pH-dependent reversible polymers formed from cyclic sugar- and aromatic boronic acid-based bolaamphiphiles

Nakazawa, Ikuo; Sakae, Suda; Masuda, Mitsutoshi; Asai, Michihiko; Shimizu, Toshimi

doi:10.1039/b001013h

Cited by 60 publications

(40 citation statements)

References 15 publications

(22 reference statements)

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“…Reversible reactions are presently receiving increasing attention and provide a means for developing new materials exhibiting unusual features. Recent covalent polymers investigated for their reversible properties have included entities based on various reactions, such as transesterification (12)(13)(14)(15), transetherification (16), Diels-Alder reaction (17,18), [2 ϩ 2] photodimerization (19), radical reaction (20), and boronate ester formation (21).…”

Section: Reversibility Exchange and Diversitymentioning

confidence: 99%

Dynamers: Polyacylhydrazone reversible covalent polymers, component exchange, and constitutional diversity

Skene

Lehn

2004

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

301

195

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Component exchange in reversible polymers allows the generation of dynamic constitutional diversity. The polycondensation of dihydrazides with dialdehydes generates polyacylhydrazones, to which the acylhydrazone functionality formed confers both hydrogen-bonding and reversibility features through the amide and imine groups, respectively. Polyacylhydrazones are thus dynamic polyamides. They are able to reversibly exchange either one or both of their repeating monomer units in the presence of different monomers, thus presenting constitutional dynamic diversity. The polymers subjected to monomer exchange͞interchange may be brought to exhibit physical properties vastly different from those of the original polymer. The principle may be extended to other important classes of polymers, giving access, for instance, to dynamic polyureas or polycarbamates. These reversible polymers are therefore able to incorporate, decorporate, or reshuffle their constituting monomers, namely in response to environmental physical or chemical factors, an adaptability feature central to constitutional dynamic chemistry.constitutional dynamic chemistry ͉ reversible polymers ͉ dynamic materials B lending supramolecular chemistry with materials science defines a field of supramolecular materials that rests on the explicit implementation of intermolecular interactions in the design and synthesis of novel materials presenting novel properties.Because supramolecular chemistry is by nature a dynamic chemistry in view of the lability of the noncovalent interactions connecting the molecular components of a supramolecular entity, supramolecular materials are by nature dynamic materials (1-3).Importing such dynamic features, characteristic of supramolecular chemistry, into molecular chemistry implies looking at molecules as labile entities, in contrast to the usual longing for stability, thus opening novel perspectives to covalent chemistry. It requires searching for reversible reactions that allow the making and breaking of covalent bonds, preferentially under mild conditions. These developments are embodied in the recent emergence of dynamic combinatorial chemistry as a powerful means for generating dynamic, effector-responsive molecular diversity (2, 4).Thus, on both the supramolecular and molecular levels, dynamic materials may be defined as materials whose constituents are linked through reversible connections (noncovalent or covalent) and are able to undergo continuous reorganization through assembly͞disassembly processes, incorporation, extrusion, or reshuffling of components in a given set of conditions, usually under thermodynamic control (1, 2).The resulting constitutional plasticity defines a constitutional dynamic chemistry (3) encompassing both covalent molecular (2, 5) and noncovalent supramolecular entities.Focusing on a specific class of materials, polymers, the pathway leads from supramolecular polymers (6-8) to dynamic covalent polymers (see ref. 5, pp. 902-915). One may designate under the term, Dynamers (7), both the polymers that...

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Section: Reversibility Exchange and Diversitymentioning

confidence: 99%

Dynamers: Polyacylhydrazone reversible covalent polymers, component exchange, and constitutional diversity

Skene

Lehn

2004

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

301

195

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“…[8] The polycondensation of diboronic acids with sugar derivatives as linkers has been investigated by the groups of Shinkai [11] and Shimizu. [12] Again it was found that the polymerization is a reversible process, which depends on the conditions. An alternative way to generate dynamic polymers with boron centers in the backbone is the polymerization by dative B-N bonds.…”

Section: Introductionmentioning

confidence: 98%

Formation of Boronate Ester Polymers with Efficient Intrastrand Charge‐Transfer Transitions by Three‐Component Reactions

et al. 2007

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The three-component reaction of aryl boronic acids with 1,2,4,5-tetrahydroxybenzene and 1,2-bis(4-pyridyl)ethylene or 4,4Ј-bipyridine leads to the formation of dark-purple boronate ester polymers. Crystallographic analyses show that the polymer strands have a zig-zag geometry, and the bis(dioxaborole) units are connected by dipyridyl linkers through dative B-N interactions. Upon dissolution of the polymers in hot chloroform, most of the B-N connections are

