Self-Assembly of Lanthanide-Aluminum Cluster-Organic Frameworks with Magnetocaloric Effect and Luminescence.

The self-assembly of the lanthanide metal-organic frameworks presents a formidable challenge but profound significance. Compared with the metal-organic frameworks based on 4f-3d ions, the chemistry of 4f-3p metal-organic frameworks has not been fully explored so far. In this study, two lanthanide-aluminum-based clusters [Ln6Al(IN)10(µ3-OH)5(µ3-O)3(H2O)8]·xH2O (x = 2, Ln = Gd, abbreviated as Gd6Al; x = 2.5, Ln = Eu, abbreviated as Eu6Al; HIN = isonicotinic acid) have been meticulously designed and obtained by hydrothermal reaction at low pH. The crystallographic study revealed that both Gd6Al and Eu6Al clusters exhibit an unprecedented sandwiched metal-organic framework holding a highly ordered honeycomb network. To our knowledge, it is the first case of Ln-Al-based cluster-organic frameworks. Furthermore, magnetic investigation of Gd6Al manifests a decent magnetic entropy change of -ΔSmmax = 28.8 J kg-1 K-1 at 2 K for ΔH = 7.0 T. Significantly, the introduction of AlIII ions into the lanthanide metal-organic frameworks displays excellent solid-state luminescent capability with a lifetime of 371.6 µs and quantum yield of 6.64%. The construction and investigation of these two Ln-Al clusters represent great progress in the 4f-3p metal-organic framework.

An iron-containing POM-based hybrid compound as a heterogeneous catalyst for one-step hydroxylation of benzene to phenol.

It is a major challenge to perform one-pot hydroxylation of benzene to phenol under mild conditions, which replaces the environmentally harmful cumene method. Thus, finding highly efficient heterogeneous catalysts that can be recycled is extremely significant. Herein, a (POM)-based hybrid compound {[FeII(pyim)2(C2H5O)][FeII(pyim)2(H2O)][PMoV2MoVI9VIV3O42]}·H2O (pyim = 2-(2-pyridyl)benzimidazole) (Fe2-PMo11V3) was successfully prepared by hydrothermal synthesis using typical Keggin POMs, iron ions and pyim ligands. Single-crystal diffraction shows that the Fe-pyim unit in Fe2-PMo11V3 forms a stable double-supported skeleton by Fe-O bonding to the polyacid anion. Remarkably, due to the introduction of vanadium, Fe2-PMo11V3 forms a divanadium-capped conformation. Benzene oxidation experiments indicated that Fe2-PMo11V3 can catalyze the benzene hydroxylation reaction to phenol in a mixed solution of acetonitrile and acetic acid containing H2O2 at 60 °C, affording a phenol yield of about 16.2% and a selectivity of about 94%.

Constructing Two Cu-Modified Organophosphomolybdates from a Nanocluster to a One-Dimensional Chain for Boosted Visible-Light-Driven Hydrogen Production.

Photocatalytic decomposition of water to produce hydrogen H2 is an ideal way to solve energy and environmental problems, and the development of highly efficient polyoxometalate catalysts for photocatalytic hydrogen production has attracted wide attention. Herein, two Cu-modified Strandberg-type organophosphomolybdates were successfully synthesized, [Cu(C8H7N3)(H2O)2]2[(C6H5PO3)2Mo5O15]·4H2O (1) and [Cu(phen)(H2O)][Cu(phen)(H2O)2][(C6H5PO3)2Mo5O15]·2H2O (2) ([(C6H5P)2Mo5O21]Cu2) (C8H7N3 = 2-(1H-pyrazol-3-yl)pyridine, phen = 1,10-phenanthroline). Two Strandberg-type organophosphomolybdates can be used for visible-light-driven hydrogen production. Also, compound 2 exhibits an H2 production rate of 6399 µmol g-1 h-1 after 8 h light exposure in the presence of photosensitization agent [Ir(dtbbpy)(ppy)2][PF6] and TEOA. In addition, cyclic tests showed that compound 2 could be recycled four times without a significant reduction in catalytic performance. This work offers fresh insight into the development of novel polyoxometalates for efficient hydrogen evolution.

