Intramolecular Versus Intermolecular Induction of Helical Handedness in Pyridinedicarboxamide Oligomers

Maurizot, Victor; Dolain, Christel; Huc, Ivan

doi:10.1002/ejoc.200400641

Cited by 64 publications

(35 citation statements)

References 40 publications

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“…Evidence for this was provided by the crystal structure of heptameric pyridinecarboxamide oligomer 9, which constitutes the central sequence of undecamer 3. In contrast to all other crystal structures that we obtained for pyridine oligomers, [4,11,26] the structure of 9 ( Figure 5) shows a methanol molecule completely included in the helix hollow. The methanol oxygen atom is doubly hydrogen bonded to the central 2,6-pyridinedicarboxamide unit, but it statistically occupies two positions slightly above or slightly below the pyridine plane, which leads to some crystal disorder.…”

Section: Synthesiscontrasting

confidence: 64%

“…The syntheses appear to be relatively short because they involve previously described precursors that nevertheless require several steps for their preparation. Thus, quinoline dimer acid chloride 4 [25] was coupled to dimeric pyridine amine 5 [11] to give tetrameric intermediate 6 that constitutes the conical ends of a capsule (yield 80 %). The ester terminal group of this tetramer was saponified (yield 85 %) and the corresponding acid was coupled to an excess of 2,6-diaminopyridine to provide an unstable pentamer amine intermediate which was again treated with 7 to afford 2 (yield 18 %).…”

Section: Synthesismentioning

confidence: 99%

“…[2,3,11] This paper deals with the concept that the two ends of a helix hollow may be capped so as to define a confined space in which guests can be completely secluded from the surrounding medium (Scheme 1). The binding and release of the guests consequently imply a conformational change of the host to temporarily create a passage to and from the binding site.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Encapsulation of Small Polar Guests in Molecular Apple Peels

Garric

Léger

Huc

2007

Chemistry A European J

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Three aromatic oligoamides have been prepared that have alternating 1,6-diaminopyridine and 1,6-pyridinedicarboxylic acid units at the center of the sequence and two 8-amino-2-quinolinecarboxylic acid units at each extremity. The three oligomers differ in the number--3, 5, or 7-of pyridine units in the sequence. They were designed to adopt helically folded conformations in solution and in the solid state. The sequence of monomers was chosen so that the diameter of the helix is larger in the center than at each extremity, and hence they resemble helically wrapped apple peels. According to modeling studies, the pyridine units were expected to define a polar hollow within the helix that is large enough to accommodate small polar guests, whereas the quinoline units at each end of the oligomeric sequences were expected to completely cap the hollow and transform the helix cavities into a closed shell that may act as a capsule. Crystallographic studies demonstrate that the oligomers do fold into helices that define a cavity isolated from the surrounding medium in the solid state. Depending on the number of pyridine rings, one or two water molecules are bound within the capsules. The crystal structure of a capsule fragment shows that MeOH can also be hosted by the largest oligomer. Solution NMR studies confirm that binding of water also occurs in solution with the same stoichiometry as observed in the solid state. The capsules have distinct signals depending on whether they are empty, half-full, or full, and these species are in slow exchange on the NMR timescale at low temperature. Indeed, the binding and release of water molecules requires a significant conformational distortion of the helix that slows down these processes. The addition of small polar molecules such as methanol, hydrazine, hydrogen peroxide, or formic acid to the largest capsule leads to the observation of new sets of NMR signals of the capsules that were assigned to complexes with these guests. However, water appears to be the preferred guest.

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Section: Synthesiscontrasting

confidence: 64%

Section: Synthesismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Encapsulation of Small Polar Guests in Molecular Apple Peels

Garric

Léger

Huc

2007

Chemistry A European J

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“…24,28,29,47,51,77,[79][80][81][82][83][84][85][86] These helical models are important to understand chiral interaction originating in termini of a biological helical backbone, as well as to estimate the significance of the terminal moiety in the determination of a one-handed helix sense. [5][6][7][8][9][10][11][12][13] From the viewpoint, the present sequence designed with N-terminal Gly and achiral -amino acids can be regarded as another model to approach the above issues in protein-mimicking backbones.…”

Section: Discussionmentioning

confidence: 99%

Chiral interaction in Gly‐capped N‐terminal motif of 3₁₀‐helix and domino‐type induction in helix sense

