A series of zirconium-oxo cluster complexes based on arsenate or phosphonate ligands

Chen, Guanghui; He, Yan‐Ping; Zhang, Shuhua; Zhang, Lei

doi:10.1016/j.inoche.2018.09.013

Cited by 8 publications

(2 citation statements)

References 25 publications

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“…However, these are not Zr6 clusters but rather two Zr 3 O(µ 2 −OR) 3 (OR) 3 units bridged by four phosphonates. 55,56 Such a structure can be regarded as the first step of the decomposition of the Zr6 clusters where the two Zr3 units are pushed apart. The tridentate coordination of phosphonates was not considered in our theoretical calculations, neither was the decomposition of the oxo cluster.…”

Section: Discussionmentioning

confidence: 99%

“…By direct synthesis from zirconium alkoxide and phosphonic acids, various oxoalkoxy clusters are formed instead of the Zr 6 O 8 unit. 55,56 Only from ZrCl 4 and dimethylphosphate ligands in dimethylformamide, a Zr 6 O 8 cluster was prepared. 57 Also in the case of titanium only various oxoalkoxy species are produced by reacting titanium alkoxides with phosphonic or diphenylphosphinic acid.…”

Section: Introductionmentioning

confidence: 99%

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Atomically precise surface chemistry of zirconium and hafnium metal oxo clusters beyond carboxylate ligands

Unniram Parambil,

Pokratath,

Parammal

et al. 2024

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The effectiveness of nanocrystals in many applications greatly depends on their surface chemistry. Here, we leverage the atomically precise nature of zirconium and hafnium oxo clusters to gain fundamental insight into the thermodynamics of ligand binding. Through a combination of theoretical calculations and experimental spectroscopic techniques, we determine the multifaceted interaction between the [M6O8]8+ (M = Zr, Hf) cluster surface and various ligands: carboxylates, phosphonates, dialkylphosphinates, and monosubstituted phosphinates. We refute the common assumption that the adsorption energy of an adsorbate remains unaffected by the surrounding adsorbates. We find that dialkylphosphinic acids are too sterically hindered to yield complete ligand exchange, even though a single dialkylphosphinate has similar binding affinity to a phosphonate. On the other hand, monoalkyl or monoaryl phosphinic acids replace carboxylates quantitatively and we obtained the crystal structure of M6O8H4(O2P(H)Ph)12 (M = Zr, Hf), giving a unique insight into the exact binding mode of monoalkylphosphinate. Finally, phosphonic acids cause a partial structural reorganization of the metal oxo cluster into amorphous metal phosphonate as indicated by pair distribution function analysis. These results rationalize the absence of phosphonate-capped M6O8 clusters and the challenge in preparing Zr phosphonate metal-organic frameworks. We further reinforce the notion that monoalkylphosphinates are carboxylate mimics with superior binding affinity.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Atomically precise surface chemistry of zirconium and hafnium metal oxo clusters beyond carboxylate ligands

Unniram Parambil,

Pokratath,

Parammal

et al. 2024

Preprint

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Metal–Organic Frameworks Based on Group 3 and 4 Metals

