The Gigantic {Ni₃₆Gd₁₀₂} Hexagon: A Sulfate-Templated “Star-of-David” for Photocatalytic CO₂ Reduction and Magnetic Cooling

Abstract

Gigantic coordination molecules assembled from a large number of metal ions and organic ligands are structurally and functionally challenging to characterize. Here we show that a heterometallic cluster [Ni36Gd102(OH)132­(mmt)18­(dmpa)18­(H2dmpa)24­(CH3COO)84­(SO4)18­(NO3)18­(H2O)30]·Br6(NO3)6·(H2O) x ·(CH3OH) y , (1, x ≈ 130, y ≈ 60), shaped like a “Star of David”, can be synthesized using a “mixed-ligand” and “sulfate-template” strategy. In terms of metal nuclearity number, 1 is the second largest 3d–4f cluster to date. In the solid state, 1 is porous after removing the lattice guests. The N2 adsoption experiment reveals that the BET and Langmuir surface areas are 299.8 and 412.0 cm2 g–1, respectively. CO2 adsorption at 298 K gives the amount of 45 cm3 g–1 for 1. More importantly, 1 is soluble in common organic solvents and exhibits high solution stability revealed by high resolution MALDI-TOF mass spectroscopy, small-angle X-ray scattering (SAXS), and low-dose transmission electron microscopy. The solubility and the potential open metal sites owing to the labile coordinating components prompted us to investigate the photocatalytic properties of 1, which displays high selectivity and efficiency for reduction of CO2 to CO with turnover number and turnover frequency of 29700 and 1.2 s–1, respectively. These values are higher than most catalysts working under the same conditions, presumably due to the strong Ni–CO2 binding effect. In addition, the large percentage of Gd­(III) in 1 leads to a large magnetic entropy change (41.3 J·kg–1·K–1) at 2.0 K for ΔH = 7 T.

Photocatalytic Carbon Dioxide Reduction Using Nickel Complexes as Catalysts

“…[35] The (16), in which Hmmt (2mercapto-5-methyl-1,3,4-thiadiazide; Figure 9) binds to Ni centers in a deprotonated form as a bridging ligand and H 3 dmpa (2,2-dimethylol propionic acid; Figure 9) acts as hard Odonating bridging ligand, as a catalyst for photocatalytic CO 2 reduction. [36] This gigantic hexagonal cluster 16 (see Figure 10 depicting the crystal structure [36] ) shows a high reactivity in photocatalytic CO 2 reduction in DMF/H 2 O (4 : 1, v/v) at 25°C to produce CO in TON of 29,700 (10 h) and TOF of 1.2 s À 1 with 90.2 % selectivity over H 2 evolution in the presence of TEOA as a reductant and [Ru(phen) 3 ](PF 6 ) 2 as a PS under visible-light irradiation. [36] A Ni(II) center has been proposed to act as an active site for the reaction, although it is not clear which Ni center(s) are responsible for the reaction.…”

Multifunctional Melamine Foam Assisted Lead Halide Perovskites for Highly Efficient and Long‐Term Photocatalytic CO2 Reduction Under Pure Water

“…[ 1 ] The massive consumption of fossil fuels could accelerate carbon dioxide (CO 2 ) emission, causing the global energy shortage and severe environmental concerns such as greenhouse effect responsible for global warming. [ 2–5 ] Inspired by natural photosynthesis in green plants, the utilization of solar‐driven photocatalytic CO 2 reduction with water (H 2 O) as proton source to yield chemical fuels is one of the most promising strategies to solve the aforementioned issues. [ 6–8 ] Therefore, development of highly efficient catalysts with predominant optoelectronic performance is an essential effort to construct preeminent artificial photocatalysis system.…”

A Giant 3d‐4f Polyoxometalate Super‐Tetrahedron with High Proton Conductivity

“…[ 1–11 ] A particularly fascinating area in this field is the high‐nuclearity heterometallic 3d‐4f clusters because of their interesting properties arising from the interactions of 3d and 4f metal ions. [ 8–16 ] Due to involving a large number of molecules and the variable coordination geometry of lanthanide ions, the assembly of high‐nuclearity 3d‐4f clusters is a challenging topic. Until now, several gigantic heterometallic 3d‐4f clusters have been obtained under the protection of organic ligands.…”

“…Until now, several gigantic heterometallic 3d‐4f clusters have been obtained under the protection of organic ligands. [ 9–15 ] Although organic ligand can regulated the final cluster structures, the relatively low structural and thermal stability of the clusters may prevent further related property studies. In comparison, the inorganic anions with multisite coordination geometry can obviously improve the stability.…”