MoO42--templated Ln20Ni21 heterometallic clusters with large low-field magnetic entropy.

The anionic template method is an effective strategy for synthesizing high-nuclearity transition-lanthanide (3d-4f) heterometallic clusters. Herein, two lanthanide clusters with formulas [Gd20Ni21(µ3-OH)21(CO3)6(IDA)21(C2H4NO2)6(C2O4)3(MoO4)1.5(µ2-OH)1.5(H2O)9]Cl10.5·79H2O (1) and [Tb20Ni21(µ3-OH)21(CO3)6(IDA)21(C2H4NO2)6(C2O4)3(MoO4)(µ2-OH)2(H2O)10]Cl11·32H2O (2) were synthesized by introducing MoO42- anions as templates. Structural analysis indicates that compounds 1 and 2 are isomorphic, featuring a fascinating triangular-shaped metal framework. Magnetic property investigations illuminate the fact that compound 1 exhibits a large -ΔSm of 37.83 J kg-1 K-1 at 3 K for ΔH = 7 T. In particular, it is worth mentioning that compound 1 has an excellent low-field magnetic entropy (-ΔSm = 23.85 J kg-1 K-1 at 2 K, 2 T).

Two bimetal-doped (Fe/Co, Mn) polyoxometalate-based hybrid compounds for visible-light-driven CO2 reduction.

Two polyoxometalate (POM)-based hybrid compounds have been successfully designed and constructed by the hydrothermal method with molecular formulas [K(H2O)2FeII0.33Co0.67(H2O)2(DAPSC)]2{[FeII0.33Co0.67(H2O)(DAPSC)]2[FeII0.33Co0.67(H2O)4]2[Na2FeIII4P4W32O120]}·21.5H2O (1), and [Na(H2O)2FeII0.33Mn0.67(H2O)2(DAPSC)]2{[FeII0.33Mn0.67(H2O)(DAPSC)]2[FeII0.33Mn0.67(H2O)4]2[Na2FeIII4P4W32O120(H2O)2]}·24H2O (2) (DAPSC = 2,6-diacetylpyridine bis-(semicarbazone)), respectively. Structural analysis revealed that 1 and 2 consisted of metal-organic complexes containing DAPSC ligands with dumbbell-type inorganic clusters, iron-cobalt (iron-manganese) and some other ions. By utilizing a combination of strongly reducing {P2W12} units and bimetal-doped centres the CO2 photoreduction catalytic capacity of 1 and 2 was improved. Notably, the photocatalytic performance of 1 was much better than that of 2. In CO2 photoreduction, 1 exhibited CO selectivity as high as 90.8%. Furthermore, for 1, the CO generation rate reached 6885.1 µmol g-1 h-1 at 8 h with 3 mg, and its better photocatalytic performance was presumably due to the introduction of cobalt and iron elements to give 1 a more appropriate energy band structure. Further recycling experiments indicated that 1 was a highly efficient CO2 photoreduction catalyst, which could still possess catalytic activity after several cycles.

Layered Co-O Cluster Applied to Photocatalytic CO2 Reduction.

In the field of recycling CO2, the photocatalytic CO2 reduction reaction (CO2RR) is a typical example, and researchers have designed a variety of photocatalysts to improve the conversion rate of CO2 over the years. In this paper, two metal-oxygen clusters are designed and formulated as [Co3Zn(OH)6(SO4)]·4H2O (1) and [Ni3Zn(OH)6(SO4)]·4H2O (2). As for compound 1, the main structure is composed of {CoO6} octahedra connected by edge-sharing to form a two-dimensional layer, on which {ZnO4} and {SO4} tetrahedra are supported. More interestingly, compound 1 has outstanding photocatalytic activity, which is mainly attributed to the open-framework structure and the cobalt ions as active sites. Upon catalysis for eight hours, its maximum CO generation rate is 9982.13 µmol g-1 h-1, with a selectivity of 81.8%. Additionally, compound 1 takes on weak antiferromagnetic coupling due to Co(II) ions.

