A 3D Hybrid Praseodymium-Antimony-Oxochloride Compound: Single-Crystal-to-Single-Crystal Transformation and Photocatalytic Properties

Mixed-valence compounds based on heterometallic-oxo-clusters containing Sb(III,V): crystal structures and proton conduction

Two isostructural Co(Cd)-antimony-oxo tartrate cluster-based compounds with a one-dimensional (1-D) belt-like structure, namely H9.2[Co(H2O)6]{M0.5(H2O)3.5{M'(H2O)4[SbVO6[Co4.2(H2O)5SbIII6(μ3-O)2(tta)6]]}}2·nH2O (M = Co, M' = Co, n = 9 (1); M = Cd0.39/Co0.61, M' = Cd0.24/Co0.76, n = 7 (2); H4tta = tartaric acid), have been synthesized by solvothermal methods. It is noteworthy that the relatively rare mixed-valence Sb(III,V) exists in the structures. The anionic clusters in both compounds appear to be in a sandwich configuration; the top and bottom layers are based on {Sb3(μ3-O)(tta)3} brackets, and the intermediate layer is occupied by {SbVO6[Co4.2(H2O)5]}. The title compounds have been characterized by single-crystal X-ray diffraction, powder X-ray diffraction, elemental analyses, thermogravimetric analyses, and UV-Vis spectroscopy. We chose compound 2 as a representative to test its proton conductivity, and the results show that the conductivity can reach 1.42 × 10-3 S cm-1 at 85 °C under 98% relative humidity.

Structural Evolution and Properties of Praseodymium Antimony Oxochlorides Based on a Chain-like Tertiary Building Unit

Unveiling the structural evolution of single-crystalline compounds based on certain building units may help greatly in guiding the design of complex structures. Herein, a series of praseodymium antimony oxohalide crystals have been isolated under solvothermal conditions via adjusting the solvents used, that is, [HN(CH2CH3)3][FeII(2,2′-bpy)3][Pr4Sb12O18Cl15]·EtOH (1) (2,2′-bpy = 2,2′-bipyridine), [HN(CH2CH3)3][FeII(2,2′-bpy)3]2[Pr4Sb12O18Cl14)2Cl]·N(CH2CH3)3·2H2O (2), and (H3O)[Pr4Sb12O18Cl12.5(TEOA)0.5]·2.5EtOH (3) (TEOA = mono-deprotonated triethanolamine anion). Single-crystal X-ray diffraction analysis revealed that all the three structures feature an anionic zig-zag chain of [Pr4Sb12O18Cl15−x]n as the tertiary building unit (TBU), which is formed by interconnections of praseodymium antimony oxochloride clusters (denoted as {Pr4Sb12}) as secondary building units. Interestingly, different arrangements or linkages of chain-like TBUs result in one-dimensional, two-dimensional layered, and three-dimensional structures of 1, 2, and 3, respectively, thus demonstrating clearly the structural evolution of metal oxohalide crystals. The title compounds have been characterized by elemental analysis, powder X-ray diffraction, thermogravimetric analysis, and UV-Vis spectroscopy, and the photodegradation for methyl blue in an aqueous solution of compound 1 has been preliminarily studied. This work offers a way to deeply understand the assembly process of intricate lanthanide-antimony(III) oxohalide structures at the atomic level.

Single-Crystal Superstructures via Hierarchical Assemblies of Giant Rubik's Cubes as Tertiary Building Units

Intricate superstructures possess unusual structural features and promising applications. The preparation of superstructures with single-crystalline nature are conducive to understanding the structure-property relationship, however, remains an intriguing challenge. Herein we put forward a new hierarchical assembly strategy towards rational and precise construction of intricate single-crystal superstructures. Firstly, two unprecedented superclusters in Rubik's cube's form with a size of ≈2×2×2 nm³ are constructed by aggregation of eight {Pr₄ Sb₁₂ } oxohalide clusters as secondary building units (SBUs). Then, the Rubik's cubes further act as isolable tertiary building units (TBUs) to assemble diversified single-crystal superstructures. Importantly, intermediate assembly states are captured, which helps illustrate the evolution of TBU-based superstructures and thus provides a profound understanding of the assembly process of superstructures at the atomic level.

