Tetraalkoxyphenanthrene‐Fused Dehydroannulenes: Synthesis,Self‐Assembly,and Electronic,Optical, and Electrochemical Properties

Novel tetraalkoxyphenanthrene‐fused dehydro[12]‐, [18]‐, and [24]annulenes 1 – 3 were synthesized by using Cu‐mediated or Pd‐catalyzed oxidative macrocyclization reactions as key steps, and their electronic, optical, and electrochemical properties have been investigated in detail. X‐ray crystallographic analysis of a single crystal of 1 a demonstrated that the molecules were arranged longitudinally in a slipped π‐stacked fashion to form a 1D column. ¹H NMR and UV/Vis spectroscopic and cyclic voltammetric analysis in conjugation with nucleus‐independent chemical shift (NICS) calculations for 1 – 3 support that the annulation at the 9,10‐positions of phenanthrene to the dehydroannulene ring enhances the tropicity and decreases the HOMO–LUMO gaps of the molecules relative to the benzannulation and that 1 possesses an antiaromatic character. Self‐association behavior due to π–π stacking in CDCl₃ was observed for 1 and 2 and was quantified by concentration‐dependent ¹H NMR spectroscopic measurements. The self‐assembly of 1 and 2 into well‐defined 1D superstructures with high aspect ratios were obtained, and the morphology and crystallinity of these compounds were investigated by means of SEM and wide‐angle X‐ray diffraction (WAXD) measurements. Furthermore, it was shown that 1 b and 2 b display liquid‐crystalline phases by means of differential scanning calorimetry, polarizing optical microscopy, and variable‐temperature WAXD measurements.     

Design and synthesis of amidine-type peptide bond isosteres: application of nitrile oxide derivatives as active ester equivalents in peptide and peptidomimetics synthesis

Amidine-type peptide bond isosteres were designed based on the substitution of the peptide bond carbonyl (C=O) group with an imino (C=NH) group. The positively-charged property of the isosteric part resembles a reduced amide-type peptidomimetic. The peptidyl amidine units were synthesized by the reduction of a key amidoxime (N-hydroxyamidine) precursor, which was prepared from nitrile oxide components as an aminoacyl or peptidyl equivalent. This nitrile oxide-mediated C-N bond formation was also used for peptide macrocyclization, in which the amidoxime group was converted to peptide bonds under mild acidic conditions. Syntheses of the cyclic RGD peptide and a peptidomimetic using both approaches, and their inhibitory activity against integrin-mediated cell attachment, are presented.     

Cytosine-phosphodiester-guanine oligodeoxynucleotide (CpG ODN)-capped hollow mesoporous silica particles for enzyme-triggered drug delivery

We designed, for the first time, an enzyme-triggered drug delivery system that is based on cytosine-phosphodiester-guanine oligodeoxynucleotide (CpG ODN)-capped hollow mesoporous silica (HMS) particles as carriers. Fluorescein dye was used as a model drug, and the fluorescein loading, amino-grafting and CpG ODN capping were evaluated by UV/Vis analysis, zeta potential and N(2) adsorption-desorption measurements and gel electrophoresis. The fluorescein loading capacity and CpG ODN capping amount were 37.7 and 39.6 μg mg(-1), respectively at the weight ratio of 10 Dye/HMS-NH(2)/CpG ODN. Importantly, fluorescein release can be triggered by the addition of deoxyribonuclease I (DNase I) for CpG ODN degradation, and the release rate can also be controlled by changing the DNase I concentration. Therefore, it might be a promising controlled drug delivery system for application in the field of biomedicine and cancer therapy.     

Metal-free C-H cross-coupling toward oxygenated naphthalene-benzene linked biaryls

The intermolecular C-H cross-coupling between aromatic ethers has been achieved for the first time using perfluorinated hypervalent iodine(III) compounds as extreme single-electron-transfer (SET) oxidants. The demonstrations of this specific coupling could provide a direct route to valuable oxygenated mixed naphthalene-benzene biaryls 3 only, without formation of other biaryl-derived byproducts.     

Post-translational His-Cys cross-linkage formation in tyrosinase induced by copper(II)-peroxo species

Autocatalytic formation of His-Cys cross-linkage in the enzyme active site of tyrosinase from Aspergillus oryzae has been demonstrated to proceed by the treatment of apoenzyme with Cu(II) under aerobic conditions, where a (μ-η(2):η(2)-peroxo)dicopper(II) species has been suggested to be involved as a key reactive intermediate.     

Elemental distribution analysis of type I collagen fibrils in tilapia fish scale with energy-filtered transmission electron microscope

Elemental distribution of calcium, phosphorus, oxygen, and carbon in a single collagen fibril obtained from tilapia fish scales was identified with an electron energy-loss spectroscopy and an energy-filtered transmission electron microscopy, for the first time. The carbon intensity profile of the single collagen fibril showed the specific D-periodic pattern at 67 nm of type I collagen fibrils. The calcium L_2,3-edge and oxygen K-edge peak positions were detected at 347/350 eV and 137 eV, respectively, and these positions were identical to those of hydroxyapatite. Calcium, phosphorus, and oxygen were present in the hole zones as the amorphous phase, while carbon was present in the overlap zone. Our results indicated that the hole zones preferentially attract calcium and phosphate ions and thus serve as possible nucleation sites for mineralization.     

Bulldozer blade control

A simple control system for controlling a bulldozing blade was developed and tested. Both controls of the bulldozing load acting on the bulldozer blade and the blade position control were validated through an operational test. It was observed that the application of this control system could not only reduce the frequent up and down actions of adjusting the bulldozer blade considering the conditions of the load applied and the irregularity of terrain surface, but also could allow the operator to concentrate on the steering during the operation of earth moving.     

Castasterone,a new phytosterol with plant-hormone potency,from chestnut insect gall

A sterol which has strong potency to inclinate rice lamina was isolated from the insect gall of the chestnut tree. The structure was determined to be (22R, 23R, 24S)-2α, 3α, 22, 23-tetrahydroxy-24-methyl-5α-cholestan-6-one ($\text{1}$).