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1.
    
A series of nucleobased polymers and copolymers were synthesized through atom transfer radical polymerization (ATRP). Biocomplementary DNA‐ and RNA‐like supramolecular complexes are formed in dilute DMSO solution through nucleobase recognition. 1H NMR titration studies of these complexes in CDCl3 indicated that thymine‐adenine (T‐A) and uracil‐adenine (U‐A) complexes form rapidly on the NMR time scale with high association constants (up to 534 and 671 M–1, respectively) and result in significant Tg increase. WAXD and differential scanning calorimetry analyzes in the bulk state indicate the presence of highly physical cross‐linked structures and provide further details into the nature of the self‐assembly of these systems. Furthermore, this study is of discussion on the difference in the hydrogen bond strength between T‐A and U‐A base pairs within polymer systems, indicating that the strength of hydrogen bonds in RNA U‐A pairs is stronger than that in DNA T‐A base pairs. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6388–6395, 2009  相似文献   

2.
    
Polymerization of 11-acryloylaminoundecanoic acid and its copolymerization with diacrylic monomers were performed under different conditions in micellar (Na-salt in water) and non-micellar states. The effect of conditions of the syntheses on molecular mass of the polymers and hydrodynamic characteristics of their macromolecules was studied. Ionic complexes of core-cross-linked polymerized micelles with different dendrons bearing polymerizable peripheral groups were obtained and their trial polymerizations were performed.  相似文献   

3.
    
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4.
    
A series of bicholesteryl‐based gelators with different central linker atoms C, N, and O (abbreviated to GC , GN , and GO , respectively) have been designed and synthesized. The self‐assembly processes of these gelators were investigated by using gelation tests, field‐emission scanning electron microscopy, field‐emission transmission electron microscopy, UV/Vis absorption, IR spectroscopy, X‐ray diffraction, rheology, and contact‐angle experiments. The gelation ability, self‐assembly morphology, rheological, and surface‐wettability properties of these gelators strongly depend on the central linker atom of the gelator molecule. Specifically, GC and GN can form gels in three different solvents, whereas GO can only form a gel in N,N‐dimethylformamide (DMF). Morphologies from nanofibers and nanosheets to nanospheres and nanotubes can be obtained with different central atoms. Gels of GC , GN , and GO formed in the same solvent (DMF) have different tolerances to external forces. All xerogels gave a hydrophobic surface with contact angles that ranged from 121 to 152°. Quantum‐chemical calculations indicate that the GC , GN , and GO molecules have very different steric structures. The results demonstrate that the central linker atom can efficiently modulate the molecular steric structure and thus regulate the supramolecular self‐assembly process and properties of gelators.  相似文献   

5.
    
A number of natural products with potent antimitotic activity are peptides and depsipeptides that bind to tubulin, provoke depolymerization of microtubules, and induce formation of single layer rings of tubulin dimers. These peptides are all hydrophobic and small relative to tubulin (3-5 amino acid residues), yet induce rings polymers with properties that can differ significantly in size and self-association. In addition, these compounds exhibit potent cytotoxicity that varies by several hundred fold from one compound to another. Cryptophycin induces unusually homogeneous rings, composed of eight tubulin dimers, that are stable to dilution at least to nanomolar tubulin concentrations.  相似文献   

6.
    
Supramolecular nanotube hosts with precisely controlled inner or outer diameters have been synthesized by self-assembly of unsymmetrical bolaamphiphilic monomers or glucopyranosylamide lipids, respectively. Time-resolved fluorescent measurement using 8-anilinonaphthalene-1-sulfonate (ANS) as a probe revealed that the water confined in a cardanyl-β-D -glucopyranoside lipid nanotube has relatively lower solvent polarity corresponding to that of propanol than bulk water. Extensively developed hydrogen bond networks also characterize the confined water in comparison to the case in bulk water. Encapsulation ability of the glucopyranosylamide lipid nanotube has been examined by filling the lyophilized LNTs with gold or silver nanoparticles, ferritin, or magnetic crystals. Filling the unsymmetrical bolaamphiphile nanotube possessing positively charged inner surfaces with negatively charged polymer beads or ferritin proved to be successful without depending on capillary action. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5137–5152, 2006  相似文献   

7.
    