Proton-conducting layered structures based on transition metal oxo-clusters supported by Sb(iii) tartrate scaffolds

Two transition metal-antimony oxo-cluster based compounds, H₅{MCd(H₂O)₆[M(H₂O)₃Co₃Sb^VSb(μ₃-O)₈(l-tta)₆]}·7H₂O (1) (M = Cd_0.5 + Co_0.5) and H₃K₅(H₂O)₁₁{Cd(H₂O)₄[Cd(H₂O)Fe₄Cd₂Sb₆(μ₄-O)₅(μ₃-O)₃(l-tta)₆][Cd(H₂O)₂Fe₄Cd₂Sb₆(μ₄-O)₄(μ₃-O)₄(l-tta)₆][Cd(H₂O)₂Fe₄Cd₂Sb₆(μ₄-O)₄(μ₃-O)₄(l-tta)₆Cd(H₂O)₅]}·17H₂O (2) (L-H₄tta = l-tartaric acid) were hydrothermally synthesized and characterized. Compound 1 features a [MCo₃Sb^VSb(μ₃-O)₈(l-tta)₆(H₂O)₃]^9- cluster, while compound 2 contains three types of clusters, namely, [Cd(H₂O)Fe₄Cd₂Sb₆(μ₄-O)₅(μ₃-O)₃(l-tta)₆]^4-, [Cd(H₂O)₂Fe₄Cd₂Sb₆(μ₄-O)₄(μ₃-O)₄(l-tta)₆]^4- and [Cd(H₂O)₂Fe₄Cd₂Sb₆(μ₄-O)₄(μ₃-O)₄(l-tta)₆Cd(H₂O)₅]^2-. All the clusters are of sandwich-type with {Sb₃(μ₃-O)(l-tta)} scaffolds on the top and bottom. The Cd (and M in 1) ions interconnect the clusters into layered structures in both compounds. To the best of our knowledge, this is the first report of transition metal-antimony oxo-clusters that simultaneously contain the first-row and second-raw transition metal ions, and compound 1 represents the first example of such type of clusters that contain Sb(v). The two compounds exhibit proton conductivity with the values of 2.43 × 10^-3 and 2.95 × 10^-3 S cm^-1 at 85 °C under 98% relative humidity, respectively.

Krebs-Type {M2(WO2)2[B-β-SbW9O33]2}n- (M = SbIII, (WO3)) Tungstoantimonate Possessing Unique Pseudo-Seesaw Sb-O Structure

Two new Krebs-type tungstoantimonates (H₂en)₈H₆{[Sb₂(WO₂)₂(B-β-SbW₉O₃₃)₂][(WO₂)₂(WO₃)₂(B-β-SbW₉O₃₃)₂]}·22H₂O (1) and (H₂en)₇[(WO₂)₂(WO₃)₂(B-β-SbW₉O₃₃)₂]·12H₂O (2) were synthesized and characterized. Notably, crystal 1 possesses a specific pseudo-seesaw SbO₄ subunit in the central metal belt of [Sb₂(WO₂)₂(B-β-SbW₉O₃₃)₂]^12- species, which is rare in reported Krebs-type polyoxometalates. One of the structural features is that there are two kinds of Krebs-type polyanionic clusters in crystal 1 labeled as {(WO₂)₂(WO₃)₂(B-β-SbW₉O₃₃)₂} (part A) and {Sb₂(WO₂)₂(B-β-SbW₉O₃₃)₂} (part B), respectively. The subunits A and B are alternately connected through Sb-O-W bonds into a chain-like structure of inorganic clusters. Moreover, the catalytic property of crystals 1 and 2 for electron-transfer reaction were investigated by transferring K₃[Fe(CN)₆] into K₄[Fe(CN)₆].

[Ba13Sb36Cl34O54]8-: high-nuclearity cluster for the assembly of nanocluster-based compounds

Herein, we report two nanocluster-based compounds built on an unprecedented cluster [Ba₁₃Sb₃₆Cl₃₄O₅₄]^8-, which represents the first example of a discrete alkaline earth (AE)-containing oxochloride cluster and the largest Sb-based oxohalide cluster to date; the proton-conducting property of the compounds was investigated.

Solvent-mediated crystal-to-crystal transformations from a cationic homometallic metal–organic framework to heterometallic frameworks

A new strategy for the synthesis of heterometallic metal–organic frameworks (MOFs) was presented. Two unprecedented heterometallic MOFs were successfully prepared through solvent-mediated crystal-to-crystal transformations from a monometallic cationic MOF.

Syntheses, structures and photocatalytic properties of five new praseodymium–antimony oxochlorides: from discrete clusters to 3D inorganic–organic hybrid racemic compounds

Presented here are five Pr–Sb–O–Cl cluster-based compounds with structures from discrete organic-decorated cluster to 3D framework that exhibit photocatalytic H₂-evolution activity and magnetic properties.