditions gives Schiff-base ligand 3-[(2-hydroxy-3-methoxy)-phenylmethyleneamino]-1,2-propanediol (H3L). Further reaction of a polyhydroxy Schiff-base of H3L with Ln(NO3)3·6H2O and Ni(NO3)2·6H2O in the presence of triethylamine as the base afforded three heterdimetallic clusters with defective dicubic topology, namely, [Ln2Ni2(L)2(μ3-OMe)2(CH3CN)2(NO3)4]·2CH3CN (Ln = Sm (1), Er (2), Gd (3)). They were characterized by single-crystal X-ray diffraction, thermal analysis, IR spectroscopy, elemental analyses, and magnetic susceptibility. The magnetic studies of 1 and 2 revealed the presence of dominant antiferromagnetic interactions, and compound 3 exhibited ferromagnetic coupling and a large magnetocaloric effect with 17.85 J kg−1 K−1 at 2 K for ΔH = 5 T.

When reaction conditions change, products with different shapes and connections are usually obtained. Thus, the fine-tuning of structures in crystal engineering is challenging. We used the bisacylhydrazone ligand (H4L1, N′2,N′9-bis((E)-2-hydroxybenzylidene)-1,10-phenanthroline-2,9-dicarbohydrazide) with multiple coordination sites to react with Dy(OAc)3·6H2O under different pH conditions and subsequently obtain three pentanuclear dysprosium clusters 1–3 with the same shape. Fine-tuning the pH of the reaction solution resulted in different coordination environments of the metal center Dy5 in the structure of clusters 1–3. When the pH of the reaction solution was 6.4, only cluster 1 was obtained, and its Dy5 in the coordination environment of NO6 was provided by the ligand (L1)4−, the OH− bridge, and OAc−. When the pH was 6.6, only the pentanuclear cluster 2 was obtained, and its Dy5 in the NO7 coordination environment was provided by the ligand (L1)4−, OH− bridge, OAc−, and H2O coordinated by the end group. When the pH was 9.0, the metal center Dy5 of the obtained cluster 3 was in the NO7 coordination environment provided by the ligand (L1)4−, the bridge OAc−, and the end-group coordination CH3OH. In addition, we changed the ligand to H4L2 (N′2,N′9-bis((E)-2-hydroxy-3-methylbenzylidene)-1,10-phenanthroline-2,9-dicarbohydrazide) with a –CH3 substituent. When the pH was 6.8, the pentanuclear dysprosium cluster 4 with the same shape was also obtained. The metal center Dy5 of cluster 4 was in the coordination environment of NO6 provided by the ligand (L2)4−, CH3O−, and OAc−. When the pH was 9.2, only the hexanuclear dysprosium cluster 5, whose shapes and connections are completely different from clusters 1–4 and formed by CO32− bridges, was obtained. The CO32− source in the structure of cluster 5 was the same as the CO2 in the air. These examples of liquid–gas reaction in solvothermal reaction are rare. Furthermore, the increase in the steric hindrance of the substituents on the ligand is not conducive to the fine-tuning of the structure of the cluster but is conducive to the formation and connection of clusters with completely different shapes. As far as we know, this study is the first to use pH in manipulating the fine-tuning of a series of lanthanide clusters with the same shape.

Six dinuclear lanthanide(III) nitrato complexes [Ln(NO(3))(3)(H(2)O)](2)(μ-tppz) (where tppz = 2,3,5,6-tetra(2-pyridyl) pyrazine and Ln(III) = Nd (1), Sm (2), Eu (3), Gd (4), Tb (5), and Dy (6)) with bis-tridentate N-heterocyclic 2,3,5,6-tetra(2-pyridyl)pyrazine as bridging ligand have been solvothermally synthesized and characterized via elemental analysis, infrared spectroscopy, thermogravimetric analysis, single-crystal X-ray diffraction, and powder X-ray diffraction. The 3-D Hirshfeld surface and 2-D fingerprint plots show that the main interactions in 1–6 are the O⋯H/H⋯O intermolecular interactions with relative contributions of about 62%. Although the poor lanthanide(III)-centered luminescence properties clearly point to the efficiency of nonradiative quenching processes (presence of water molecules in the coordination sphere of the lanthanide(III) ions), the ligand tppz is better suited to sensitize the lanthanide(III)’s emissions of Eu(III) and Nd(III) than Sm(III), Tb(III), and Dy(III). Finally, the magnetic data of Dy(III) comple×6 reveals antiferromagnetic coupling between Dy(III) ions.

