Dynamic Helicity Inversion by Achiral Anion Stimulus in Synthetic Labile Cobalt(II) Complex

Yoshida, Kana; Sugimoto, Hideki; Tsukube, Hiroshi

doi:10.1021/ja049130o

Cited by 96 publications

(46 citation statements)

References 35 publications

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“…These include helical polymers, [1] foldamers, [2] and helical metalc omplexes, [3] whicha re in dynamic equilibrium between the rightand left-handed forms.S ome of them can undergo dynamic helicity inversion upon stimulation by light,h eat, redoxr eaction, pH change,b inding with inorganic or organic species, etc. [7] We have recently reported the dynamic helicityc ontrol of a trinuclearh elical nickel(II) metallocryptand [LNi 3 ]a nd tuning of its helicityinversion rates. Amongt hem, binding with organic species is particularly versatile, because av ariety of chiral and achiral organic species can be used as as timulus to achieve the responsive functions.…”

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confidence: 99%

Ligand Exchange Strategy for Tuning of Helicity Inversion Speeds of Dynamic Helical Tri(saloph) Metallocryptands

Sakata

Chiba

Miyashita

et al. 2019

Chemistry A European J

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What is the most significant result of this study?We have proposed an ew strategy,al igand exchange strategy,t o control the response speeds of the helicity induction and inversion of helical complexes. Whereas there have already been an umber of reports on responsive helicity induction and inversion, methods to control the response speeds have not been established. In this study,w ef ocused on the reactivity of saloph-cobalt(III) complexes, which allows the exchange of the axial amine ligands on the timescale of several tens of minutes. We can control the response speeds by using different combinations of achiral and/or chiral amines as the initial and entering ligands.

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confidence: 99%

Ligand Exchange Strategy for Tuning of Helicity Inversion Speeds of Dynamic Helical Tri(saloph) Metallocryptands

Sakata

Chiba

Miyashita

et al. 2019

Chemistry A European J

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“…When a racemic Co(II) complex produced with achiral peptide ligands was mixed with a chiral Λ Co(II) analog of the Fe(II) complex, chirality amplification around Co(II) center and in achiral peptide helices were observed via chirality transfer from chiral peptide chains to metal center and to achiral peptide chains. Miyake et al demonstrated that the labile Co(II) complex with a chiral tetradentate ligand containing amide linkages acted as a helicity inversion unit in response to achiral NO3 − anion ( Figure 15) [74,75]. In a solid complex prepared by mixing the chiral ligand and Co(ClO4)2· 6H2O, the Co(II) complex formed the Λ cis-α structure, in which both coordinating nitrogen atoms adopted the (S) configuration.…”

Section: Dynamic Production and Inversion Of Supramolecular Chiralitymentioning

confidence: 99%

Supramolecular Chirality in Dynamic Coordination Chemistry

Miyake

2014

Symmetry

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Labile metal complexes have a useful coordination bond; which is weaker than a covalent C-C bond and is reversibly and dynamically formed and dissociated. Such labile metal complexes also can be used to construct chiral shapes and offer dynamic conversion of chiral molecular shapes in response to external stimuli. This review provides recent examples of chirality induction and describes the dynamic conversion systems produced by chiral metal complexes including labile metal centers, most of which respond to external stimuli by exhibiting sophisticated conversion phenomena.

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“…In contrast, binding of one bidentate NO 3 ¹ anion induces formation of a ¦ isomer as unambiguously characterized by single-crystal X-ray diffraction and CD spectroscopy. 48 This system was further developed to realize peptide helix inversion triggered by an NO 3 ¹ anion. They synthesized a peptidemetal conjugate in which the aforementioned Co helical structures (Figure 6).…”

Section: ç Anion-responsive Metallopeptidesmentioning

confidence: 99%

Stimuli-responsive Synthetic Metallopeptides

Tashiro

Shionoya

2013

Chemistry Letters

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Inspired by vital roles of metal ions as structure-stabilizing and regulating factors in biological systems, a great number of synthetic metallopeptides have been developed. This review focuses on metal-mediated stabilization and stimuli-responsive regulation of their secondary and higher-order structures by taking advantage of the characteristics of metal ions such as Lewis acidity, ligand-exchange ability, and redox properties. Ç IntroductionIn metal-including biomolecules such as metalloproteins or enzymes in living systems, metal ions play vital roles in molecular recognition, catalytic reaction, transportation, electron transfer, and structure stabilization or regulation.1 Focusing on a few examples of metal-mediated formation of higher-order structures of proteins, a typical example is zinc-finger proteins, which are composed of multiple finger units containing one Zn II ion bound by four coordinating side chains of His and/or Cys residues. The Zn II ions are well-known to stabilize the whole ternary structures and essential for DNA binding.2 In other cases, several metal ions such as Zn II , Cu II , and Fe III are considered a trigger for protein aggregations through interactions with some protein domains as seen in several brain disorders such as Alzheimer's disease and Parkinson's disease, 3 in which metal ions serve as inducers of protein folding or aggregation. On the other hand, metal ions in some proteins can regulate their higherorder structures through response to several stimuli, and the structural transformation is involved in protein functions. Hemoglobin is a typical example of such proteins, 4 that is a tetrameric protein in which O 2 trapping at the Fe II center of one heme unit induces the whole conformation change (T ¼ R transition) to achieve cooperative binding of molecular oxygens. One way to understand and further utilize such protein natures is a synthetic approach to stimuli-responsive mechanisms inspired by natural metalloproteins.For this purpose, design-based incorporation of metal binding sites into peptide structures has been extensively conducted. Synthetic peptides developed so far can be categorized as two types: (i) natural ¡-peptides possessing an optional sequence that can bind to metal ions through their coordinating functionalities of the residues or (ii) unnatural peptides containing synthetic amino acid residues whose side and/or main chains bind to metal ions. So far, many types of synthetic peptides have been reported based on both strategies, and the stabilization of secondary and higher-order structures of their metallopeptides has been demonstrated. Moreover, the metalmediated regulation of peptide structures has been recently studied based on the characteristics of metal ions such as Lewis acidity, ligand-exchange ability, and redox properties (Figure 1). This review describes the design outline of metallopeptides and then metal-mediated stabilization of ¡-helix and ¢-sheet structures taking a few basic examples of stimuli-responsive folding. The structu...

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Dynamic Helicity Inversion by Achiral Anion Stimulus in Synthetic Labile Cobalt(II) Complex

Abstract: The helical chirality of a Co(II) complex with a chiral tetradentate ligand is completely inverted from Lambda to Delta by the addition of achiral NO3- anion as an external stimulus.

Cited by 96 publications

References 35 publications

Ligand Exchange Strategy for Tuning of Helicity Inversion Speeds of Dynamic Helical Tri(saloph) Metallocryptands

Ligand Exchange Strategy for Tuning of Helicity Inversion Speeds of Dynamic Helical Tri(saloph) Metallocryptands

Supramolecular Chirality in Dynamic Coordination Chemistry

Stimuli-responsive Synthetic Metallopeptides

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