7-membered-ring effect on fluorescence quantum yield: does metal-complexation-induced twisting-inhibition of an amino GFP chromophore derivative enhance fluorescence?

Hao Wei Ke, Kuangsen Sung

研究成果: Article同行評審

1 引文 斯高帕斯(Scopus)

摘要

To investigate two aspects, namely, (1) the 7-membered-ring effect on fluorescence quantum yield and (2) whether metal-complexation-induced twisting-inhibition of an amino green fluorescent protein (GFP) chromophore derivative is bound to enhance fluorescence, a novel GFP-chromophore-based triamine ligand, (Z)-o-PABDI, is designed and synthesized. Before complexation with metal ions, the S1 excited state of (Z)-o-PABDI undergoes τ-torsion relaxation (Z/E photoisomerization) with a Z/E photoisomerization quantum yield of 0.28, forming both ground-state (Z)- and (E)-o-PABDI isomers. Since (E)-o-PABDI is less stable than (Z)-o-PABDI, it is thermo-isomerized back to (Z)-o-PABDI at room temperature in acetonitrile with a first-order rate constant of (1.366 ± 0.082) × 10−6 s−1. After complexation with a Zn2+ ion, (Z)-o-PABDI as a tridentate ligand forms a 1 : 1 complex with the Zn2+ ion in acetonitrile and in the solid state, resulting in complete inhibition of the φ-torsion and τ-torsion relaxations, which does not enhance fluorescence but causes fluorescence quenching. (Z)-o-PABDI also forms complexes with other first-row transition metal ions Mn2+, Fe3+, Co2+, Ni2+ and Cu2+, generating almost the same fluorescence quenching effect. By comparison with the 2/Zn2+ complex, in which a 6-membered ring of Zn2+-complexation enhances fluorescence significantly (a positive 6-membered-ring effect on fluorescence quantum yield), we find that the flexible 7-membered rings of the (Z)-o-PABDI/Mn+ complexes trigger their S1 excited states to relax through internal conversion at a rate much faster than fluorescence (a negative 7-membered-ring effect on fluorescence quantum yield), leading to fluorescence quenching regardless of the type of transition metal that complexes with (Z)-o-PABDI.

原文English
頁(從 - 到)14627-14634
頁數8
期刊Physical Chemistry Chemical Physics
25
發行號20
DOIs
出版狀態Published - 2023 4月 25

All Science Journal Classification (ASJC) codes

  • 一般物理與天文學
  • 物理與理論化學

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