Ousaka¹,

Inai²,

Okabe³

2006

Biopolymers

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Chiral interaction of helical peptide with chiral molecule, and concomitant induction in its helix sense have been demonstrated in optically inactive nonapeptide (1) possessing Gly at its N-terminus: H-Gly-(Delta(Z)Phe-Aib)(4)-OCH(3) (1: Delta(Z)Phe = Z-dehydrophenylalanine; Aib = alpha-aminoisobutyric acid). Spectroscopic measurements [mainly nuclear magnetic resonance (NMR) and circular diochroism (CD)] as well as theoretical simulation have been carried out for that purpose. Peptide 1 in the 3(10)-helix tends to adopt preferentially a right-handed screw sense by chiral Boc-L-amino acid (Boc: t-butoxycarbonyl). Induction in the helix sense through the noncovalent chiral domino effect should be derived primarily from the complex supported by the three-point coordination on the N-terminal sequence. Thus the 3(10)-helical terminus consisting of only alpha-amino acid residues enables chiral recognition of the Boc-amino acid molecule, leading to modulation of the original chain asymmetry. Dynamics in the helix-sense induction also have been discussed on the basis of a low-temperature NMR study. Furthermore, the inversion of induced helix sense has been achieved through solvent effects.

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“…Correlated conformational changes are often linked to chiral amplification phenomenon in synthetic systems (Lockman et al 2005). Chiral amplification in these systems occurs via a 'sergeant and soldiers' mechanism (Green et al 1989) in which a small fraction of chiral subunits/monomers ('sergeants') transmits conformational information to achiral segments ('soldiers') of helical polymer chains, (for some reviews, see Green et al 1999Green et al , 2001Nakano & Okamoto 2001Fujiki 2008;Yashima & Maeda 2008) foldamers (Prince et al 2000;Dolain et al 2005;Maurizot et al 2005;Hou et al 2006;Kolomiets et al 2007;Cai et al 2008;Hu et al 2008;King et al 2008;Kohmoto et al 2008;Naidu et al 2009) or supramolecular assemblies (Engelkamp et al 1999;Ajayaghosh et al 2006;Mateos-Timoneda et al 2006;Nagai et al 2006;George et al 2007;Monti et al 2007;Hembury et al 2008;Lohr & Wuerthner 2008a,b;Praveen et al 2008;Kaiser et al 2009). Although 'sergeants and soldiers' chiral amplification has been achieved in dendritic assemblies (Palmans et al 1997; van Gestel et al 2005;Wilson et al 2006;Shao & Parquette 2008;Percec et al 2009), an intramolecular 'sergeants and soldiers' type chiral amplification remains an unrealized objective for dendrimeric systems.…”

Section: Introductionmentioning

confidence: 99%

Amplification of local chirality within a folded dendrimer. An intramolecular ‘sergeants and soldiers’ experiment

Hofacker

Parquette

2009

Proc. R. Soc. A.

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A series of pyridine-2,6-dicarboxamide dendrons having varying proportions of chiral and achiral termini have been prepared. Circular dichroism and X-ray crystallographic studies indicate that these folded dendrons propagate terminal chirality via a 'sergeants and soldiers' process. The extent of chiral amplification shows a dependence on dendron generation, but also is affected by the relative positioning of the chiral termini at the periphery of the dendron. Analysis of the crystal structures of the G1 dendrons, 4a-6a, reveals chain-chain and chain-dendron conformational communication, which is likely to be responsible for the chiral amplification observed in solution.

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Intramolecular Versus Intermolecular Induction of Helical Handedness in Pyridinedicarboxamide Oligomers

Cited by 64 publications

References 40 publications

Encapsulation of Small Polar Guests in Molecular Apple Peels

Encapsulation of Small Polar Guests in Molecular Apple Peels

Chiral interaction in Gly‐capped N‐terminal motif of 3₁₀‐helix and domino‐type induction in helix sense

Amplification of local chirality within a folded dendrimer. An intramolecular ‘sergeants and soldiers’ experiment

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Intramolecular Versus Intermolecular Induction of Helical Handedness in Pyridinedicarboxamide Oligomers

Cited by 64 publications

References 40 publications

Encapsulation of Small Polar Guests in Molecular Apple Peels

Encapsulation of Small Polar Guests in Molecular Apple Peels

Chiral interaction in Gly‐capped N‐terminal motif of 310‐helix and domino‐type induction in helix sense

Amplification of local chirality within a folded dendrimer. An intramolecular ‘sergeants and soldiers’ experiment

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Chiral interaction in Gly‐capped N‐terminal motif of 3₁₀‐helix and domino‐type induction in helix sense