Two Windmill-Shaped Ln18 Nanoclusters Exhibiting High Magnetocaloric Effect and Luminescence.

The self-assembly of the high-nuclearity Ln-exclusive nanoclusters is challenging but of significance due to its aesthetically pleasing architectures and far-reaching latent applications in magnetic cooling technologies. Herein, two novel high-nuclearity lanthanide nanoclusters were successfully synthesized under solvothermal conditions, formulated as {[Gd18(IN)20(HCOO)8(µ6-O)(µ3-OH)24(H2O)4]·4H2O}n and {[Eu18(IN)16(HCOO)8(CH3COO)4(µ6-O)(µ3-OH)24(H2O)4]·5H2O}n (abbreviated as Gd18 and Eu18, HIN = isonicotinic acid). Both of them possess novel and exquisite windmill-shaped cationic cores in the family of high-nuclearity Ln-exclusive nanoclusters. Remarkably, the adjacent second building units are interconnected into a three-dimensional (3D) metal-organic framework by IN- ligands. As expected, the abundant existence of GdIII ions endows Gd18 with a favorable magnetic entropy change at 2.0 K for ΔH = 7.0 T (-ΔSmmax = 40.0 J kg-1 K-1), and Eu18 displays the typical luminescence of EuIII ions.

Efficient Visible-Light-Driven Hydrogen Production over Cu-Modified Polyoxotungstate Hybrids.

Hydrogen energy is a renewable and clean source, which makes a great difference in future sustainable energy systems. Visible-light-driven photocatalysis reaction involves harnessing the abundance of sunlight for hydrogen production among many catalytic technologies. However, the fabrication of photocatalysts that have distinctive performance in visible light is still the primary challenge. Herein, two new Cu-modified polyoxotungstate hybrids, {[Cu2(bim)4(H2O)2](HBW12O40)2·(H2bim)2·8H2O} (1) (bim = [1,1'-methylenebis(1H-imidazole)]) and {[Cu2(bim)4(H2O)2](H3PW10Ti2O40)2·(H2bim)2·8H2O} (2), have been successfully isolated by bridging two saturated Keggin polyoxotungstates and copper-azole complexes. Not surprisingly, 2 holds higher reduction activity due to the more negative charge and stronger basicity on the terminal oxygen of Ti═O and bridge oxygen of Ti-O-W. The H2 yield was 17075 µmol g-1 h-1 for 2 in the tunable light-driven H2 production system, which is promising in the field of photocatalysis.

Two 1D Anderson-Type Polyoxometalate-Based Metal-Organic Complexes as Bifunctional Heterogeneous Catalysts for CO2 Photoreduction and Sulfur Oxidation.

Sulfur oxides from the combustion of petrol and excessive emissions of carbon dioxide (CO2) are currently the main causes of environmental pollution. Considerable interest has been paid to solving the challenge, and catalytic reactions seem to be the desired choice. Due to the high density of Lewis acid active sites, polyoxometalates are considered to be the ideal choice for these catalytic reactions. Herein, two captivating polyoxometalate-based metal-organic complexes, formulated as [Co(H2O)2DABT]2[CrMo6(OH)5O19] ({Co-CrMo6}) and [Zn(H2O)2DABT]2[CrMo6(OH)5O19] ({Zn-CrMo6}) (DABT = 3,3'-diamino-5,5'-bis(1H-1,2,4-triazole)) were successfully obtained under hydrothermal conditions. The structural analysis demonstrates that {Co-CrMo6} and {Zn-CrMo6} are isostructural with two different transition metal (Co/Zn) ions based on quadridentate Anderson-type [CrMo6(OH)5O19]4- polyanions. A fan-shaped unit of {Co-CrMo6}/{Zn-CrMo6} is linked to generate a one-dimensional (1D) ladder-like structure. Intriguingly, benefitting from rich Co centers with a suitable energy band structure, {Co-CrMo6} displays better photocatalytic activity than {Zn-CrMo6} for converting CO2 into CO, endowing the CO formation of 1935.3 µmol g-1 h-1 with high selectivity. Meanwhile, {Co-CrMo6} also exhibits a satisfactory removal rate of 99% for oxidizing dibenzothiophene at 50 °C, which suggests that {Co-CrMo6} may be utilized as a potential dual functional material with immense prospects in photocatalytic CO2 reduction and sulfur oxidation for the first time.

