Synthesis and structure of the dithienostannole anion

Novel dithienostannoles were synthesized by the reactions of the corresponding dilithiobithiophenes with dichlorodiphenylstannane. A unique byproduct, 10-membered ring compound was also obtained. Reduction of type A dithienostannole with lithium afforded 2,2′-dilithio-3,3′-bithiophene, while reduction of type B dithienostannole with lithium afforded the corresponding dithienostannole anion. The structure and aromaticity of the dithienostannole anion are also discussed.     

Complementary hydrogen-bonding between thymidine-based low molecular-weight gelator and polynucleotide in organic media

We have found that aggregation mode and gelation property of thymidine-based organogelator are affected by the addition of its complementary polynucleotide in organic media.     

A new strategy toward the total synthesis of stachyflin,a potent anti-influenza A virus agent: concise route to the tetracyclic core structure

[reaction: see text] A new strategy directed toward the total synthesis of stachyflin, a potent and novel anti-influenza A virus agent isolated from a microorganism, has been presented through the enantioselective synthesis of the tetracyclic core structure. The synthetic method features a BF(3) x Et(2)O-induced domino epoxide-opening/rearrangement/cyclization reaction as the key step.     

High‐resolution resist for screen printing: application to direct fabrication of Ag circuit

High‐resolution screen printing was devised. New resist formulation contains a base polymer, which consists of acid‐labile tetrahydropyranyl‐protected carboxylic acid, hydroxyl, and methacrylic functions. As crosslinkers, multifunctional acrylates were employed. Photoacid generators were used for pattern formation. A 10‐µm feature size of resist on a screen plate was obtained on irradiation at 365 nm and followed by development on a stainless steel screen. Post‐exposure curing improved the mechanical characteristics of the resist patterns. A 13‐µm feature size silver circuit was successfully printed on poly(ethylene terephthalate) film without defect. Copyright © 2011 John Wiley & Sons, Ltd.     

Characterization of DNA hybridization on partially aminated diamond by aromatic compounds

Here, we report a novel method of micropatterning oligonucleotides via aromatic groups as linkers on partially amino-terminated diamond and the inherence on subsequent hybridization. The covalent immobilization of probe oligonucleotides and characterization of immobilized probe oligonucleotides with carboxylic compounds were investigated by X-ray photoelectron spectroscopy (XPS). To confirm the effects of linker flexibility in a low amino group on diamond for probe oligonucleotides, three kinds of dicarboxylic compound--adipic acid, terephthalic acid, and trimesic acid--were used for immobilization of probe oligonucleotides, like linkers; and these oligonucleotides were hybridized with target oligonucleotides labeled with Cy 5 on the micropatterned diamond surface. The hybridization intensities determined by epifluorescence microscopy were compared and analyzed.     

'Supramolecular wrapping chemistry' by helix-forming polysaccharides: a powerful strategy for generating diverse polymeric nano-architectures

We have exploited novel supramolecular wrapping techniques by helix-forming polysaccharides, β-1,3-glucans, which have strong tendency to form regular helical structures on versatile nanomaterials in an induced-fit manner. This approach is totally different from that using the conventional interpolymer interactions seen in both natural and synthetic polymeric architectures, and therefore has potential to create novel polymeric architectures with diverse and unexpected functionalities. The wrapping by β-1,3-glucans enforces the entrapped guest polymer to adopt helical or twisted conformations through the convergent interpolymer interactions. On the contrary, the wrapping by chemically modified semi-artificial β-1,3-glucans can bestow the divergent self-assembling abilities on the entrapped guest polymer to create hierarchical polymeric architectures, where the polymer/β-1,3-glucan composite acts as a huge one-dimensional building block. Based on the established wrapping strategy, we have further extended the wrapping techniques toward the creation of three-dimensional polymeric architectures, in which the polymer/β-1,3-glucan composite behaves as a sort of amphiphilic block copolymers. The present wrapping system would open several paths to accelerate the development of the polymeric supramolecular assembly systems, giving the strong stimuli to the frontier of polysaccharide-based functional chemistry.     

Post-polymerization of preorganized assemblies for creating shape-controlled functional materials

Combination of supramolecular chemistry with molecular recognition has been successfully applied to creating large superstructures with a wide variety of morphologies. Control of shapes and patterns of ordered molecular assemblies in nano and micro scales has attracted considerable interest as promising bottom-up technology. It is known, however, that these molecular assembling superstructures are fragile, reflecting the characteristic of the non-covalent interaction, a driving force operating in these molecular systems. In fact, they easily collapse or change by small perturbation in the environmental conditions. Thus, over the last decade, researchers have been seeking possible methods for the immobilization these superstructures. This critical review focuses on recent advances in in situ post-modification under the influence of the molecular assemblies as templates and polymerization of ordered molecular assemblies such as organogel fibers and crystals to preserve their original superstructures and intensify their mechanical strength.