A Blue Zinc Complex of a Dioxobilin‐Type Pink Chlorophyll Catabolite Exhibiting Bright Chelation‐Enhanced Red Fluorescence. Issue 20 (2nd May 2021)

• Record Type: Journal Article
• Authors: Li, Chengjie; Podewitz, Maren; Kräutler, Bernhard
• Is Part Of: European journal of inorganic chemistry. Issue 20(2021)
• Page Start: 1904
• Page End: 1912
• Publication Date: 2021-05-02
• Subjects: Luminescence -- Phyllobilin -- Pigments -- Tetrapyrroles -- Transition metals -- Zinc; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.202100206
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: In senescent fall leaves and in ripening fruit, colorless phyllobilins (PBs) accumulate from breakdown of chlorophyll, from which yellow PBs (phylloxanthobilins) and pink colored PBs (phylloroseobilins) arise in some leaves. The first described PBs were formyloxobilin‐type PBs, but dioxobilin‐type PBs also occur naturally. Here we report the synthesis and characterization of the blue Zn(II) complex of a dioxobilin‐type pink PB, which chelates a Zn(II) ion fast and tightly in an effectively tridentate manner. The optically active Zn complex featured bright chelation enhanced red fluorescence and exhibited strikingly differing spectral properties in methanol and in acetonitrile. Computational studies based on DFT‐calculations gave detailed insights into low energy structures of the Zn complex in both solvents and provided support for the proposed role of solvent in the coordination sphere of the bound Zn(II) ion. Abstract : A pink phyllobilin from breakdown of chlorophyll in fall leaves is effectively a tridentate ligand for a zinc(II) ion, furnishing an optically active blue zinc(II) complex that emits bright chelation‐enhanced red fluorescence. Computational studies based on DFT‐calculations have helped to characterize the structures of this complex in methanol and acetonitrile solutions and to rationalize its strikingly different spectral properties in these two solvents.