An isolated doughnut-like molybdenum(V) cobalto-phosphate cluster exhibiting excellent photocatalytic performance for carbon dioxide conversion.

An isolated doughnut-like molybdenum(V) cobalto-phosphate cluster with the formula (C11NH10)2{[Co(H2O)6]@[H29Co16Mo16(H2O)16(PO4)24O36]}(H2PO4)·25H2O has been successfully synthesized by a hydrothermal method. Single crystal X ray diffraction analysis shows that four {Co4O60} tetramers and eight {Mo2O10} dimers are linked by oxygen atoms and phosphate groups to construct a doughnut-type structure for [Co@{Co16Mo16}], in which one [CoII(H2O)6]2+ octahedron is enclosed. More importantly, [Co@{Co16Mo16}] exhibits promising photocatalytic performance for CO2 reduction with the CO formation rate of 6764.3 µmol g-1 h-1 and the selectivity of 96.89%. In addition, the cycling test indicated that [Co@{Co16Mo16}] can be reused for at least four cycles without significant loss of catalytic activity. The result of this work may provide new insight for the synthesis of highly efficient POM-based photocatalysts for CO2 reduction.

Two POM-based compounds containing Zn-capped Keggin anions as decent heterogeneous catalysts for sulfur oxidation and CO2 cycloaddition reactions.

Carbon dioxide (CO2) and the combustion of sulfide in gasoline are the main causes of air pollution. A great deal of attention has been paid to solving the problem and the catalytic reaction seems to be a decent choice. Due to the high-density of Lewis acidic active sites, polyoxometalates are undoubtedly an ideal choice for the sulfur oxidation reaction. With the reasons foregoing, two novel Zn-capped polyoxometalate-based organic-inorganic hybrids, {[α-PMoV2MoVI10O39(OH)Zn2][bbbm]3}·0.5C2H5OH (1) and TBA2{[ε-PMoV8MoVI4O37(OH)3Zn4][phim]3} (2) ((where bbbm = 1-(4-imidazol-1-ylbutyl) imidazole) and phim = 2-phenylimidazole) were successfully obtained by hydrothermal synthesis. In the two compounds, the N-donor ligands in a monodentate or bidentate coordination mode are directly connected to the Keggin anions by Zn-capped atoms, forming an extended one-dimensional chain. It is noteworthy that compound 2 ends up with an interesting spiral infinite chain possibly thanks to the TBA+ cations residing in gaps as structure-directing agents. Simultaneously, the catalytic properties indicate that compounds 1 and2 as efficient heterogeneous catalysts display a decent catalytic activity in the sulfur removal process. Especially, 2 enabled satisfying catalytic oxidation of dibenzothiophene (DBT) to produce more valuable dibenzothiophene sulfone (DBTO2) at 55 °C, and the conversion almost reached 99%. Besides, compound 2 also shows satisfactory catalytic effectiveness in the oxidation of various epoxides in the CO2 cycloaddition reaction, which suggests that compound 2 has the potential to function as a dual functional material with tremendous prospects in sulfur oxidation and carbon dioxide cycloaddition for the first time.

A new family of boat-shaped Ln8 clusters exhibiting the magnetocaloric effect and slow magnetic relaxation.

