Fluorescence Response and Self-Assembly of a Tweezer-Type Synthetic Receptor Triggered by Complexation with Heme and Its Catabolites

There is increasing interest in the development and applications of synthetic receptors that recognize target biomolecules in aqueous media. We have developed a new tweezer-type synthetic receptor that gives a significant fluorescence response upon complexation with heme in aqueous solution at pH 7.4. The synthetic receptor consists of a tweezer-type heme recognition site and sulfo-Cy5 as a hydrophilic fluorophore. The receptor–heme complex exhibits a supramolecular amphiphilic character that facilitates the formation of self-assembled aggregates, and both the tweezer moiety and the sulfo-Cy5 moiety are important for this property. The synthetic receptor also exhibits significant fluorescence responses to biliverdin and bilirubin, but shows very weak fluorescence responses to flavin mononucleotide, folic acid, and nicotinamide adenine dinucleotide, which contain smaller π-scaffolds.     

Molecular Transformation to Pyrroles,Pentafulvenes, and Pyrrolopyridines by [2+2] Cycloaddition of Propargylamines with Tetracyanoethylene

In this paper, we describe an efficient and atom-economical synthesis of highly functionalized pyrroles, pentafulvenes, and pyrrolopyridines by [2+2] cycloaddition–retroelectrocyclization of N-substituted propargylamines with tetracyanoethylene, followed by the treatment of the resulting tetracyanobutadiene derivatives with silica gel. In this reaction, silica gel plays an important role to promote the intramolecular cyclization to afford the heterocyclic products from the tetracyanobutadiene intermediates. The products were obtained selectively depending on the substituent on the nitrogen atom of the starting propargylamines.     

Perturbation and renormalization in thermo field dynamics

A systematic renormalization procedure used in the perturbative calculation of the real-time causal Green's functions at finite temperature is presented. The formalism of thermo field dynamics is employed throughout, permitting the use of Feynman diagram techniques. The renormalizability by means of the temperature-independent counterterms is proved.     

Anomalies in the surface impedance penetration depth in ferromagnetic superconductors

We have investigated the surface impedance penetration depth, Λ, of ErRh₄B₄ and Er_0.5Ho_0.5Rh₄B₄ both experimentally and theoretically. For ErRh₄B₄, owing to the critical spin fluctuations just above T_s ( > T_c2), the critical temperature at which surface ferromagnetism appears, Λ^?1 decreases smoothly as T decreases toward T_s. For Er_0.5Ho_0.5Rh₄B₄, the decrease in Λ^?1 owing to spin fluctuations for T ? T_c2 is very small, and Λ^?1 decreases abruptly at T_c2. Theoretical values of Λ^?1 are in good agreement with the data.     

Anion exchange equilibrium of uranium and several other elements in mineral acid solutions containing tetrafluoroboric acid

Volume distribution coefficients /Dv/ were determined for the adsorption of U and several other elements on anion-exchange resin from mixed solutions of tetrafluoroboric acid and nitric acid or hydrochloric acid, and the effect of tetrafluoroboric acid on the adsorption of each element was studied. The addition of tetrafluoroboric acid, in general, slightly decreased the Dv values while Zr was weakly adsorbed in the HBF₄–HCl and HBF₄–HNO₃ solutions and Nb in the HBF₄–HNO₃ solutions.     

A Reversible Fluorescent Probe for Real‐Time Live‐Cell Imaging and Quantification of Endogenous Hydropolysulfides

The chemical biology of reactive sulfur species, including hydropolysulfides, has been a subject undergoing intense study in recent years, but further understanding of their “intact” function in living cells has been limited owing to a lack of appropriate analytical tools. In order to overcome this limitation, we developed a new type of fluorescent probe that reversibly and selectively reacts to hydropolysulfides. The probe enables live‐cell visualization and quantification of endogenous hydropolysulfides without interference from intrinsic thiol species such as glutathione. Additionally, real‐time reversible monitoring of oxidative‐stress‐induced fluctuation of intrinsic hydropolysulfides has been achieved with a temporal resolution on the order of seconds, a result which has not yet been realized using conventional methods. These results reveal the probe's versatility as a new fluorescence imaging tool to understand the function of intracellular hydropolysulfides.     

A novel deaminative cyclization of aminoglycoside. Synthesis of a kanamycin B variant having 2-oxa-5-azabicyclo[2,2,2]oct-1,5-diene ring

The 3′,5′-diene derivative of kanamycin B ($\text{2}$) was obtained from a 4′-ene derivative of kanamycin B ($\text{1}$) by treatment with trimethyl orthoacetate. Formation of the title compound ($\text{4}$) from $\text{2}$ deaminative cyclization with sodium methoxide followed by treatment with trifluoroacetic acid was described.     

Rotaxane Type Complexation Behavior of Cyclodextrins with a Series of Donor–Acceptor Covarently Linked Compounds

The complexation behavior of a series of electron donor–accepter (D–A) covalently linked compounds with cyclodextrins (CyDs) has been reviewed. The structure of these complexes showed rotaxane type conformations, which were investigated by means of ¹ H NMR spectrometry. The complex formations induced a fixation of a conformation of guest D–A molecules, and D–A distances were enlarged. Thus, accurate photo-induced charge transfer behaviors can be discussed.     

Preparation and applications of novel fluoroalkyl end-capped acrylamide oligomers/polythiophene nanocomposites

Thiophene monomer reacted with ferric chloride in the presence of a variety of fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomers [R_F-(DOBAA)_x-R_F] to afford nanometer size-controlled R_F-(DOBAA)_x-R_F oligomers-polythiophene composites [R_F-(DOBAA)_x-R_F/PTh]. R_F-(DOBAA)_x-R_F/PTh nanocomposites thus obtained were demonstrated to have a good dispersibility and stability in methanol to give a transparent brown solution. In addition, these fluorinated nanocomposites were applied to the surface modification of common organic polymers such as poly(methyl methacrylate), and were dispersed regularly above the polymer surface.