A bipyridine-ligated zinc(II) complex with bridging flavonolate ligation: synthesis, characterization, and visible-light-induced CO release reactivity

作者：Sorenson Shayne; Popova Marina; Arif Atta M; Berreau Lisa M^*

来源：Acta Crystallographica Section C-Structural Chemistry, 2017, 73(9): 703-+.

DOI：10.1107/S2053229617011366

• zinc
• flavonol
• conductivity
• carbon monoxide
• nuclearity
• crystal structure
• CO release
• synthetic models

Metal-flavonolate compounds are of significant current interest as synthetic models for quercetinase enzymes and as bioactive compounds of importance to human health. Zinc-3-hydroxyflavonolate compounds, including those of quercetin, kampferol, and morin, generally exhibit bidentate coordination to a single Zn-II center. The bipyridine-ligated zinc-flavonolate compound reported herein, namely bis(mu-4-oxo-2-phenyl-4H-chromen-3-olato)-kappa O-3(3):O-3,O-4;kappa O-3(3),O-4:O-3 bis[( 2,2'-bipyridine-kappa N-2,N')zinc(II)] bis(perchlorate), {[Zn-2(C15H9O3)(2)(C(10)H8N2)(2)](ClO4)(2)}(n), (1), provides an unusual example of bridging 3-hydroxyflavonolate ligation in a dinuclear metal complex. The symmetry-related Zn-II centers of (1) exhibit a distorted octahedral geometry, with weak coordination of a perchlorate anion trans to the bridging deprotonated O atom of the flavonolate ligand. Variable-concentration conductivity measurements provide evidence that, when (1) is dissolved in CH3CN, the complex dissociates into monomers. H-1 NMR resonances for (1) dissolved in d(6)-DMSO were assigned via HMQC to the H atoms of the flavonolate and bipyridine ligands. In CH3CN, (1) undergoes quantitative visible-light-induced CO release with a quantum yield [0.004 (1)] similar to that exhibited by other mononuclear zinc-3-hydroxyflavonolate complexes. Mass spectroscopic identification of the [(bpy)(2)Zn(O-benzoylsalicylate)](+) ion provides evidence of CO release from the flavonol and of ligand exchange at the Zn-II center.

• 出版日期2017-9