Designing and synthesizing lanthanide clusters have always been a research hotspot. Herein, three lanthanide clusters with the formula [Ln8(IN)14(µ3-OH)8(µ2-OH)2(H2O)8]·xH2O (Ln = 1-Gd and x = 11; Ln = 2-Dy and x = 8; Ln = 3-Eu and x = 8) have been isolated in the presence of isonicotinic acid under solvothermal conditions. Structural analysis indicates that those three compounds are isostructural, featuring boat-shaped {Ln8} metal frameworks. Magnetic measurements reveal that 1-Gd exhibits a larger MCE with the maximum -ΔSm value of 31.77 J kg-1 K-1 at 2 K for ΔH = 7 T, while 2-Dy displays slow magnetization relaxation. Besides, the photoluminescence properties of 3-Eu were investigated.

Two Ni-Substituted Trilacunary Keggin-Type Polyoxometalates: Syntheses, Crystal Structures, NLO Studies, and Magnetic Properties.

Two Ni-substituted polyoxometalates (NiSPs), [Ni6(Py)6(H2O)5(µ3-OH)3(PW9O34)]2·10H2O (1), [Ni7(Py)6(Im)(H2O)5O(WO4)(µ3-OH)3(H2PW9O34)]·3H2O (2) (Py = pyridine, Im = imidazole), were successfully hydrothermally synthesized. Compounds 1 and 2 have significantly different configurations by introducing different amounts of imidazole ligands. For compound 1, two malposed {Ni6(Py)6PW9} units that are face to face are bridged by two Ni-O-W bonds to constitute an isolated dimeric structure. Differently, the {Ni7(Py)6(Im)PW9}2 dimer in compound 2 connects with four adjacent dimers by four {WO4} groups in an interesting two-dimensional (2-D) arrangement. The magnetism of compounds 1 and 2 was studied, and magnetic test results demonstrated that both compounds have ferromagnetic interactions between the nickel centers. Meanwhile, the third-order nonlinear optical (NLO) measurements indicated that compound 1 can serve as potential nonlinear optical materials.

A Purely Inorganic Quasi-Keggin Polyoxometalate for Photocatalytic Conversion of Carbon Dioxide to Carbon Monoxide.

A pure inorganic cluster, H47 Na2 Co4 Mo24 (PO4 )11 O72 ⋅ 15H2 O (denoted as {Co4 Mo24 }), has been successfully synthesized by hydrothermal method. Notably, the assembly of a central {Co2 PO4 } tetrahedron and four peripheral {Co[P4 Mo6 ]} fragments gives rise to a rare "quasi-Keggin" structure of {Co4 Mo24 }, in which Co linkers continue to bridge adjacent substructures, resulting in the generation of 3D framework with large cavities. Benefitting from the combination of strong reductive {P4 Mo6 } units and Co active centers, the photocatalytic system with {Co4 Mo24 } as heterogeneous catalyst exhibits excellent activity for CO2 conversion to CO, offering the CO formation rate of 1848.3 µmol g-1 h-1 with high selectivity of 97.0 %. Besides, thermogravimetric and X-ray diffraction analysis confirm that {Co4 Mo24 } can maintain stable during the photocatalytic reaction process.

Two three-dimensional polyanionic clusters [M(P4Mo6)2] (M = Co, Zn) exhibiting excellent photocatalytic CO2 reduction performance.

Two captivating {P4Mo6}-based compounds, formulated as (H2bbi)2{[Co2(bbi)][Co2.33(H2O)4][H9.33CoP8Mo12O62]}·4H2O (1) and (H2bbi){[Zn(Hbbi)]2[Zn0.75(bbi)][K2Zn(H2O)4][H8.5ZnP8Mo12O62]} (2) [bbi = 1,1'-(1,4-butanediyl)bis(imidazole)], were successfully synthesized under hydrothermal conditions. Structural analysis demonstrates that compounds 1 and 2 are constructed from hourglass-shaped structures [M(P4Mo6O31)2]n- (M = Co, Zn), which are all made up of molybdophosphates and one transition metal ion as the central connecting node. Compounds 1 and 2 feature three-dimensional (3D) frameworks, which are all connected to form a 3D structure by metal ions and bbi ligands. More interestingly, compound 1 exhibits higher catalytic activity than 2 in CO2 photoreduction due to the suitable energy band structure of Co species in {P4Mo6} clusters. The CO yield was 3261 µmol g-1 with high selectivity in 8 h for compound 1 in photocatalytic CO2 reduction, which is highly promising in the photocatalytic field. Additionally, the photoluminescence properties of 2 were investigated.

