Self-Complementarity Achieved through Quadruple Hydrogen Bonding

Beijer, Felix H.; Kooijman, Huub; Spek, Anthony L.; Sijbesma, Rint P.; Meijer, E. W.

doi:10.1002/(sici)1521-3773(19980202)37:1/2<75::aid-anie75>3.0.co;2-r

Cited by 305 publications

(178 citation statements)

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“…Lowering the temperature of the aqueous sample resulted in changes in the proton NMR spectrum suggestive for aggregation; a broadening of the signals occurred pointing to hydrophobic arene-arene stacking and, more importantly, signals at positions typical for hydrogen-bonded protons appeared between 9 and 10.5 ppm (Fig. 3) (28). Initially, only broadening of the signals was observed, similar as for 3 in water at low temperatures.…”

Section: Resultsmentioning

confidence: 77%

“…1 Upper). These positions are typical for molecules dimerized via self-complementary hydrogen bonding; the three hydrogen-bonded protons are visible at low field, whereas the nonhydrogen-bonded amine proton can be found at high field (28). Monofunctional 3 also dissolves readily in water, and the spectra between 11 and 5.3 ppm at different temperatures are given in Fig.…”

Section: Resultsmentioning

confidence: 90%

“…1 H-NMR spectroscopy revealed that 4 dimerizes in chloroform via self-complementary 4-fold hydrogen bonding (28) (Fig. 2 Lower), which affords a supramolecular polymer (4).…”

Section: Resultsmentioning

confidence: 99%

“…Self-complementary apolar molecules 1 and 2 dimerize via strong cooperative 4-fold hydrogen bonding (ADAD) in chloroform (28), giving rise to the formation of a dimer by 1 and a random coil polymer by 2, the latter featuring viscous solutions at higher concentrations. Additional to the hydrogen bonding, solvophobic interactions between the aromatic surfaces arise for 1 and 2 in alkanes.…”

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confidence: 99%

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Hierarchical formation of helical supramolecular polymers via stacking of hydrogen-bonded pairs in water

Brunsveld

Vekemans

Hirschberg

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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Bifunctional ureido-s-triazines provided with penta(ethylene oxide) side chains are able to self assemble in water, leading to helical columns via cooperative stacking of the hydrogen-bonded pairs (DADA array). Monofunctional ureido-s-triazines do not form such helical architectures. The presence of a linker, covalently connecting the two ureido-s-triazine units, is essential as it generates a high local concentration of aromatic units, favorable for stacking interactions. This hydrophobic stacking of the aromatic units occurs at concentrations as low as 5⅐10 ؊6 M and can be visualized by using fluorescence spectroscopy. The stacking generates a hydrophobic microenvironment that allows intermolecular hydrogen bonding to occur at higher concentrations because the hydrogen bonds are shielded from competitive hydrogen bonding with water. This hierarchical process results in the formation of a helical self-assembled polymer in water at concentrations above 10 ؊4 M. Chiral side chains attached to the ureido-striazine units bias the helicity of these columns as concluded from CD spectroscopy and ''Sergeants and Soldiers'' experiments.I n DNA, the well known double helical motif originates from self assembly and is directed by lateral hydrogen bonds between bases and stabilized by solvophobic interactions between the covalently linked bases perpendicular to the hydrogen bonds (1). Control over the intrinsic helicity of the structure is governed by the peripheral chirality in the sugar-phosphate backbone. In synthetic systems, noncovalent interactions have been used to obtain well defined self-assembled architectures in organic solvents (2-7). Peripheral chiral centers in assemblies (8-11) and chiral side chains attached to a polymer backbone (12-20) have been shown to bias chirality at the supramolecular level. Highly ordered multimolecular supramolecular structures stable in water, held together by hydrophobic interactions or with additional hydrogen bonding, are also known (21-25). However, it remains difficult to exploit directional noncovalent interactions in a cooperative way for the formation of discrete multimolecular assemblies stable in water. In this solvent, water molecules strongly compete with directional polar interactions such as hydrogen bonds, resulting in low association constants.The formation of helical self-assembled polymers in solution by both stacking and hydrogen bonding has recently been demonstrated by us (26, 27). Self-complementary apolar molecules 1 and 2 dimerize via strong cooperative 4-fold hydrogen bonding (ADAD) in chloroform (28), giving rise to the formation of a dimer by 1 and a random coil polymer by 2, the latter featuring viscous solutions at higher concentrations. Additional to the hydrogen bonding, solvophobic interactions between the aromatic surfaces arise for 1 and 2 in alkanes. Association via hydrogen bonding of the ureido-s-triazine functional groups leads to the formation of a large and planar aromatic core surrounded by six flexible chains, a structure that is conduciv...

