Heterobimetallic Triple‐Stranded Helicates with Directional Benzene‐<i>o</i>‐dithiol/Catechol Ligands

Hahn, F. Ekkehardt; Offermann, Martin; Isfort, Christian Schulze; Pape, Tania; Fröhlich, Roland

doi:10.1002/anie.200801172

Cited by 65 publications

(35 citation statements)

References 52 publications

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“…27A). Mixture of the ligand, 108, Ti IV and Mo IV in a 1 : 1 : 1 ratio leads to the formation of a mixed-metal triple-stranded helicate, 109, in which the directionality of the ligands is all the same, and a racemic mixture of DD/LL was observed in solution 82 (Fig. 27B).…”

Section: Heterometallic Structuresmentioning

confidence: 99%

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Building on architectural principles for three-dimensional metallosupramolecular construction

et al. 2013

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Over the last two decades the field of metallosupramolecular self-assembly has emerged as a promising research area for the development of intricate, three-dimensional structures of increasing complexity and functionality. The advent of this area of research has strongly benefited from design principles that considered the ligand geometry and metal coordination geometry, thus opening up routes towards rationally designed classical (Archimedean or Platonic) architectures. In this tutorial review, we will focus on more recent developments in the design and synthesis of three-dimensional suprastructures which have non-classical architectures (non-Archimedean/Platonic solids) and we will explicitly address the secondary effects responsible for their formation. Three classes of metallosupramolecular assemblies will be discussed: architectures formed through the combination of a single ligand and metal, heteroleptic structures and heterometallic structures. It is hoped that our exposition may suggest how different principles employed in these three classes of structures might be combined to create even greater complexity and potential for function.

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Section: Heterometallic Structuresmentioning

confidence: 99%

“…[81][82][83] Mixing of ligand 105 with Ti IV generates a helicate, but the directionality of these complexes resulted in mixtures of isomers in solution (Fig. 27A).…”

Section: Heterometallic Structuresmentioning

confidence: 99%

Building on architectural principles for three-dimensional metallosupramolecular construction

et al. 2013

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“…Metallohelicates, which comprise two or more organic ligands wrapped around two or more metal cations, [2] are representative examples of artificial helical structures. Double‐stranded, [2–4] triple‐stranded, [5–18] and quadruple‐stranded [19–25] metallohelicates and circular metallohelicates [26] have been developed due to their structures reminiscent of the DNA double strands and their potential applications. Reymond et al developed triple‐stranded [5] and quadruple‐stranded [21] metallohelicates.…”

Section: Introductionmentioning

confidence: 99%

Calix[4]arene‐Based Triple‐Stranded Metallohelicate in Water

Morie

Sekiya

Haino

2020

Chemistry An Asian Journal

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The title complex is a triple‐stranded metallohelicate organized by the self‐assembly of 5,17‐difunctionalized calix[4]arenes and metal cations with octahedral coordination geometry. Due to hydrophilic triethylene glycol chains on the lower rim of the calix[4]arene, the metallohelicate can encapsulate cationic guests in water. NMR and UV‐vis titration experiments reveal that the metallohelicate captures a pyridinium guest with an alanine derivative to form a host‐guest complex with a host‐guest ratio of 1 : 1. CD spectroscopy confirms the bias of the P‐ and M‐helical sense of the metallohelicate by the captured guest. The metallohelicate captures two molecules of dicationic N,N’‐dimethyl‐DABCO and monocationic N‐methyl quinuclidine, exhibiting a positive allosteric effect. 1H NMR titration experiments indicate that the bound guests are in close proximately to the aromatic rings of the ligands. Molecular mechanics calculations based on the UV‐vis and NMR observations suggest that the first guest preorganizes the conformation of the metallohelicate to facilitate access of the second guest to the cavity.

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“…We assume that each asymmetric unit either contains 1/2 of a disordered lithium cation or that a lithium cation is also located on the twofold axis. We have previously described similar problems in locating the light lithium cation in X‐ray diffraction studies on dinuclear triple‐stranded helicates 10c. Each titanium atom is coordinated by six sulfur atoms in a strongly distorted octahedral fashion with calculated twist angles of Φ =33.0° (Ti1) and 39.6° (Ti2).…”

Section: Methodsmentioning

confidence: 92%

Enantiocontrolled Total Synthesis of (−)‐Mersicarpine

Iwama

Okano

Sugimoto

et al. 2013

Chemistry A European J

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A racemic synthesis of mersicarpine (1) was achieved by the Mizoroki-Heck reaction and a DIBALH-mediated reductive ring-expansion reaction. Based on a first-generation synthesis, a second-generation enantiocontrolled total synthesis of (-)-mersicarpine (1) was achieved by an 8-pot/11-step sequence in 21% overall yield from commercially available 2-ethylcyclohexanone. Subjection of a ketoester, which was prepared by an asymmetric Michael addition (according to the protocol by d'Angelo and Desmaële), and phenylhydrazine to modified Fischer indole conditions provided a six-membered tricyclic indole. Benzylic oxidation and subsequent oxime formation provided a ketoxime, which was treated with diisobutylaluminum hydride (DIBALH) to construct the characteristic azepinoindole skeleton in good yield. In the DIBALH-mediated reductive ring-expansion reaction, gradually increasing the reaction temperature and in situ-protection of the nitrogen in an oxygen-sensitive azepinoindole with a benzyloxycarbonyl (Cbz) group were crucial for the high-yielding process. With these methodologies, the short-step and efficient synthesis of (-)-mersicarpine was accomplished. Several synthetic efforts are also described.

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Heterobimetallic Triple‐Stranded Helicates with Directional Benzene‐o‐dithiol/Catechol Ligands

Cited by 65 publications

References 52 publications

Building on architectural principles for three-dimensional metallosupramolecular construction

Building on architectural principles for three-dimensional metallosupramolecular construction

Calix[4]arene‐Based Triple‐Stranded Metallohelicate in Water

Enantiocontrolled Total Synthesis of (−)‐Mersicarpine

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