Octanuclear Ln(III)-Based Clusters Assembled by a Polydentate Schiff Base Ligand and a β-Diketone Co-Ligand: Efficient Conversion of CO₂ to Cyclic Carbonates and Large Magnetocaloric Effect

Abstract

A series of new Ln8 clusters [Ln8(acac)4(HL)4(L)2(μ3-O)4(C2H5O)4]·2C2H5OH·2CH2Cl2 (Ln(III) = Gd (1), Dy (2), and Ho (3); Hacac = acetylacetone and H2L = 2-hydroxy-benzoic acid (5-hydroxymethyl-furan-2-ylmethylene)-hydrazide) have been designed and constructed using a multiple coordination site Schiff base ligand (H2L) as well as a β-diketonate auxiliary ligand. The structures, magnetic properties, and catalytic performance of clusters 1–3 have been studied. X-ray crystallography data revealed that clusters 1–3 possess similar structures with two chair-form Ln4 cores bridged by four μ3-O atoms. Clusters 1–3 display extensive and high solvent stability. Magnetic analysis exhibits that cluster 1 possesses a comparably large magnetocaloric effect (−ΔS m = 33.06 J kg–1 K–1 at 2.0 K and 7.0 T). AC susceptibility measurement suggests that cluster 2 exhibits single-molecule magnet behavior under zero-field conditions. What’s more, all clusters can effectively convert CO2 with epoxides. The highest yield is 98% at 70 °C 0.1 MPa catalyzed by 1. In addition, cluster 1 can be reused three times with a negligible loss of catalytic activity.

Two novel Ln8 clusters bridged by CO32− effectively convert CO2 into oxazolidinones and cyclic carbonates

“…When 3.5 mol% and 4.0 mol% TBAB alone were used to catalyze the conversion of CO 2 at 80 °C under 1 bar for 12 h, the yields rose to 42% and 46%, respectively (Table 4, entries 13 and 14). When TBAB was replaced by different co-catalysts (Table 4, entries [15][16][17][18], the yield was between 29% and 31%, which further suggests that TBAB is the optimal co-catalyst for CO 2 conversion. In addition, the equivalent concentrations of Nd salts such as Nd (NO 3 ) 3 •6H 2 O, Nd(CH 3 COO) 3 •6H 2 O and NdCl 3 •6H 2 O acting as catalysts could not catalyze the cycloaddition reaction under the same conditions (Table 4, entries [19][20][21].…”

“…6 It is clear that the transformation of CO 2 into high value-added chemicals is one of the most effective and important routes for carbon capture and use, [7][8][9][10][11][12][13] and is consistent with the development concepts of green chemistry. 14 In view of this, quite a lot of effort has been focused on converting CO 2 into high valueadded products, such as cyclic carbonates, [15][16][17] oxazolidinone, 18 quinazoline, 19 and propargylic amines. 20 Oxazolidinone compounds, for example, are important pharmaceutical intermediates used in the synthesis of many antimicrobial drugs, and they show effective biological activi-ties by interacting with a variety of enzymes and receptors in organisms.…”

The Catalytic Coupling of CO2 and Glycidol toward Glycerol Carbonate

“…Among transition and post transition metals (Figure , in blue), examples with Ti-, , Cr-, , Co-, − Ga-, Y-, , Ru-, Rh-, Pd-, Cd-, , and In-based catalysts have been documented. Examples of catalysts featuring lanthanides, such as La, − Ce, − Nd, , Eu, − Gd, , Tb, − Dy, , Ho, Er, Yb, ,, and Lu, have also been reported. Apart from titanium and chromium, all these metals have a low to medium global availability .…”

Two Series of Tetranuclear Ln(III)-Based Clusters: Structures, Magnetic Behaviors, and Efficient Cycloaddition of CO2 to Oxazolidinones

“…It is becoming increasingly clear that the excessive emission of CO 2 caused by ocean acidification is becoming a major priority. − Fruitful efforts have turned toward converting nontoxic and renewable CO 2 into value-added fine chemicals. − Given that CO 2 is the kinetic inertness and thermodynamic stability, this way in itself is greatly challenging. CO 2 is an important building block molecule to the synthesis of many important classes of compounds. − The oxazolidinones, five-membered heterocyclic compounds, have been widely studied because of the application in antibiotics with the activity against Gram-positive bacteria.…”