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To obtain insights into the role of the carboxylate group of Glu73 in the active site of quercetin 2,4-dioxygenase (2,4-QD), the copper(II) complexes [CuIIL n(AcO)] [ 1 (L n = L1), 2 (L n = L2), 3 (L n = L3), and 4 (L n = L4)] supported by a series of carboxylate-containing ligands [ L1H = 2-{[bis(pyridin-2-ylmethyl)amino]methyl}benzoic acid; L2H = 3-{[bis(pyridin-2-ylmethyl)amino]methyl}benzoic acid,; L3H = 2-({bis[2-(pyridin-2-yl)ethyl]amino}methyl)benzoic acid; L4H = 3-({bis[2-(pyridin-2-yl)ethyl]amino}methyl)benzoic acid] as well as the ternary CuII flavonolate (fla-) complexes [CuIIL n(fla)] [ 5 (L n = L1), 6 (L n = L2), 7 (L n = L3), and 8 (L n = L4)] were synthesized and characterized as structural and functional models for the active site of 2,4-QD. The ternary complexes [CuIIL n(fla)] showed different reactivities in the dioxygenation of bound flavonolate to benzoic acid, salicylic acid, and N, N-dimethylbenzamide at 75-90 °C (single-turnover reaction) in the order 5 >> 7 > 8 ≈ 6. A similar reactivity tendency was found in the catalytic dioxygenation of the substrate flavonol (multiturnover reaction) by the binary complexes. The different reactivities of the copper complexes could be attributed to the different Lewis acidities of the copper(II) ions induced by the different coordination environments of the ligands. The results will provide important insights into the pivotal catalytic role of the carboxylate group of Glu73 in 2,4-QD. [ABSTRACT FROM AUTHOR]

The cover picture shows dioxygen activation by CuII complexes supported by carboxylate‐containing ligands as structural and functional models of quercetin 2,4‐dioxygenase (2,4‐QD), highlighting the role of the carboxylate group in the structure and reactivity. The green fields, the blue sky, and the tree in the background symbolize molecular oxygen as a green and environmentally benign oxidant. Details are discussed in the article by Y.‐J. Sun, S. Itoh et al. on page 1845 ff (DOI: 10.1002/ejic.201601371). For more on the story behind the cover research, see the Cover Profile (DOI: 10.1002/ejic.201700245). [ABSTRACT FROM AUTHOR]

New asymmetric tetra-carboxylates ligand, 2,2′-((6-chloro-1,3,5-triazine-2,4-diyl)bis(azanediyl))diterephthalic acid (H 4 L 1 ) and hexa-carboxylates ligand, 2,2′,2″-((1,3,5-triazine-2,4,6-triyl)(azanediyl))-triterephthalic acid (H 6 L 2 ), were designed and used for the assemble reactions with Cd 2+ ions. [Cd 2 (L 1 )(H 2 O) 2 ]·2.5DMSO·2H 2 O ( 1 ) and (Me 2 NH 2 ) 9 (H 3 O) 2 [Cd 2 Cl 3 (L 2 ) 2 ]·5H 2 O ( 2 ) have been synthesized and structurally characterized. Single crystal X-ray analysis show that compound 1 bears a 2D neutral (4, 8)-net based on 3-connected {Cd 2 } nodes and 3-connected spacers. 2 is the first bilayer MOFs pillared by monatomic Cl linker and its structure is built of 4-connected single metal nodes and 3-connected spacers. The topology of the resulted (3, 4)-connected anionic framework could be described as (6 3 )(6 6 ) (Schläfli symbol). N 2 sorption isotherm of 2 shows typical type I behavior with BET surface area of 599 m 2 g −1 and a micropore volume of 0.2345 cm 3 g −1 . Luminescent analysis indicates both compounds exhibit linker-localized emission. Furthermore, infrared (IR), thermogravimetric analyses (TGA) properties of the compounds were also investigated. [ABSTRACT FROM AUTHOR]