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Section: Resultsmentioning

confidence: 77%

Section: Resultsmentioning

confidence: 90%

“…1 H-NMR spectroscopy revealed that 4 dimerizes in chloroform via self-complementary 4-fold hydrogen bonding (28) (Fig. 2 Lower), which affords a supramolecular polymer (4).…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Hierarchical formation of helical supramolecular polymers via stacking of hydrogen-bonded pairs in water

Brunsveld

Vekemans

Hirschberg

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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196

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“…S6), but in each case E bond ≈ 7 K B T or 16 kJ/mol. 22 The second requirement can be met through phase separation. 23,24 If the polymer is dissolved along with an excess of secretion liquid in a volatile solvent (in our case silicone oil and tetrahydrofuran (THF), respectively), rapid evaporation of the solvent can then be expected to trigger crosslinking of the polymer, trapping some of the secretion liquid within the polymer network while leaving the excess to form droplets within the matrix.…”

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confidence: 99%

Dynamic polymer systems with self-regulated secretion for the control of surface properties and material healing

et al. 2015

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Approaches for regulated fluid secretion, which typically rely on fluid encapsulation and release from a shelled compartment, do not usually allow for a fine, continuous modulation of secretion, and can be difficult to adapt for monitoring or functionintegration purposes. 1-5 Here, we report self-regulated, self-reporting secretion systems consisting of liquid-storage compartments in a supramolecular polymer-gel matrix with a thin liquid layer on top, and demonstrate that dynamic liquid exchange between the compartments, matrix and surface layer allows for repeated, responsive self-lubrication of the surface layer and for cooperative healing of the matrix. Depletion of the surface liquid or local material damage induces self-regulated secretion of the stored liquid via a dynamic feedback between polymer crosslinking, droplet shrinkage and liquid transport that can be read out through changes in the system's optical transparency. We envision diverse applications in fluid delivery, wetting and adhesion control, and material self-repair.Nearly every form of living tissue autonomously packages, transports, and secretes fluids, mediating defense, adhesion, wound healing, temperature -often several of these at once -through tightly self-regulated release systems. [6][7][8][9] Fundamental to these systems, fluid storage is itself an active, finely regulated balance. Storage droplets or vesicles continuously adjust their size, shape and contents through ongoing exchange with the surroundings, creating intrinsically responsive control mechanisms that tie secretion to a wide range of chemical and physical stimuli and feedback signals. [10][11][12][13] At the same time, collective changes in the stores are reported to the organism, alerting it that it needs to drink or eat to replenish the limited supply. Many synthetic approaches have been developed to enable triggered release from microcapsules, hydrogels, nanoparticles, vesicles, micelles, mesoporous carriers and other containers. [1][2][3][4][5][14][15][16][17] While these systems can secrete fluid in response to various stimuli, it remains a challenge to design a synthetic approach that displays finely tuned, continuous self-adjustment, integrated functionalities, and continuous liquid supply monitoring.2 Figure 1. Schematic of the self-regulated, liquid secretion system. Secretion liquid is stored as shell-less droplets inside a gel matrix composed of dynamic polymers, with ongoing liquid exchange between droplet and gel phases. If S = γ ga -(γ la + γ gl ) > 0, the matrix surface will be coated with a thin liquid overlayer. When this layer is removed, the disjoining pressure will trigger secretion of the stored liquid to restore the original film thickness, while the supramolecular gel matrix reconfigures through reversible bond disassembly and reassembly to release any buildup of mechanical stress due to shrinking droplets. With successive removal/restoring cycles, the liquid droplets will continuously shrink and the gel will become progressively transparent.Inspire...

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Durch C−H⋅⋅⋅S- und C−H⋅⋅⋅Se-Brücken stabilisierte Sapphyrin-Supermoleküle – erste strukturelle Charakterisierung von Heteroatome enthaltendenmeso-Arylsapphyrinen

et al. 1998

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Self-Complementarity Achieved through Quadruple Hydrogen Bonding

Cited by 305 publications

References 3 publications

Hierarchical formation of helical supramolecular polymers via stacking of hydrogen-bonded pairs in water

Hierarchical formation of helical supramolecular polymers via stacking of hydrogen-bonded pairs in water

Dynamic polymer systems with self-regulated secretion for the control of surface properties and material healing

Durch C−H⋅⋅⋅S- und C−H⋅⋅⋅Se-Brücken stabilisierte Sapphyrin-Supermoleküle – erste strukturelle Charakterisierung von Heteroatome enthaltendenmeso-Arylsapphyrinen

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