et al. 2020

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Metal-organic frameworks (MOFs), a class of porous crystalline framework materials, are linked by strong bonds between inorganic and organic building blocks. [1-3] In the past two decades, MOFs have rapidly grown as a star material due to their exceptional performance in areas such as storage, separation and catalysis. [4] The outstanding performance of MOFs in applications benefits from their intrinsically porous structures and highly tunable pore environment. [5-7] The creation and modification of pore space with optimized size, functionality and diversity can be precisely tuned at the molecular level by rationally designing building blocks and synthetic procedures. [8,9] The diversity of MOFs can be enriched by expanding the library of organic linkers with varying lengths, geometries, and functional groups. [10] Additionally, very diverse metal cations are applied to MOF synthesis, ranging from monovalent (Ag + , Cu + , etc.), divalent (Mg 2+ , Fe 2+ , Co 2+ , Ni 2+ , etc.), trivalent (Al 3+ , Sc 3+ , V 3+ , Cr 3+ , etc.), to tetravalent (Ti 4+ , Zr 4+ , Hf 4+ , etc.) cations. [11] In this review, we mainly focus on MOFs with group 3 and 4 metals, including Y, lanthanides (Ln, from La to Lu), actinides (An, from Ac to Lr), Ti, and Zr (Figure 1). Group 3 metal cations are generally found in the oxidation state of +3 in the MOF structures, while group 4 metal cations mainly exist in the oxidation state of +4, leading to the formation of much stronger coordination bonds with carboxylates. [12] Therefore, group 4 metal-based MOFs (M IV-MOFs) generally have enhanced stability compared with MOFs constructed from metals of group 3 and other groups. This series of MOFs stands out because the involved metals can generally coordinate with carboxylates to form frameworks with strong coordination bonds, according to the Pearson's hard/soft acid/base principle, where group 3 and 4 metal cations are regarded as hard acids while carboxylate ligands are hard bases. [11] One remarkable feature of MOFs with group 3 and 4 metals is that they generally can form phases containing M 6 O 8 (M = Y, Ln, An, Zr and Hf) clusters, regardless of their atomic numbers, charges and radius. This series of M 6-based MOFs is best represented by UiO series such as UiO-66 with fcu topology. [13] Under different synthetic conditions, UiO-66(M, M = An, Zr and Hf) constructed from [M 6 (μ 3-O) 4 (μ 3-OH) 4 ] clusters and linear carboxylates can be obtained, while UiO-66(M, M = Y, Ln) is assembled from Metal-organic frameworks (MOFs) based on group 3 and 4 metals are considered as the most promising MOFs for varying practical applications including water adsorption, carbon conversion, and biomedical applications. The relatively strong coordination bonds and versatile coordination modes within these MOFs endow the framework with high chemical stability, diverse structures and topologies, and interesting properties and functions. Herein, the significant progress made on this series of MOFs since 2018 is summarized and an update on the current status an...

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Keeping Superprotonic Conductivity over a Wide Temperature Region via Sulfate Hopping Sites‐Decorated Zirconium‐Oxo Clusters

Xie

Lin

et al. 2022

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Nevertheless, perfluorinated polymers usually involve complex synthesis process. Besides, they are amorphous polymers without clear structures, which make it challenging to uncover their proton transport mechanism for directionally improving the proton conducting performances. [4] Recently, crystalline porous materials such as metal-organic frameworks (MOFs) and metal-oxo clusters have been extensively investigated in the pursuit of new proton conductors. [5] In particular, porous MOFs have attracted great attention because of their diverse structures and high porosity. Besides, their proton conducting performances can be effectively improved through structural functionalization, such as decorating functionalized groups (e.g., SO 3 H, COOH, and PO 3 H 2 ) on the linkers or adding proton carriers (e.g., imidazole and sulfuric acid) into the porous channels. [6] Nevertheless, many porous MOFs are sensitive to water and easily to lose guest/ water molecules, especially under high temperature, which make a great challenge for their application under these conditions. [7] Compared with MOFs, crystalline metal-oxo clusters, especially those constructed by high valence metal ions and O-contained ligands (e.g., SO 4 2− and PO 4 2−) usually show more stable in aqueous media. [8] In addition, their hydrophilic O-rich surface can function as proton hopping sites and binding sites Metal-oxo clusters have emerged as advanced proton conductors with welldefined and tunable structures. Nevertheless, the exploitation of metal-oxo clusters with high and stable proton conductivity over a relatively wide temperature range still remains a great challenge. Herein, three sulfate groups decorated zirconium-oxo clusters (Zr 6 , Zr 18 , and Zr 70 ) as proton conductors are reported, which exhibit ultrahigh bulk proton conductivities of 1.71 × 10 −1 , 2.01 × 10 −2 , and 3.73 × 10 −2 S cm −1 under 70 °C and 98% relative humidity (RH), respectively. Remarkably, Zr 6 and Zr 70 with multiple sulfate groups as proton hopping sites show ultralow activation energies of 0.22 and 0.18 eV, respectively, and stable bulk conductivities of >10 −2 S cm −1 between 30 and 70 °C at 98% RH. Moreover, a time-dependent proton conductivity test reveals that the best performing Zr 6 can maintain high proton conductivity up to 15 h with negligible loss at 70 °C and 98% RH, representing one of the best crystalline cluster-based proton conducting materials.

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A series of zirconium-oxo cluster complexes based on arsenate or phosphonate ligands

Cited by 8 publications

References 25 publications

Atomically precise surface chemistry of zirconium and hafnium metal oxo clusters beyond carboxylate ligands

Atomically precise surface chemistry of zirconium and hafnium metal oxo clusters beyond carboxylate ligands

Metal–Organic Frameworks Based on Group 3 and 4 Metals

Keeping Superprotonic Conductivity over a Wide Temperature Region via Sulfate Hopping Sites‐Decorated Zirconium‐Oxo Clusters

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