Three new acyclic diterpene glycosides from the aerial parts of paprika and pimiento

Paprika and pimiento are used as vegetables and spices. We have obtained three new acyclic diterpene glycosides, called capsianosides XVII (1), V methyl ester (2) and XIV (3) together with capsianosides I and II from the aerial parts of paprika and pimiento. The structures of these compounds have been established by (1)H- and (13)C-NMR spectra and two-dimensional NMR methods.     

Two new cycloartane glycosides from the underground parts of Aquilegia vulgaris

Two new cycloartane glycosides, named aquilegiosides K and L, have been isolated from the dried underground parts of Aquilegia vulgaris. Their structures were determined by two dimensional (2D) NMR spectroscopic analysis and chemical evidence.     

One-Step Synthesis of Cyclobutene-Annulated Fullerenes through a Cascade Reaction

The physicochemical properties of fullerene-based materials typically vary depending on the type and mode of addition of functional groups; therefore, developing fullerene derivatives with novel structures is imperative for further progress in materials science. In this study, we develop an efficient one-step strategy for synthesizing cyclobutene-annulated fullerene derivatives (cyclobutenofullerenes) and characterize their electronic properties. Despite the steric strain, cyclobutenofullerenes can be easily prepared via a one-step reaction of C₆₀ with a secondary propargylic phosphate. Structural analysis of the reaction intermediates suggests that the cascade reaction proceeds through a formal [2+2] cycloaddition of C₆₀ with an allene, caused by the 1,3-migration of the propargylic phosphate, followed by an additional 1,3-migration and the subsequent 1,2-elimination of the phosphodiester moiety.     

Oxidative Annulation of Arenecarboxylic and Acrylic Acids with Alkynes under Ambient Conditions Catalyzed by an Electron‐Deficient Rhodium(III) Complex

It has been established that an electron‐deficient Cp^E rhodium(III) complex catalyzes the oxidative [4+2] annulation of substituted arenecarboxylic and acrylic acids with alkynes under ambient conditions (at RT–40 °C, under air) without using excess amounts of substrates to produce the corresponding substituted isocoumarins and α‐pyrones in high yields. Minor modification of reaction conditions depending on the coordination ability of alkynes realized the high efficiency.     

A chemiluminescence biochemical oxygen demand measuring method

A new chemiluminescence biochemical oxygen demand (BOD_CL) determining method was studied by employing redox reaction between quinone and Baker's yeast. The measurement was carried out by utilizing luminol chemiluminescence (CL) reaction catalyzed by ferricyanide with oxidized quinone of menadione, and Saccharomyces cerevisiae using a batch-type luminometer. In this study, dimethyl sulfoxide was used as a solvent for menadione. After optimization of the measuring conditions, the CL response to hydrogen peroxide in the incubation mixture had a linear response between 0.1 and 100 μM H₂O₂ (r² = 0.9999, 8 points, n = 3, average of relative standard deviation; R.S.D._av = 4.22%). Next, a practical relationship between the BOD_CL response and the glucose glutamic acid concentration was obtained over a range of 11-220 mg O₂ L⁻¹ (6 points, n = 3, R.S.D._av 3.71%) with a detection limit of 5.5 mg O₂ L⁻¹ when using a reaction mixture and incubating for only 5 min. Subsequently, the characterization of this method was studied. First, the BOD_CL responses to 16 pure organic substances were examined. Second, the influences of chloride ions, artificial seawater, and heavy metal ions on the BOD_CL response were investigated. Real sample measurements using river water were performed. Finally, BOD_CL responses were obtained for at least 8 days when the S. cerevisiae suspension was stored at 4 °C (response reduction, 69.9%; R.S.D. for 5 testing days, 18.7%). BOD_CL responses after 8 days and 24 days were decreased to 69.9% and 35.8%, respectively, from their original values (R.S.D. for 8 days involving 5 testing days, 18.7%).     

Polymers with double-decker and side-opened cage silsesquioxanes: Effects of cage structures on materials properties

Cage silsesquioxanes, also known as polyhedral oligomeric silsesquioxanes (POSS), serve as crucial building blocks in crafting precisely designed organic–inorganic hybrid materials, given that their well-defined silsesquioxane clusters can be adorned with organic substituents. While polymers with POSS in their main chains have been thoroughly examined, analyzing the correlation between cage structure and material properties in main-chain-type polymers remains challenging. This difficulty stems from the limited range of organic substituents on traditional POSS monomers, thereby precluding comparisons between polymers with unified substituents and different cage structures. In this study, we synthesized double-decker silsesquioxane (DDSQ) and side-opened POSS (SO-POSS) monomers, both featuring phenyl groups. Subsequent platinum-catalyzed hydrosilylation polymerization yielded main-chain-polymers. Both the cage and linker structures influence thermal stability and the glass transition temperature, while the hardness was primarily determined by the linker structure. This research is the first to elucidate the impact of cage structure on the material properties of main-chain-type POSS polymers.     

Ends free and self-quenched molecular beacon with pyrene labeled pyrrolocytidine in the middle of the stem

Pyrene labeled pyrrolocytidine was incorporated into an oligonucleotide to construct ends free and self-quenched molecular beacon in which the fluorophore containing pyrrolocytidine was placed in the middle of the stem and used for the detection of a target DNA with an excellent efficiency.     

Two new 15-deoxycimigenol-type and three new 24-epi-cimigenol-type glycosides from Cimicifuga Rhizome

Two new 15-deoxycimigenol-type (1, 2) and three new 24-epi-cimigenol-type glycosides (3-5) were isolated from Cimicifuga Rhizome, and the structures were elucidated on the basis of spectroscopic data including 2D NMR spectra and chemical evidence. The two new 15-deoxycimigenol-type glycosides were the first cimigenol-type glycosides lacking a hydroxyl group at C-15.     

Chiral magnetic effect without chirality source in asymmetric Weyl semimetals

We describe a new type of the chiral magnetic effect (CME) that should occur in Weyl semimetals (WSMs) with an asymmetry in the dispersion relations of the left- and right-handed (LH and RH) chiral Weyl fermions. In such materials, time-dependent pumping of electrons from a non-chiral external source can generate a non-vanishing chiral chemical potential. This is due to the different capacities of the LH and RH chiral Weyl cones arising from the difference in the density of states in the LH and RH cones. The chiral chemical potential then generates, via the chiral anomaly, a current along the direction of an applied magnetic field even in the absence of an external electric field. The source of chirality imbalance in this new setup is thus due to the band structure of the system and the presence of (non-chiral) electron source, and not due to the parallel electric and magnetic fields. We illustrate the effect by an argument based on the effective field theory, and by the chiral kinetic theory calculation for a rotationally invariant WSM with different Fermi velocities in the left and right chiral Weyl cones; we also consider the case of a WSM with Weyl nodes at different energies. We argue that this effect is generically present in WSMs with different dispersion relations for LH and RH chiral Weyl cones, such as SrSi₂ recently predicted as a WSM with broken inversion and mirror symmetries, as long as the chiral relaxation time is much longer than the transport scattering time.