Shape‐persistent Macrocycles through Dynamic Covalent Reactions

Yu, Cao; Zhang, Wei

doi:10.1002/9781119075738.ch3

Cited by 9 publications

(9 citation statements)

References 256 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Alkyne metathesis is effective for the scalable, high-yielding synthesis of arylene ethynylene macrocycles, which was recently exploited by the Tilley group for general incorporation of PAHs into such structures . The two alkynyl groups at the termini of helicene 3 are suitably oriented to form the figure-eight macrocycle 2 (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Expanded Helicenes as Synthons for Chiral Macrocyclic Nanocarbons

et al. 2020

View full text Add to dashboard Cite

Expanded helicenes are large, structurally flexible π-frameworks that can be viewed as building blocks for more complex chiral nanocarbons. Here we report a gram-scale synthesis of an alkyne-functionalized expanded [11]helicene and its single-step transformation into two structurally and functionally distinct types of macrocyclic derivatives: (1) a figure-eight dimer via alkyne metathesis (also gram scale) and (2) two arylene-bridged expanded helicenes via Zr-mediated, formal [2+2+n] cycloadditions. The phenylene-bridged helicene displays a substantially higher enantiomerization barrier (22.1 kcal/mol) than its helicene precursor (<11.9 kcal/mol), which makes this a promising strategy to access configurationally stable expanded helicenes. In contrast, the topologically distinct figure-eight retains the configurational lability of the helicene precursor. Despite its lability in solution, this compound forms homochiral single crystals. Here, the configuration is stabilized by an intricate network of two distinct yet interconnected helical superstructures. The enantiomerization mechanisms for all new compounds were probed using density functional theory, providing insight into the flexibility of the figure-eight and guidance for future synthetic modifications in pursuit of non-racemic macrocycles.

show abstract

Section: Resultsmentioning

confidence: 99%

Expanded Helicenes as Synthons for Chiral Macrocyclic Nanocarbons

et al. 2020

View full text Add to dashboard Cite

show abstract

“…26,49,50 In the context of macrocyclization, we also must consider the t to the product geometry. 51 For example, for a shapepersistent triangular [3 + 3] macrocycle, we expect the corners to make angles of roughly 60 . 52 The potential for each folding state to t into this architecture can be approximated via its "bite" (or "bend") angle b; that is, the angle made by the points of attachment to the o-phenylene moiety.…”

Section: Synthesis Of Componentsmentioning

confidence: 99%

Macrocycles of Higher Ortho-Phenylenes: Assembly and Folding

Kinney¹,

Kirinda²,

Hartley³

2019

Preprint

View full text Add to dashboard Cite

Higher-order structure in abiotic foldamer systems represents an important but largely unrealized goal. As one approach to this challenge, covalent assembly can be used to assemble macrocycles with foldamer subunits in well-defined spatial relationships. Such systems have previously been shown to exhibit self-sorting, new folding motifs, and dynamic stereoisomerism, yet there remain important questions about the interplay between folding and macrocyclization and the effect of structural confinement on folding behavior. Here, we explore the dynamic covalent assembly of extended ortho-phenylenes (hexamer and decamer) with rod-shaped linkers. Characteristic 1H chemical shift differences between cyclic and acyclic systems can be compared with computational conformer libraries to determine the folding states of the macrocycles. We show that the bite angle provides a measure of the fit of an o-phenylene conformer within a shape-persistent macrocycle, affecting both assembly and ultimate folding behavior. For the o-phenylene hexamer, the bite angle and conformer stability work synergistically to direct assembly toward triangular [3+3] macrocycles of well-folded oligomers. For the decamer, the energetic accessibility of conformers with small bite angles allows [2+2] macrocycles to be formed as the predominant species. In these systems, the o-phenylenes are forced into unusual folding states, preferentially adopting a backbone geometry with distinct helical blocks of opposite handedness. The results show that simple restrictions can be used to direct foldamers toward increasingly complex geometries.

show abstract

“…Salphens are p-conjugated salen systemsa nd thus have advantages in terms of stability, optical properties, and reactivity, which, for instance, make them excellent catalysts and ion sen-sors. [18,[22][23][24] The reversible character of imine condensation with dynamic exchange of C=Nb onds meets the requirements for dynamic covalentr eactions, [25] which has been exploited to prepare shape-persistent 2D and 3D molecular systems of highc omplexity in high yields, such as macrocycles [26][27][28][29][30] tiered architectures, [31] capsules, [32] and molecular cages. [16][17][18] Salphen-type macrocycles have attractedaparticular interesti nt he field of supramolecular chemistry,o wing to their ability to self-assemble into organized stacks.…”

Section: Introductionmentioning

confidence: 99%

“…[7][8][9][10][19][20][21] In particular,t he aggregation behavior of multinuclear Zn II salphen complexes is strongly enhanced owing to their unusual oligomeric (ZnÀO) n coordination motifs, ap eculiar property that has been exploited for the construction of self-assembled nanostructures of very high stability. [18,[22][23][24] The reversible character of imine condensation with dynamic exchange of C=Nb onds meets the requirements for dynamic covalentr eactions, [25] which has been exploited to prepare shape-persistent 2D and 3D molecular systems of highc omplexity in high yields, such as macrocycles [26][27][28][29][30] tiered architectures, [31] capsules, [32] and molecular cages. [33][34][35][36][37][38] Oneo ft he main synthetic challenges is to obtain selectively one type of macrocycle of ag iven size in good yield.…”

Section: Introductionmentioning

confidence: 99%

“…The reversible character of imine condensation with dynamic exchange of C=N bonds meets the requirements for dynamic covalent reactions, which has been exploited to prepare shape‐persistent 2D and 3D molecular systems of high complexity in high yields, such as macrocycles tiered architectures, capsules, and molecular cages . One of the main synthetic challenges is to obtain selectively one type of macrocycle of a given size in good yield.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Constrained and “Inverted” [3+3] Salphen Macrocycle with an ortho‐Phenylethynyl Substitution Pattern

Urbani

Torres

2020

Chemistry A European J

View full text Add to dashboard Cite

A[ 3 + +3] Schiff-base salphen macrocycle (7a)w as synthesized by imine condensation between ortho-phenylenediamine and ortho-phenylethynyl-bridged bis(5-salicylaldehyde) precursors. The triangular-shaped macrocycle 7a has an onclassical (or "inverted") design in whicht he N 2 O 2 coordination pockets are located at the sides insteado ft he corners. Compound 7a could be synthesized in ar easonably good yield (64 %) considering the steric constraints imposed by the ortho substitution pattern. Subsequent zinc metalation afforded the corresponding Zn metallomacrocycle 7b. Spectroscopic experiments evidencedw eak (7a)t os trong (7b)s elf-aggregation behavior in solution. Their ability to self-organize at the supramolecular level was further studied in the solid state by AFM and TEM, which revealed the formation of largeb undles of fibers with lengths of severalm icrometers and widths of nanometers.[a] Dr.M.U rbani, Prof. T. Torres

show abstract

Shape‐persistent Macrocycles through Dynamic Covalent Reactions

Cited by 9 publications

References 256 publications

Expanded Helicenes as Synthons for Chiral Macrocyclic Nanocarbons

Expanded Helicenes as Synthons for Chiral Macrocyclic Nanocarbons

Macrocycles of Higher Ortho-Phenylenes: Assembly and Folding

A Constrained and “Inverted” [3+3] Salphen Macrocycle with an ortho‐Phenylethynyl Substitution Pattern

Contact Info

Product

Resources

About