A hexabenzocoronene derivative consisting of lipophilic dodecyl side chains and thioacetyl-appended hydrophilic oxyethylene chains was newly synthesized. The self-assembly of this hexabenzocoronene amphiphile in tetrahydrofuran gave a nanotubular object, for which the thioacetyl functionalities were located on the inner and outer surfaces. The removal of the acetyl group under alkaline conditions, followed by autoxidation, allowed the conversion of the noncovalent architecture into a covalently stabilized form via disulfide linkages. The resulting surface-polymerized nanotubes were completely insoluble in common organic solvents. Scanning and transmission electron microscopy showed that the tubular morphology mostly remained after the oxidative polymerization. Disulfide oligomers involved in the polymerized nanotubes were transformed into a thiol monomer upon reduction with dithiothreitol. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5120-5127, 2006  相似文献   

8.
    
The formation of helical structures through the supramolecular polymerization of a variety of self-assembling units is reviewed. These scaffolds are usually obtained by efficient transfer or amplification of chirality phenomena, in which the starting self-assembling molecules possess different elements of asymmetry, such as point or axial chirality. Relevant examples of helical supramolecular structures investigated under thermodynamic control are reviewed, and the helical outcome of remarkable examples of chiral entities obtained through kinetic control are also highlighted. Finally, selected examples of flexible macroscopic chirality and catalysis are described to illustrate the applicability of helical aggregates.  相似文献   

9.
    
Aqueous hybrid soft nanomaterials consisting of plural supramolecular architectures with a high degree of segregation (orthogonal coexistence) and precise hierarchy at the nano- and microscales, which are reminiscent of complex biomolecular systems, have attracted increasing attention. Remarkable progress has been witnessed in the construction of DNA nanostructures obtained by rational sequence design and supramolecular nanostructures of peptide derivatives through self-assembly under aqueous conditions. However, orthogonal self-assembly of DNA nanostructures and supramolecular nanostructures of peptide derivatives in a single medium has not yet been explored in detail. In this study, DNA microspheres, which can be obtained from three single-stranded DNAs, and three different supramolecular nanostructures (helical nanofibers, straight nanoribbons, and flowerlike microaggregates) of semi-artificial glycopeptides were simultaneously constructed in a single medium by a simple thermal annealing process, which gives rise to hybrid soft nanomaterials. Fluorescence imaging with selective staining of each supramolecular nanostructure uncovered the orthogonal coexistence of these structures with only marginal impact on their morphology. Additionally, the biostimuli-responsive degradation propensity of each supramolecular architecture is retained, and this may allow the construction of active soft nanomaterials exhibiting intelligent biofunctions.  相似文献   

10.
    
Supramolecular polymerization, that is, the self-assembly of polymer-like materials through the utilization of the noncovalent bond, has been a developing area of research over the last decade. In this article, we report the synthesis of nucleobase-terminated (N6-anisoyl-adenine and thymine) low-molecular-weight poly(tetrahydrofuran) macromonomers (<2000 g mol−1). The adenine-derived supramolecular telechelic polymer self-assembled in the solid state to yield materials with film- and fiber-forming capabilities. This material was thermally reversible and exhibited a ceiling temperature, above which a drop in viscosity was observed and fibers could no longer be obtained. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3589–3596, 2003  相似文献   

11.
    
We have prepared the amidinium-carboxylate salt bridge-based supramolecular polymer gels from random copolymer of n-butyl acrylate and acrylic acid and a linear polyamidine having N,N′-di-substituted acetamidine group in the main chain. The supramolecular polymer gel with equimolar amounts of carboxy and amidine groups shows a high G′ value of 1.6 MPa at 25°C. In contrast, the gel prepared from the carboxy polymer and linear polyethyleneimine instead of the polyamidine shows liquid-like fluidity with a G′ value of 0.01 MPa at 25°C. The robustness of the amidine-based supramolecular polymer gels is attributed to the high stability of the amidinium-carboxylate salt bridge. Replacing the random copolymer with carboxy-terminated telechelic poly(n-butyl acrylate) results in a significant decrease in G′ as well as |η*|, which may arise from the difference in the network structure due to the arrangement of carboxy groups.  相似文献   

12.
    
