Auslander–Gorenstein resolution

We introduce the notion of Auslander–Gorenstein resolution and show that a Noetherian ring is an Auslander–Gorenstein ring if it admits an Auslander–Gorenstein resolution over another Auslander–Gorenstein ring.     

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.     

Anthranoxides as Highly Reactive Arynophiles for the Synthesis of Triptycenes

We report herein an efficient method to synthesize triptycenes by the reaction of benzynes and anthranoxides, which are electron-rich and readily prepared from the corresponding anthrones. Using this method, 1,9-syn-substituted triptycenes were regioselectively obtained employing 3-methoxybenzynes. This method was also applied to synthesize pentiptycenes. A DFT study revealed that the cycloaddition of lithium anthranoxide and benzyne proceeds stepwise.     

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.     

Derivatization of tributyltin with sodium tetrakis(4-fluorophenyl)-borate for sensitivity improvement of tandem mass spectrometry.

Derivatization of tributyltin for tandem mass spectrometry is described. Tributyltin (TBT) and triphenyltin (TPT) were derivatized with sodium tetrakis(4-fluorophenyl)borate. After optimization of their MS/MS conditions, derivatization conditions were examined. Under the optimum conditions using in-situ derivatization, the calibration curves for the TBT and TPT were linear in the ranges of 0.4 - 200 and 1.2 - 200 pg of Sn, respectively. The detection limits for TBT and TPT were 0.07 and 0.43 pg of Sn, respectively. In the case of TBT, the detection limit with 4-fluorophenylation was improved about five times compared with that with pentylation (0.35 pg). This improvement is ascribed to the bond-dissociation energy of Sn-aryl being stronger than that of Sn-alkyl. Namely, the selective fragmentation of 4-fluorophenyl TBT resulted in high sensitivity. The relative recoveries of TBT and TPT from seawater were 99 and 109%, respectively. The method was successfully applied to the seawater samples.     

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).     

Contribution of recoil implantation to removal of monolayer impurity atoms on metal surfaces

The decay of one monolayer gold atoms at the nickel surface by bombardment with 5 keV Ar⁺ ions at room temperature has been studied by means of the RBS technique. It is found that the gold concentration decreases bi-exponentially with increasing ion fluence. It is shown that the fast decay component gives the removal cross-section which is the summation of the desorption and the recoil-implantation cross-sections. The recoil-implantation cross-section is evaluated from the difference between the removal cross-section and the desorption cross-section obtained at a previous high-temperature experiment.     

Assignment of the 13C-NMR spectrum of phenanthro[4,3-A]dibenzothiophene through the utilization of two-dimensional relayed coherence transfer and double quantum coherence spectroscopy

Total assignment of the ¹³C-nmr spectrum of the helical molecule phenanthro[4,3-a]dibenzothiophene at 125.762 MHz is reported. Assignments were made by the combined application of ¹³C-¹³C autocorrelated double quantum coherence and heteronuclear relayed coherence transfer (RELAY) experiments.     

Successive methyl migrations occurring in the acid treatment of 1-epoxyethyl-1,2,2-trimethyl-cyclopentane derivative

Acid treatment of (IR, 3S,1′S)-1-(1′,2′-Epoxyethyl)-1,2,2-trimethyl-3-acetoxymethyl-cyclopentane $\text{6}$) has been shown to yield three products ($\text{8}$, $\text{9}$, $\text{10}$), among which $\text{8}$ and $\text{9}$ are 1-oxa-bicyclo[3.3.0]octane derivatives formed $\text{via}$ successive methyl migrations followed by an oxorane ring closure.