Phthaloyl group : a new amino protecting group of deoxyadenosine in oligonucleotide synthesis

A phthaloyl group has been introduced into the N⁶-amino group of deoxyadenosine $\text{via}$ silylation followed by acylation. The phthaloyl group resulted in remarkable retarding effects on depurination, while it could be removed under milder conditions than the benzoyl group. Thus, a tetradeoxyadenylate has been successfully synthesized in high yield.     

2-diphenylmethylsilylethyl group as a new protecting group of internucleotidic phosphates in oligonucleotide synthesis

Internucleotidic phosphates were protected by 2-diphenylmethylsilylethyl which was selectively removed by treatment with tetrabutylammonium fluoride.     

Trityloxyethylamino group for the protection of phosphoryl group in oligonucleotide synthesis

Trityloxyethylamino group was used for the protection of 5′-phosphoryl group of deoxyribonucleoside. This group is not only protecting group of phosphate also the intermediate for the synthesis of d-ppA and d-pppA.     

Self-assembly vesicles made from a cyclodextrin supramolecular complex

Self-assembly vesicles have been made from a cyclodextrin (CD) supramolecular complex, which is cooperatively formed with natural beta-CD, 1-naphthylammonium chloride (NA), and sodium bis(2-ethyl-1-hexyl)sulfosuccinate (AOT) by weak noncovalent interactions. In the complex structure, a NA molecule is included inside a beta-CD molecule while it is coupled with an AOT molecule on one side. The supramolecular structure and morphology of the vesicles were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. The mechanism of vesicle formation and transition is discussed along with the data obtained from induced circular dichroism (ICD) and UV/visible spectroscopy, polarized optical microscopy (POM), and (1)H NMR spectroscopy. Both the fabrication and the transition of vesicles are controlled by the inclusion equilibria and the cooperative binding of noncovalent interactions, which include the "key-lock" principle, electrostatic interactions, pi-pi stacking, and amphiphilic hydrophobic association.     

Self-assembly of biocidal nanotubes from a single-chain diacetylene amine salt

We describe the facile two-step synthesis of nanotubes that form pure, well-defined, nanostructured materials. We have synthesized a secondary amine HBr salt as the headgroup of a single-chain diacetylenic lipid. This molecule can form a number of different self-assembled nanostructures in aqueous or organic solvents. In water, this lipid forms a monodisperse preparation of nanotubes at high yields. Partially dissolving a preparation of nanotubes dried from aqueous solution results in a remarkably organized structure that resembles a nanocarpet. Details of the nanotube structure were investigated by scanning electron microscopy, transmission electron microscopy, and small-angle X-ray spectroscopy. The aqueous nanotubes have a cross-sectional diameter of 89 nm. The walls of the tubes are an exquisitely uniform 27 nm thick and are shown to consist of five lipid bilayers with a repeat spacing of 57.8 A. The chemical structure of the material shows no chiral centers, but suspensions of the nanotubes in an aqueous medium show an unexpected circular dichroism signal. The versatility of this new material as a platform for nanostructure design and synthesis is enhanced by its biocidal activity. This antimicrobial activity along with the regularity the nanostructures will enhance the development of a range of applications from biosensors to artificial retinas.     

Homo- and heteroleptic complexes of four-membered group 13 metal(I) N-heterocyclic carbene analogues with group 10 metal(0) fragments

A series of complexes between recently developed four-membered group 13 metal(I) heterocycles and group 10 metal(0) fragments have been prepared and structurally characterized. One prepared complex, [Pt{Ga[N(Ar)]2CNCy2}3] (Ar = C6H3Pri2-2,6; Cy = cyclohexyl), possesses the shortest Pt-Ga bonds yet reported, the covalent components of which are suggested by theoretical studies to have significant pi character.     

Self-assembly of a hydrophobic groove

Heptakis(2,6-di-O-methyl)-β-cyclodextrin interacts with 5,15-diphenylporphine to produce a 2:1 complex in dimethyl sulfoxide. This complex possesses a hydrophobic groove that circumscribes the metal binding site of the porphyrin moiety.     

Use of 2-methylsulfonylethyl as a phosphorus protecting group in oligonucleotide synthesis via a phosphite triester approach

2-Methylsulfonylethoxy dichlorophosphine has been converted into the mono-N-morpholino derivative and applied for the preparation of 5′-O,N-protected d-nucleoside-3$\text{-}\text{?}$phosphoramidites. The latter intermediates could be used in the presence of 1-hydroxybenzotriazole for the formation of 3′-5′-phosphotriester linkages. The MSE protecting group can be removed selectively and fast under mild basic conditions.     