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“…58 Of particular note is that the reversible polymer formation and dissociation were achieved depending on pH conditions of the aqueous solutions used.…”

Section: Ph-dependent Reversible Polymer Formation From Bola-form Dermentioning

confidence: 99%

“…[56][57][58] The self-assembling behavior and the obtained morphologies were examined using confocal laser scanning, dark-field, polarized, and phase-contrast light microscopy. When saturated, hot aqueous solutions containing 1(n) or 3(n) were allowed to gradually cool and stand at room temperature, a variety of supramolecular fibers (nanofibers) with nanometer-sized dimension spontaneously and reproducibly appeared, strongly dependent on both the spacer length and the even/odd spacer carbon numbers ( Figure 2).…”

Section: Formation Of Self-assembled Supramolecular Fibersmentioning

confidence: 99%

Bottom-Up Synthesis and Morphological Control of High-Axial-Ratio Nanostructures through Molecular Self-Assembly

Shimizu

2003

Polym J

Self Cite

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ABSTRACT:Based on our recent results, the present paper overviews noncovalent formation of high-axial-ratio nanostructures (HARNs), such as fibers, rods, tubes and ropes, through molecular self-assembly of bola-form amphiphilic (bolaamphiphilic) monomers. A variety of bolaamphiphiles, in which sugars, peptides, or nucleobases as headgroups are connected to both ends of a hydrocarbon spacer, were newly designed and synthesized. Their self-assembling behavior was examined in aqueous solutions in terms of bottom-up fabrication of organic nanostructures. The morphologies proved to strongly depend on the headgroup structure, spacer chain lengths and even-odd carbon numbers of used oligo(methylene) spacers. Typical examples of self-assembled morphologies include nanofibers from 1-glucosamide-or thymidine-appended bolaamphiphiles, vesicle-encapsulated microtubes from glycylglycine-appended bolaamphiphiles, double-helical ropes from thymine-appended bolaamphiphiles. These self-assembled HARNs are constructed hierarchically in a manner similar to biological structures. On the basis of several solid-state analyses, molecular packing and orientation within the HARNs are discussed and compared with the single crystal structures in terms of hydrogen-bond networks. Furthermore, pH-dependent reversible polymer formation was achieved using the combination of glucuronamideand aromatic boronic acid-appended bola-form derivatives. Polymerization of bola-form 1-glucosamide derivatives with a 1,4-butadiyne group was performed in self-assembled nanometer-sized fibers, giving a single polydiacetylene chain of 64-mer that can be seen in TEM.KEY WORDS High-Axial-Ratio Nanostructure (HARN) / Bolaamphiphile / Self-Assembly / Noncovalent Synthesis / Hydrogen Bond / Nanofiber / Microtube / Nano-Rod / Rope / Hydrogel / Crystal Structure / Biomaterials possess highly organized non-covalent structures formed spontaneously in bottom-up fashion, 1 shaping natural body and functioning as energyconverting and information-converting materials. In contrast, conventional polymers are so-called linear macromolecules in which tens of thousands to millions of low-molecular-weight monomer units are connected to each other through covalent bonds. Very recently, a new family of polymers, including topologically complex polymers 2-13, 18-25 and self-assembled nanostructures, [14][15][16][17]26 has attracted much attention. 27,28 In particular, Kunitake and his co-worker built up the fundamental concept behind the polymolecular materials based on bilayer-containing molecular assemblies. 29,30 Stupp et al., 31, 32 Percec et al., 33 and Whitesides et al. 34,35 also succeeded in a molecule-up fabrication using polymer building blocks to realize nanometersized assemblies with well-defined shapes. The advantage of non-covalent self-assembly technique, unlike chemical reaction or polymerization, is in that it can directly produce ordered two-and three-dimensional structures like sheets, rods, fibers, tubes, disks, and spheres. It is more important that nanostruct...

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pH-dependent reversible polymers formed from cyclic sugar- and aromatic boronic acid-based bolaamphiphiles

Abstract: Glucuronamide-based bolaamphiphiles are found to form a reversible, linear polymolecular array, via a boronate ester linkage attached to the 1,2-positions of the pyranose or furanose ring, upon complexation with an aromatic boronic acid-based homologue in aqueous solutions.

Cited by 60 publications

References 15 publications

Dynamers: Polyacylhydrazone reversible covalent polymers, component exchange, and constitutional diversity

Dynamers: Polyacylhydrazone reversible covalent polymers, component exchange, and constitutional diversity

Formation of Boronate Ester Polymers with Efficient Intrastrand Charge‐Transfer Transitions by Three‐Component Reactions

Bottom-Up Synthesis and Morphological Control of High-Axial-Ratio Nanostructures through Molecular Self-Assembly

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