Mutations and changes in a protein's environment are well known for their potential to induce misfolding and aggregation, including amyloid formation. Alternatively, such perturbations can trigger new interactions that lead to the polymerization of folded proteins. In contrast to aggregation, this process does not require misfolding and, to highlight this difference, we refer to it as agglomeration. This term encompasses the amorphous assembly of folded proteins as well as the polymerization in one, two, or three dimensions. We stress the remarkable potential of symmetric homo‐oligomers to agglomerate even by single surface point mutations, and we review the double‐edged nature of this potential: how aberrant assemblies resulting from agglomeration can lead to disease, but also how agglomeration can serve in cellular adaptation and be exploited for the rational design of novel biomaterials.  相似文献   

13.
李洁  黄鹏程 《化学进展》2012,(9):1683-1695
芳炔大环是由芳(杂)环和炔键构成的具有规整多边形环状分子结构的化合物,自问世以来即受到化学家和材料学家的广泛关注。芳炔大环具有不会坍塌的刚性骨架,环上特定位置可带有柔性侧链或取代官能团,环平面上大的π电子共轭体系和环上灵活的结合点赋予芳炔大环独特而有趣的超分子性质。本文对芳炔大环的超分子性质作了综述,从大环在溶液中的缔合、热致液晶性质、一维超分子自组装及在基底表面或固-液界面二维自组装4个方面展开评述,介绍了研究方法,着重讨论了分子结构与物质性质的关系,并对芳炔大环的应用前景做了展望,为通过合理设计分子结构来制备满足尺寸、形状及功能要求的新型材料提供借鉴。  相似文献   

14.
    
We report herein studies on the liquid crystalline behavior of a series of supramolecular materials that contain different ratios of two complementary symmetrically-substituted alkoxy-bis(phenylethynyl)benzene AA- and BB-type monomers. One monomer has thymine units placed at either end of the rigid mesogenic core, while the other has N6-(4-methoxybenzoyl)-adenine units placed on the ends. Differential scanning calorimetric and polarized optical microscopy studies have been carried out on these systems. These studies show that the material's behavior is strongly dependent on its thermal history. As a result, the materials can exhibit, on heating, either a liquid crystalline phase, a crystalline phase, or the coexistence of crystalline and liquid crystalline regions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5049–5059, 2006  相似文献   

15.
    
Hierarchical structures are important for transferring and amplifying molecular functions to macroscopic properties of materials. In this regard, rodlike molecules have emerged as one of the most promising molecular building blocks to construct functional materials. Although the self-assembly of conventional molecules containing rodlike components generally results in nematic or layered smectic phases, due to the preferred parallel arrangements of rodlike components, extensive efforts have revealed that rational molecular design provides a versatile platform to engineer rich self-assembled structures. Herein, first successes achieved in polyphilic liquid crystals and rod–coil block systems are summarized. Special attention is paid to recent progress in the conjugation of rodlike building blocks with other molecular building blocks through the molecular Lego approach. Rod-based giant surfactants, sphere–rod conjugates, and dendritic rodlike molecules are covered. Future perspectives of the self-assembly of molecules containing rodlike components are also provided.  相似文献   

16.
An approach to the supramolecular syntheses of discrete multicomponent aggregates of noncovalently bound molecules, i.e., supermolecules, is described. This approach involved the careful analysis of X-ray crystal structures so as to permit a gradual increase in superstructural complexity. Many elaborate supermolecules were synthesized noncovalently from dialkylammonium-containing cations and crown ethers, following the initial observation that the dibenzylammonium ion threads through dibenzo[24]crown-8 to generate a singly stranded, singly encircled [2]pseudorotaxane, principally as a result of and hydrogen bond formation. The scope of the fundamental recognition motif obtained from this initial observation was then broadened, through the use of thread-like ions with multiple dialkylammonium centers and/or larger crown ethers, so that multiply stranded and/or multiply encircled pseudorotaxanes could be prepared. Cations bearing both dialkylammonium and crown ether recognition sites were also used for the nocovalent synthesis of a discrete daisy chain supermacrocycle and the basic recognition motif was combined with other motifs for the production of a wide range of novel superarchitectures. As a greater understanding of the noncovalent interactions governing the self-assembly of the complex superarchitectures was acquired, new protocols for the noncovalent syntheses of doubly docked pseudorotaxanes and interwoven supramolecular bundles, including a supramolecular analogue of the photosynthetic special pair, were developed. The discovery that anions can play a prominent role in the solid-state self-assembly of some of the supermolecules was a valuable spinoff of the research.  相似文献   

17.
    