The generation of two types of complexes with different topological connections and completely different structural types merely via the substitution effect is extremely rare, especially for −CH3 a...

2-(2,3-Dihydroxpropyliminomethyl)6-methoxyphenol (H3L), trimethylacetic acid (Hpiv), Dy(NO3)3·6H2O and Co(NO3)2·6H2O were reacted at 80 °C to obtain a heterometallic hexanuclear cluster [Dy2Co4(L)2(μ3-OH)2(piv)8]·2Hpiv·2H2O (1). X-ray crystallographic study reveals that complex 1 displays a central planar butterfly motif consisting of the Dy 2 III Co 2 II , with another two CoII ions ‘‘capping’’ around the periphery of the butterfly. Magnetic studies suggest that 1 displays little out-of-phase component of the ac-susceptibilities in zero dc-field, and observed weak imaginary component.

Reactions of lanthanide nitrate, nickel nitrate, and polyhydroxyl Schiff-base ligand 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H4L) gave rise to a family of butterfly heterotetranuclear 3d–4f clusters formulated as [Ln2Ni2(H2L)2(μ3-OCH3)2(CH3CN)2(NO3)4]·2CH3OH·2H2O [Ln = Pr (1), Sm (2), Eu (3), Tb (4), Er (5)]. Single-crystal X-ray diffraction (XRD) reveals these complexes crystallize in the monoclinic space group P21/c. Both Ln1 and its symmetric Ln1A are coordinated to nine oxygen atoms and consist of two ligands with the same coordination mode μ3.η1:η2:η1:η2:η1, two nitrate ions and one μ3-OCH3. The five heterotetranuclear $${\text{Ni}}^{\text{II}}_{2} {\text{Ln}}^{\text{III}}_{2}$$ complexes display a central planar butterfly topology. The vertices of the body positions of the butterfly are occupied by NiII ions in all five complexes, which have been characterized by single-crystal X-ray diffraction, infrared spectroscopy, element analyses, powder X-ray diffraction and thermal gravimetric analyses. The magnetic properties of the complexes have been studied. The results show that complexes 1-3, and 5 exhibit antiferromagnetic exchange between the paramagnetic species, and 4 shows strong ferromagnetic interaction. We have shown the successful design and assembly of a new family of tetranuclear, dicationic, heterometallic $$\left\{ {{\text{Ni}}^{\text{II}}_{2} {\text{Ln}}^{\text{III}}_{2} } \right\}$$ complexes characterized by a butterfly-type topology. The results might be promoting the rational design and synthesis of 3d–4f molecule-base magnets materials with fascinating topologies and magnetic behaviours.

The synthesis, structure, and magnetic properties of a tetrairon(III) complex [Fe4(μ2-O)2Cl4(L)4]·0.5H2O (1, L = 2-methyl-8-hydroxyquinoline), which was prepared under solvothermal conditions and characterized by IR spectra, elemental analysis, TG, and single-crystal X-ray crystal diffraction, are presented. Each Fe center adopts a distorted trigonal bipyramid geometry and is coordinated with three oxygen atoms, one nitrogen atom, and one chlorine atom. Each 2-methyl-8-hydroxyquinoline is coordinated to two FeIII ions with μ2-η2:η1 coordination mode. The magnetic properties of the complex are dominated by antiferromagnetic exchange interactions.