Self-assembly of doublets from flattened polymer colloids

Bottom-up fabrication methods are used to assemble strong yet flexible colloidal doublets. Part of a spherical particle is flattened, increasing the effective interaction area with another particle having a flat region. In the presence of a moderate ionic strength, the flat region on one particle will preferentially "bond" to a flat region on another particle in a deep (≥10 kT) secondary energy minimum. No external field is applied during the assembly process. Under the right conditions, the flat-flat bonding strength is ≥10× that of a sphere-sphere interaction. Not only can flat-flat bonds be quite strong, but they are expected to remain freely rotatable and flexible, with negligible energy barriers for rotation because particles reside in a deep secondary energy minimum with a ~20-30 nm layer of fluid between the ~1 μm radius particles. We present a controlled technique to flatten the particles at room temperature, the modeling of the interparticle forces for flattened spheres, and the experimental data for the self-assembly of flat-flat doublets.     

Self-assembly of photonic crystals from polymer colloids

This article reviews recent developments in self-assembly of polymer colloids into colloidal crystals, a good candidate material for photonic crystals. Self-assembly strategy has developed as a facile and efficient method to fabricate colloidal crystals. Much research work has been focused on controlling the morphology and improving the quality, as well as finding applications of the colloidal crystals.     

Fluorescent detection of silver(I) and cysteine using SYBR Green I and a silver(I)-specific oligonucleotide

We report on a novel method for the determination of silver ion (Ag⁺) and cysteine (Cys) by using the probe SYBR Green I (SGI) and an Ag+-specific cytosine-rich oligonucleotide (C-DNA). The fluorescence of SGI is very weak in the absence or presence of randomly coiled C-DNA. If, however, C-DNA interacts with Ag⁺ through the formation of cytosine-Ag⁺-cytosine (C-Ag⁺-C) base pairs, the randomly coiled C-DNA undergoes a structural changes to form a hairpin-like structure, thereby increasing the fluorescence of SGI. This fluorescence turn-on process allows the detection of Ag⁺ in the 10–600?nM concentration range, with a detection limit of 4.3?nM. Upon the reaction of Ag⁺ with Cys, Cys specifically removes Ag⁺ from the C-Ag⁺-C base pairs and destroys the hairpin-like structure. This, in turn, results in a decrease in fluorescence intensity. This fluorescence turn-off process enables the determination of Cys in the 8–550?nM concentration range, with a detection limit of 4.5?nM. The method reported here for the determination of either Ag⁺ or Cys is simple, sensitive, and affordable, and may be applied to other detection systems if appropriately selected DNA sequences are available.

Allyl group as a protecting group for internucleotide phosphate and thiophosphate linkages in oligonucleotide synthesis: facile oxidation and deprotection conditions

[reaction: see text] The allyl group, which serves as a protecting group for an internucleotide bond for both phosphates and phosphorothioates, can be easily removed by good nucleophiles under weakly basic or neutral conditions. For a practical synthesis on solid support, camphorsulfonyloxaziridine was used as the oxidizing agent for synthesizing DNA, while the Beaucage reagent was used for preparing phosphorothioate oligomers. Both types of oligonucleotides were easily deprotected by concentrated ammonium hydroxide containing 2% mercaptoethanol.     

Self-assembly of a molecular figure-of-eight strip

A hexanuclear copper(ii) complex with a figure-of-eight strip topology is formed by metal-directed self-assembly of tritopic ligand L, bis-bidentate glycine hydroxamic acid and Cu(ii) ions in a 2:2:6 ratio.     

无模板组装法制备的杂化微囊及其功能特性

纳米颗粒-大分子杂化微囊的独特组成及结构,决定了其同时具有纳米颗粒本身的物理化学性能与微囊的包封、保护和传输功能,在生物医学领域有着极其重要的应用。主要介绍杂化微囊最新的无模板自组装制备方法及其功能特性的研究进展。近几年发展起来的空心微囊无模板自组装制备方法,区别于传统的层层自组装制备方法,基于分子间的静电吸引作用,无...     

Nanostructured Columns from Self-assembly of Complementary Molecular Components

IntroductionIn the past decades, chemists have exp1Ored the relatively weak noncovalent interactionsthat could exist between molecules, and also developed the means to design and fabricate.nanostructures serving as candidate for new matefials[1--4]. When these interactions act in acooperative and convergent way, organized assemblies can be constructed by molecular recog-nition directed self-assembly. Many successful nanostructures have been fabricated via suchmethods[5--9]. However, for the a…