Selbstaufbau eines zirkularen Doppelhelicates

Hasenknopf, Bernold; Lehn, Jean‐Maríe; Kneisel, Boris O.; Baum, Gerhard; Fenske, Dieter

doi:10.1002/ange.19961081632

Cited by 201 publications

(102 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Although this involves formation of imine bonds, it is effectively a cyclic version of the self-sorting experiment with linear helicates pioneered by Lehn and co-workers, [5] but instead of using ligand strands that sort according to the number of bidentate binding sites and overall length, 1 and 2 have the same number of binding sites and differ only by a one atom spacing of those binding sites within the strand. [14,15] Nonetheless, each ligand is able to effectively distinguish self from non-self in forming different-sized circular assemblies and the components are able to exchange in-and-out of the circular helicates in a facile manner. Dialdehydes 1 and 2 also largely self-sort according to the size of the circular helicate in their reaction with diamine 6, thereby generating Solomon link 7 and pentafoil knot 8, respectively.…”

Section: Methodsmentioning

confidence: 99%

The Self‐Sorting Behavior of Circular Helicates and Molecular Knots and Links

et al. 2014

View full text Add to dashboard Cite

We report on multicomponent self-sorting to form open circular helicates of different sizes from a primary monoamine, Fe II ions, and dialdehyde ligand strands that differ in length and structure by only two oxygen atoms. The corresponding closed circular helicates that are formed from a diamine-a molecular Solomon link and a pentafoil knotalso self-sort, but up to two of the Solomon-link-forming ligand strands can be accommodated within the pentafoil knot structure and are either incorporated or omitted depending on the stage that the components are mixed.The spontaneous segregation of molecular building blocks into discrete species within a mixture is known as selfsorting, [1] a phenomenon that helps to maintain structural control over complex dynamic systems in nature. [2] The use of orthogonal recognition elements is a convenient way to achieve sorting in artificial systems, [1,3] but other methods, [4] including subtle differences in ligand design, [5][6][7] can also be remarkably effective. A beautiful example is the classic experiment by Lehn and co-workers [5] in which a mixture of ligand strands containing two to five 2,2'-bipyridine groups spontaneously self-sort into linear double helicates, each containing two ligands with equal numbers of binding sites, in the presence of Cu I ions.We recently described the synthesis of a molecular Solomon link [8] (a doubly entwined [2]catenane [9] ) and a molecular pentafoil knot, [10] each formed through a combination of metal-ligand coordination, an anion template, and geometric restrictions. These closely related structures are derived from tetra- [8] and pentameric [10] circular helicate scaffolds, respectively, and are assembled from up to 20 common, or similar, components. Here we investigate the self-sorting behavior of both the closed molecular topologies and the open circular helicate scaffolds on which they are based (Figure 1). The study provides insights into the self-assembly processes of the individual species and reveals a subtle interplay between the driving forces and kinetic traps involved in their assembly.Despite their structural similarities (a difference of just two oxygen atoms in length), dialdehydes 1 and 2 react individually with a suitable monoamine and FeCl 2 to generate different-sized circular helicates: tetrameric [8] with 1 and pentameric [10] with 2. To investigate the self-sorting potential of the ligands, a 1:1 mixture of aldehydes 1 and 2 was allowed to react with FeCl 2 and n-hexylamine (3) in [D 6 ]DMSO at 60 8C for 18 h, followed by anion exchange through the addition of an aqueous solution of potassium hexafluorophosphate (Scheme 1). 1 H NMR spectroscopy (Figure 2 a, i) indicated the formation of both tetramer 4 and pentamer 5, the spectrum of the reaction outcome being a superimposition of the spectra from the reaction of the individual aldehydes under similar experimental conditions (Figure 2 a, ii and iii). Electrospray mass spectrometry (ESIMS) confirmed perfect self-sorting, with no detectable formation of...

show abstract

Section: Methodsmentioning

confidence: 99%

The Self‐Sorting Behavior of Circular Helicates and Molecular Knots and Links

et al. 2014

View full text Add to dashboard Cite

show abstract

“…Thus, the Cl À anion has been successfully used to assemble double-helical motifs of various molecules containing aromatic groups, with %-stacking within the helices (Hasenknopf et al, 1996(Hasenknopf et al, , 1997. Indeed, halide anions can be particularly useful for such applications because of the high exibility of their coordination (Ilioudis et al, 2000).…”

Section: Commentmentioning

confidence: 99%

4-[Bis(4-hydroxy-3,5-dimethylphenyl)methyl]pyridinium chloride and bromide

et al. 2005

View full text Add to dashboard Cite

show abstract

“…More impressive is the exclusive assembly of an enantiomeric pair of homochiral tetrahedral clusters when the ligand is racemic rather than enantiopure [Eq. (2,3)]. For a polynuclear species the term (Figure 2) shows the metal complex to be on a site with T point symmetry.…”

mentioning

confidence: 99%

“…[3] Another ligand has been shown to generate both [(FeL) 3 ] 6 and [(FeL) 4 ] 8 complexes simultaneously. [4] In addition a binuclear [(AgL a ) 2 ] 2 complex and a trinuclear [(AgL b ) 3 ] 3 complex, where L a and L b are very similar bisoxazoline ligands, have been crystallographically characterized. [5] The variety of stoichiometries observed with similar, or even identical ligands indicates that the factors discriminating such stoichiometries are rather subtle.…”

mentioning

confidence: 99%

“…A linear trisbidentate ligand that forms a trinuclear triple helix with octahedrally coordinated metals (M 3 L 3 ) [1] also generates a circular helix (M 5 L 5 ) under different conditions. [2] More recently one bis-bidentate ligand generated a mixture of three rapidly equilibrating metal complexes [(CuL) n ] n (n 1 ± 3). [3] Another ligand has been shown to generate both [(FeL) 3 ] 6 and [(FeL) 4 ] 8 complexes simultaneously.…”

mentioning

confidence: 99%

See 1 more Smart Citation