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.     

On a dendrite generated by a zero-dimensional weak self-similar set

Let S be a zero-dimensional, perfect, compact weak self-similar set generated in dendrite X by a family {f_j} of weak contractions from X to itself. Decomposition space D_f of S due to a continuous mapping f from S onto X is also a dendrite. In the dendrite D_f, there exists a zero-dimensional, perfect, compact weak self-similar set S¹ based on a family each of which is topologically conjugate to f_j. Decomposition space D_f¹ of S¹ due to a continuous mapping f¹ from S¹ onto D_f is again a dendrite. In this manner, through the successive formation of weak self-similar set, we can obtain a sequence X,D_f,D_f¹,… of dendrite any pair in which are mutually homeomorphic.     

A single-electron circuit as a discrete dynamical system

A single-electron circuit can be operated as a discrete dynamical system because it changes its internal state discontinuously because of electron tunneling. To confirm this idea, we designed a sample circuit for discrete dynamical operation and confirmed by computer simulation that the circuit successfully generated a sequence of discrete-time outputs by following a return map. The concept of discrete dynamical systems will be useful in developing new functional systems that consist of quantum devices and nanostructures.     

Flow of optical patterns due to small lateral wave-front shifts in a nonlinear optical feedback system

Flow of a spontaneously formed optical pattern in a nonlinear optical feedback system consisting of a liquid crystal optically addressable spatial light modulator with feedback is induced by a lateral wave-front shift of the feedback light. We demonstrate the dependency of the flow speed on the wave-front shift by tilting an optical flat inserted in the feedback loop. We also demonstrate the application to real-time, high-sensitivity detection of small tilt angles of optical components.     

Fluorescence labeling method for aryl halides with 4-(4,5-diphenyl-1H-imidazol-2-yl)phenylboronic acid based on Suzuki coupling reaction

For the first time, fluorescence labeling methods for aryl halides with a fluorescent arylboronic acid was developed on the basis of a Suzuki coupling reaction. 4-(4,5-diphenyl-lH-imidazol-2-yl)phenylboronic acid (DPA) was used as a fluorescence labeling reagent. In order to explore its analytical performance, the reaction conditions were optimized using simple bromobenzene derivatives. The reactivity was then investigated with chloro- and iodobenzene derivatives, and also bromobenzene derivatives with different position of substituents. The order of reactivity with DPA: iodobenzene > bromobenzene more more than chlorobenzene derivatives, and p- > m- > o-substituted bromobenzenes. The detection limits of bromobenzene, 4-bromotoluene, and 4-bromoanisole ranged from 0.2 to 1.4 pmol/injection at a signal-to-noise ratio, (S/N) of 3. The applicability of the method to biological samples was also evaluated using clofibrate as the analyte. The reaction was found not only to proceed well but also to be selective for clofibrate even in the presence of plasma components. The method allowed the sensitive detection of clofibrate in human plasma with the detection limit of 170 pmol/mL (260 fmol/injection) at a S/N = 3. The proposed method is highly selective and sensitive and thus would be useful for labeling of aryl halides that do not have other functional groups that could be labeled by currently available fluorescent labeling reagents.     

Whole‐Cell Biotransformation of Benzene to Phenol Catalysed by Intracellular Cytochrome P450BM3 Activated by External Additives

An Escherichia coli whole‐cell biocatalyst for the direct hydroxylation of benzene to phenol has been developed. By adding amino acid derivatives as decoy molecules to the culture medium, wild‐type cytochrome P450BM3 (P450BM3) expressed in E.coli can be activated and non‐native substrates hydroxylated, without supplementing with NADPH. The yield of phenol reached 59 % when N‐heptyl‐l ‐prolyl‐l ‐phenylalanine (C7‐Pro‐Phe) was employed as the decoy molecule. It was shown that decoy molecules, especially those lacking fluorination, reached the cytosol of E. coli, thus imparting in vivo catalytic activity for the oxyfunctionalisation of non‐native substrates to intracellular P450BM3.     

