Novel Three-Dimensional Organic–Inorganic Heterometallic Hybrid Built by Sandwich-Type Tetra-Mn-Substituted Germanotungstates through Mixed 3d and 4f Metal Linkers

Abstract

The reaction of trivacant Keegin germanotungstate [A-α-GeW9O34]10– with Mn2+ and Ce4+ cations in the presence of oxalate ligand under hydrothermal conditions led to the isolation of a novel organic–inorganic hybrid 3d–4f heterometallic germanotungstate K4Na4[Ce2(ox)3(H2O)2]2{[Mn(H2O)3]2[Mn4(GeW9O34)2(H2O)2]·14H2O (1) (ox = oxalate), which has been characterized by elemental analysis, IR spectroscopy, thermogravimetric (TG) analysis, and single-crystal X-ray crystallography. Interestingly, each tetra-MnII-substituted sandwich-type unit acts as 14-dentate ligands to link eight Ce3+ centers and six Mn2+ centers further into a three-dimensional (3D) architecture. The 3D structure can be considered as two parts: one is the two-dimensional layer formed by sandwich-type [Mn4(H2O)2(GeW9O34)2]12– fragments and Mn2+ linkers; the other layer is constructed from Ce3+ cations and oxalate bridges, and the two layers are combined together alternately through W–O–Ce–O–W linkers, resulting in the 3D framework. Notably, 1 exhibits the first 3d–4f 3D organic–inorganic hybrid framework constructed by sandwich-type TM-substituted polyoxoanions and mixed 3d and 4f metal linkers in POM chemistry.

Synergistic effect of sandwich polyoxometalates and copper–imidazole complexes for enhancing the peroxidase-like activity

“…31,32 In view of diverse POMs, 33 sandwich-type POMs are usually synthesized in weak acidic solutions, which may show synergistic effects with combined transitional metal ions and intriguing redox properties. [34][35][36][37][38][39][40] Wang et al recently reported tetranuclear zirconiumsubstituted polyoxometalates with peroxidase-like activity, which indicates that the active catalytic species are ascribed to the unique structural feature of sandwiched {Zr 4 } clusters but not the lacunary polyoxometalate anions themselves or the independent Zr ions. 41 However, the reaction time of TMB oxidation in Wang's work was 90 min, which still did not fulll the stringent requirement of bio-detectors, requiring a fast response.…”

Syntheses and Characterizations of Two New Octamolybdate-Based Polyoxometalates Decorated by Isoquinoline Ligands

“…Design and synthesize of organic-inorganic hybrids have attracted a great deal of interest in the chemistry and materials fields, not only because of their fascinating topology and intriguing architectures, [1][2][3][4] but also due to their potential applications in magnetism, [5][6][7][8][9] luminescence, [10][11][12][13][14][15][16] ion exchange, [17,18] and catalysis [19] etc. Among them, octamolybdate [Mo 8 O 26 ] 4-based polyoxometalates (POMs) have been extensively studied for their structural diversity and potential coordination capability in building high dimensional frameworks.…”

Roles of Organic Fragments in Redirecting Crystal/Molecular Structures of Inorganic–Organic Hybrids Based on Lacunary Keggin-Type Polyoxometalates

“…Because of high affinity of RE cation linkers to the anionic surface of polyanions, their utilization in synthesis is challenging and almost leads to precipitation [ 180 , 181 ]. By introducing O-donor ligands to the reaction medium Zhao et al [ 182 ] successfully established the 3D K 4 Na 4 [Ce 2 (ox) 3 (H 2 O) 2 ] 2 {[Mn(H 2 O) 3 ] 2 [Mn 4 (GeW 9 O 34 ) 2 (H 2 O) 2 ]·14H 2 O hybrid with Weakley sandwich-type structure via tetra Mn II belt and 3d-4f connector. Zhang and co-workers prepared two types of RESP hybrids based on phosphotungstates via oxalate linkages.…”