One of the major goals in systems chemistry is to create molecular assemblies with emergent properties that are characteristic of life. An interesting approach toward this goal is based on merging different biological building blocks into synthetic systems with properties arising from the combination of their molecular components. The covalent linkage of nucleic acids (or their constituents: nucleotides, nucleosides and nucleobases) with lipids in the same hybrid molecule leads, for example, to the so-called nucleolipids. Herein, we describe nucleolipids with a very short sequence of two nucleobases per lipid, which, in combination with hydrophobic effects promoted by the lipophilic chain, allow control of the self-assembly of lipidic amphiphiles to be achieved. The present work describes a spectroscopic and microscopy study of the structural features and dynamic self-assembly of dinucleolipids that contain adenine or thymine moieties, either pure or in mixtures. This approach leads to different self-assembled nanostructures, which include spherical, rectangular and fibrillar assemblies, as a function of the sequence of nucleobases and chiral effects of the nucleolipids involved. We also show evidence that the resulting architectures can encapsulate hydrophobic molecules, revealing their potential as drug delivery vehicles or as compartments to host interesting chemistries in their interior.  相似文献   

18.
    
A novel heterometallic diPdII–diCuII grid‐chain, {[(bpy)4Pd4Cu2L4](NO3)4}n ( 2 ; bpy=2,2′‐bipyridine), was synthesized through a programmable self‐assembly approach from the molecular corners [(bpy)2Pd2(HL)(L)](NO3) ( 1 ) as linkers with CuII nitrate by using the bifunctional H2L ligand featuring primary (pyrazole) and secondary (benzoic acid) groups. Structural analysis revealed that 1D structure 2 consists of one [Cu2(O2CPh)4]n unit as a bridge and two [(bpy)2Pd2L2]n corners. Additionally, the catalytic effect of the heterometallic synergy on the Suzuki coupling reaction by using 2 was further explored.  相似文献   

19.
A range of neutral metal-organometallic coordination networks (MOMNs) containing both backbone and pendant metal sites have been synthesized and characterized. These materials consist of metal ions or metal ion clusters as nodes that are linked by the bifunctional “organometalloligand” (η4-benzoquinone)Mn(CO)3−, which binds through the quinone oxygen atoms. The resulting MOMNs can be rationally designed to a significant extent based upon a knowledge of the electronic and geometrical requirements of the metal ion nodes, the solvent, organometalloligand substituents, and the presence or absence of organic spacers. An impressive range of architectures have been accessed in this manner, suggesting that the use of π-organometallics in coordination directed self-assembly holds much promise.  相似文献   

20.
    
An increased focus exists on the development of materials that might serve as ligament or tendon tissue engineering scaffolds. Requirements for a suitable candidate polymer include biodegradability, biocompatibility, and elasticity. In an attempt to meet these requirements novel citronellol‐containing polyphosphazenes were synthesized, characterized, and crosslinked to generate elastomers. Citronellol was chosen as a side group due to its anti‐inflammatory properties in addition to the presence of a double bond in its structure to permit polymer crosslinking. Alanine ethyl ester was chosen as a co‐substituent to tune hydrolysis rates without severely affecting the glass transition temperatures of the final polymers. Hydrolysis of the uncrosslinked polymers in the form of films in deionized water at 37 °C showed between ～8 and 16% mass loss and between a ～28 and 88% molecular weight decline over 12 weeks. Polymers were also crosslinked using ultraviolet radiation for increasing amounts of time. Preliminary mechanical testing of the homo‐citronellol polymer indicated increasing modulus and decreasing tensile strength with increased crosslink density. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2258–2265  相似文献   

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