Photochemically relevant DNA-based molecular systems enabling chemical and signal transductions and their analytical applications

In biology, DNA is the central molecule that stores the genetic information. DNA also has attractive physicochemical features for use as materials in molecular assemblies. DNA is chemically stable and can be prepared in nearly any length and sequence by chemical and enzymatic syntheses. Auxiliary functional groups can be built into the backbone as amidite reagents using automated DNA synthesizers. In addition, we can choose an appropriate method from abundant chemistries for post-modifications. The structures of DNA complexes can be rationally designed by bottom-up self-assembly. Therefore, functional groups can be positioned on the DNA scaffold in distinct distance and spatial arrangements.In the last decade, a number of DNA-based allosteric molecular systems have been reported. Some of the systems function as signal transducers, amplifiers, and chemical catalysts. These systems are rather exciting as fundamental achievements of the studies for nanomachines or nanodevices. They should also be useful as robust molecular sensors for sensitive bioassays. In this review, we will cover the photochemically relevant DNA-based molecular systems. They are classified into three groups: (i) DNA-templated molecular/ion assemblies; (ii) DNA-directed complexation; and (iii) chemical transformations accelerated on DNA.     

Self-Assembled Nanofibrillar Aggregates with Amphiphilic and Lipophilic Molecules

Summary: This article gives a review on self-assembled nanofibrillar aggregates such as helical, twisted ribbon-like and tubular forms, those are produced in aqueous bilayer membrane and organogel systems. Two common features necessary for the chemical structure that yields special morphology are a chiral carbon atom and moieties feasible for intermolecular interactions although there are some exceptions. In aqueous systems, a hydrophobic effect is also an essential driving force for molecular aggregates in aqueous solution systems but almost disappear in organic media. More positive intermolecular interactions play an important role in molecular aggregation in organic media. Hydrogen bonding interaction is especially effective and many organogelators are classified into this category. Some lipophilic peptides have been investigated not only as organogelators but also with respect to their self-assembling behaviors. This latter property gives them distinct advantages compared with conventional gel systems because the gels include highly-ordered structures supramolecular functions like aqueous lipid membranes through molecular orientation. This article also introduces applicability of the organogel system.     

Emission-Color Control in Polymer Films by Memorized Fluorescence Solvatochromism in a New Class of Totally Organic Fluorescent Nanogel Particles

In this work, a new class of totally organic fluorescent nanogel particles and their exceptionally specific behaviors based on their unique structures are introduced, which draws a sharp line from conventional fluorophore-doped and fluorophore-branched-type particles. The nanogel particles, the diameter of which could be controlled by adjusting reaction conditions, such as the solvent system, were spontaneously fabricated with a spherical shape by direct polymerization of non-heterocyclic aromatic compounds, such as 2,6-dihydroxyanthracene, 2,6-dihydroxynaphthalene, and 9,9-bis(4-hydroxyphenyl)fluorene with triazinane as the cross-linker. A fluorophoric moiety formed from a polymer main chain was realized in the particle, and consequently, the resultant content of the fluorophoric moiety was around 70–80 wt % per particle. The uniqueness and versatility of the particles can be emphasized by their good compatibility with various solvents due to their amphiphilic and ampholytic swelling properties, but also by their remarkable fluorescent solvatochromism in the dispersion state. Furthermore, these behaviors were preserved even in their polymer composite system. This study also demonstrates that various fluorescent polymer films can be fabricated with emission color control due to memorization of the solvatochromism phenomenon of the dispersed fluorescent nanoparticles.     

Intramolecular double michael reaction III Stereoselective chiral synthesis of atisiran-15-one

Atisiran-15-one (5) was stereoselectively synthesized starting from the ketone (10) through the intramolecular double Michael reaction.     

A novel synthesis of benzo- and indolo[a]quinolizidines by intramolecular diels-alder reaction of l-azadienes

Intramolecular Diels-Alder reaction of l-azadienes was conducted by heating the α,β-unsaturated amides (2a ～ d and 6) in the presence of trimethyl- chlorosilane, triethylamine and zinc chloride to give benzo- and indolo[a]- quinolizidines (5a ～ e and 7).     

Chromatographic resolution of dipeptide enantiomers and diastereomers on chiral stationary phases from poly-( -leucine) or poly( -phenylalanine)

Two types of chiral stationary phase, polymer-bonded and non-bonded, containing poly( -leucine) and poly( -phenylalanine) were prepared. These stationary phases gave higher enantioselectivity for the optical resolution of various derivatives of leucylphenylalanine methyl ester by liquid chromatography than did poly( -alanine) and poly( -glutamate).     

Michael addition of N-isobutylidene-t-butylamine to dimethyl methoxymethylenemalonate and a new synthesis of some fused pyrazole derivatives from the adduct

N-Isobutylidenemethylamine reacted with dimethyl methoxymethylenemalonate to afford the N-alkylation product 3a exclusively. Exchanging the N-substituent of the Schiff's base from methyl to t-butyl altered the course of the reaction, allowing Michael addition to take place predominantly. The Michael adduct 4c on reaction with hydrazinoalkanols 6a,b, 6c,d and 6e gave tetrahydropyrazolo[5,1-b]oxazoles 9a,b , tetrahydro-pyrazolo[5,1-b][1,3]oxazines 9c,d and hexahydropyrazolo[5,1-b][1,3]oxazepine 9e , respectively.     

One-pot assembly of tricyclo[6.2.1.0(1,6)]undecan-4-one and related polycyclic compounds by tandem electroreductive cyclization

[reaction: see text] Electroreductive tandem cyclization of 4-allyl-4-(2-bromoprop-2-en-1-yl)cyclohex-2-en-1-one to tricyclo[6.2.1.0(1,6)]undecan-4-one has been demonstrated. This protocol represents an attractive alternative to conventional tandem radical cyclization.     

On Galois representations arising from towers of coverings of P1\{0, 1, ∞}

Summary We propose a new way to describe, universally, thel-adic Galois representations associated to each almost pro-l tower of etale coverings ofP ¹\{0, 1, }. This generalizes our universal power series for Jacobi sums (cf. [I]) which arises from the tower of Fermat curves of degreel ⁿ (n), and contains the case of the tower of modular curves of level 2ml ⁿ (m: fixed,n) as another important special case. As a fundamental tool, we shall establish and use an almost pro-l version of the theorems of Blanchfield and of Lyndon in Fox free differential calculus.