In the present study, we designed and synthesized a triangular-shaped Dy3 single-molecule toroic with an energy barrier of 130 K. The above Dy3 cluster has the highest energy barrier among the reported triangular-shaped Ln3 single-molecule toroics. For the first time, Electrospray Ionization Mass Spectrometry (ESI-MS) was used to study the gradual splitting of a trigonal lanthanide cluster, which provided a reference for studying the assembly mechanism. The time-dependent ESI-MS technique was used to track the changes of reaction species, and a multi-step assembly mechanism for Dy3 clusters was proposed in combination with the fracture mechanism: [Dy(L)]+ → [Dy2(L)3]+ → [Dy3(L)4]+ → [Dy3(L)5]+/[Dy3(L)5]′+.

The organic ligands 5,7-dibromo-2-methyl-8-quinolinol (L1), 1,10-phenanthroline (L2), and 5,7-dichloro-2-methyl-8-quinolinol (L3) were used to react with Dy(NO3)3·6H2O under solvothermal conditions at 80 °C to obtain the complexes [Dy(L1)3(H2O)] (1), [Dy(L2)2(NO3)3] (2), and [Dy(L3)3(H2O)] (3), respectively. The reaction of L1 and L2 with lanthanide(iii) nitrate salts in the presence of triethylamine as a base afforded four mononuclear complexes, namely, [Ln(L1)2(L2)(NO3)] [Ln = Dy (4), Ho (5), Er (6), and Tb (7)]. Complexes 1 and 2 emitted yellow-green and red light under excitation with light of a certain wavelength. Interestingly, 4-7 exhibited a superimposition of the luminescence of 1 and 2. To our knowledge, this is the first example of the use of different organic light-emitting ligands to adjust the fluorescence of Ln(iii) complexes. Moreover, the series of complexes [Ln(L3)2(L2)(NO3)] [Ln = Dy (8), Ho (9), Er (10), and Tb (11)] were also obtained under the same conditions by replacing L1 with L3. In the way that was expected, 8-11 exhibited a superimposition of the luminescence of 2 and 3. Density functional theory (DFT) calculations of electron cloud density showed that the electron cloud densities of complexes 4 and 8 are mainly concentrated in the quinoline rings. Furthermore, analysis of the molecular ion peaks of complexes 4-11 obtained by electrospray mass spectrometry (ESI-MS) showed that only the 1,10-phenanthroline ligand was discovered to dissociate in the solution state. Magnetic measurements of the Dy-containing complexes revealed features of field-induced single-ion magnet behavior.

A family of novel Ln nanoclusters, namely, [Ln11(ovpho)4(μ-CH3O)2(μ-H2O)2(μ3-OH)6(CH3OH)4(H2O)2(NO3)8](OH)·xH2O·yCH3OH [Ln = Gd (1), x = 1, y = 3; Ln = Tb (2), x = 1, y = 3; Ln = Dy (3), x = 0, y = 3], was obtained via solvothermal reactions of Ln(NO3)3 with a diacylhydrazone ligand N,N'-bis(o-vanillidene)pyridine-2,6-dicarbohydrazide N-oxide (H4ovpho). Their isostructural molecular structures are composed of two crystallographically symmetric {Ln6} rings sharing a Ln3+ ion, and display an unprecedented "double boat conformation" topology that, to our knowledge, has not yet been reported. Ophenol, Oenol and Ooxynitride from ovpho4- ligands, as well as Omethanol, Owater and Ohydroxyl help to bridge the Ln3+ ions. The structural variation between these {Ln11} clusters and a previously reported {Gd18} nanowheel, both of which are assembled by H4ovpho under the same synthetic method and reaction conditions, is caused only by changing the anions of Ln salts. Magnetic investigations revealed a large magnetocaloric effect (MCE) of 1, whose maximum -ΔSm value reaches 30.1 J kg-1 K-1 for ΔH = 50 kOe at 2.0 K. Additionally, it was found that 3 shows single-molecule magnets (SMMs) behavior, with an approximated energy barrier Ueff = 6.13 K and pre-exponential factor τ0 = 1.70 × 10-6 s.