Protic NNN and NCN Pincer‐Type Ruthenium Complexes Featuring (Trifluoromethyl)pyrazole Arms: Synthesis and Application to Catalytic Hydrogen Evolution from Formic Acid

NNN and NCN pincer‐type ruthenium(II) complexes featuring two protic pyrazol‐3‐yl arms with a trifluoromethyl (CF₃) group at the 5‐position were synthesized and structurally characterized to evaluate the impact of the substitution on the properties and catalysis. The increased Brønsted acidity by the highly electron‐withdrawing CF₃ pendants was demonstrated by protonation–deprotonation experiments. By contrast, the IR spectra of the carbonyl derivatives as well as the cyclic voltammogram indicated that the electron density of the ruthenium atom is negligibly influenced by the CF₃ group. Catalysis of these complexes in the decomposition of formic acid to dihydrogen and carbon dioxide was also examined. The NNN pincer‐type complex 1 a with the CF₃ group exhibited a higher catalytic activity than the tBu‐substituted analogue 1 b . In addition, the bis(CF₃‐pyrazolato) ammine derivative 4 catalyzed the reaction even in the absence of base additives.     

Primary cultures of chick osteocytes retain functional gap junctions between osteocytes and between osteocytes and osteoblasts.

The inaccessibility of osteocytes due to their embedment in the calcified bone matrix in vivo has precluded direct demonstration that osteocytes use gap junctions as a means of intercellular communication. In this article, we report successfully isolating primary cultures of osteocytes from chick calvaria, and, using anti-connexin 43 immunocytochemistry, demonstrate gap junction distribution to be comparable to that found in vivo. Next, we demonstrate the functionality of the gap junctions by (1) dye coupling studies that showed the spread of microinjected Lucifer Yellow from osteoblast to osteocyte and between adjacent osteocytes and (2) analysis of fluorescence replacement after photobleaching (FRAP), in which photobleaching of cells loaded with a membrane-permeable dye resulted in rapid recovery of fluorescence into the photobleached osteocyte, within 5 min postbleaching. This FRAP effect did not occur when cells were treated with a gap junction blocker (18alpha-glycyrrhetinic acid), but replacement of fluorescence into the photobleached cell resumed when it was removed. These studies demonstrate that gap junctions are responsible for intercellular communication between adjacent osteocytes and between osteoblasts and osteocytes. This role is consistent with the ability of osteocytes to respond to and transmit signals over long distances while embedded in a calcified matrix.     

Stepwise gradient of buffer concentration for capillary electrochromatography of peptides on sulfonated naphthalimido-modified silyl silica gel

The advantage of using a stepwise gradient of buffer concentration in CEC was demonstrated with the mixed-mode stationary phase, 3-(4-sulfo-1,8-naphthalimido)propyl-modified silyl silica gel (SNAIP). Before the application of a stepwise gradient, the effect of buffer concentration on the separations of six peptides and tryptic digests was investigated. Bubble formation caused by Joule heating at currents up to 95 microA was successfully suppressed by using SNAIP column even without pressurization, which contributed to a stepwise gradient of buffer concentration. Utilizing the stepwise gradient improved and shortened the separation of six peptides as compared to the separation under an isocratic elution.     

Substrate effect on the formation of hydrogels with heterogeneous network structure

It was found that when an aqueous solution of vinyl monomers is polymerized on a hydrophobic substrate, obvious heterogeneity occurs in the region of the interface. This substrate effect was observed on polytetrafluroethylene (Teflon), polypropylene (PP), polyethylene (PE), polystyrene (PS), and polyvinylchloride (PVC), but not on hydrophilic substrates. Compared with synthesis on hydrophilic surfaces, the surfaces of hydrogels synthesized on a hydrophobic substrate exhibit a larger degree of swelling, a lower surface coefficient of friction and elastic modulus, weaker interfacial adhesion, and reduced interaction with biological cells. This substrate effect has been observed for many types of aqueous monomer solutions. It was found that the above properties are related to the loosely cross-linked architecture, containing some graft-like polymer chains, that is formed on the gel surface when the gel is prepared on a hydrophobic substrate. To understand the mechanism of the substrate effect, two novel optical methods, electric speckle pattern interferometry (ESPI) and real-time laser sheet refraction (RT-LSR), were developed. It was found that oxygen trapped in the composite interface between the monomer solution and rough hydrophobic substrates played an important role in the substrate effect.