Two Polyoxometalate-Based Hybrid Compounds Modified by Iron Schiff Base Complexes: Syntheses, Crystal structures, Cyclic Voltametric Studies and Nonlinear Optical Properties.

Two new polyoxometalate (POM)-based hybrid compounds modified by a Schiff base, [Fe(DAPSC)(H2 O)2 ]2 [HPMo2 V Mo10 VI O40 ] ⋅ 5H2 O (1) and [Fe(DAPSC)(H2 O)]2 [HPV3 IV Mo4 V Mo7 VI O42 ] ⋅ 6H2 O (2), (DAPSC=2,6-diacetylpyridine bis-(semicarbazone)), have been successfully constructed from typical Keggin POMs, iron ions, and DAPSC ligands under hydrothermal condition. Structural analysis demonstrates that the Fe-Schiff base ligand units are free from polyacid anions in compound 1. While in compound 2, the Fe-Schiff base ligand units are bridged with polyacid anions via Fe-O bonds to emerge a stable double-supported skeleton. Noticeably, owing to the introduction of vanadium in H5 PMo10 V2 O40 ⋅ 32.5H2 O, a divanadium-capped configuration is shaped in compound 2. Besides, the third-order nonlinear optical (NLO) properties of two compounds were explored. It should be noted that both compounds 1 and 2 have two-photon absorption properties, which indicates that the two compounds are potential nonlinear optical materials.

Two new isolated Zn-ε-Keggin clusters modified by conjugated organic ligands with decent electrocatalytic and third-order NLO properties.

Two new bifunctional isolated hybrid compounds, [ε-PMoV8MoVI4O37(OH)3Zn4][iql]4·6H2O (1) and [ε-PMoV8MoVI4O38(OH)2Zn4][bipy]3[(CH3COO)(bipy)2Zn]·2H2O (2) (where iql = isoquinoline and bipy = 2,2'-bipyridine), based on Zn-ε-Keggin were successfully synthesized by self-assembly under hydrothermal conditions. It is interesting to note that acetate in 2 acted as a linker connecting the ε-Keggin anion with the one Zn atom (Zn5) and enabled the ε-Keggin anion to coordinate with more bipy ligands, culminating with a larger isolated system, which is the first reported isolated cluster of Zn5PMo12. Meanwhile, compounds 1-2 show great electrochemical behaviors and excellent electrocatalytic activity for the degradation of NaNO2. In addition, compound 2 displays better third-order NLO performance than 1 due to the presence of more conjugated rings, with a TPA cross section (σ) of 1819 GM, which suggests that compound 2 has the potential to function as a bifunctional material with tremendous prospects.

[Curative effect investigation and therapy selection of open Pilon fracture].

OBJECTIVE: To evaluate the treatment of open Pilon fractures. METHODS: A total of 126 open Pilon fracture cases were reviewed retrospectively. The patients were treated from February 1996 to March 2009, included 72 males and 54 females with an average age of 36 years old ranging from 17 to 65 years. According to the Ruedi-Augower classification, there were 28 cases of type I, 58 of type II, and 40 of type III. Among all the cases, 31 cases were treated with external fixators combined with limited internal fixations, 80 cases were treated with open reduction and internal fixation with anatomical plates, 15 cases with open reduction and cross K-wire fixations. RESULTS: All cases were followed-up for from 10 to 26 months with an average of 16 months. The average bone healing time was 10 weeks (from 8 to 14 weeks). According to the Mazur ankle function evaluation, the results were excellent in 89 cases, good in 26,fair in 9,poor in 2. The excellent and good rate was 91.2%. CONCLUSION: The "Personalized treatment principle" effectively prevents the occurrence of complications and helps to restore the joint functions.