Chiroptical transcription of helical information through supramolecular harmonization with dynamic helices

With biologically important "peptide bundling" as the motif, new chromophoric cyclic host 1 was designed, which consists of two zinc porphyrin units that are connected by dynamic peptide helices of nonameric aminoisobutyric acid (Aib) units. Upon inclusion of pyridine-anchored helical peptides between the zinc porphyrin units, 1 displayed an intense exciton-coupled circular dichroism (CD) band at 410-450 nm, whose sign reflected the helical sense of the guest peptides. Studies with conformationally defined dehydrophenylalanine-containing analogues indicated that the dynamic helical chains in the host are stereochemically harmonized with right- or left-handed helices of the guest peptides in a confined nano space, leading to either clockwise- or anticlockwise-twisted geometry (chiroptical output) of the connecting zinc porphyrin chromophores.     

Parviflorenes B-F, novel cytotoxic unsymmetrical sesquiterpene-dimers with three backbone skeletons from Curcuma parviflora

Five novel natural products classified as dimeric sesquiterpenes, named parviflorenes B-F (2-6), possessing three types of novel backbone frameworks, have been isolated from Curcuma parviflora (Zingiberaceae). The structures of 2-6 were elucidated by means of spectroscopic studies, and the structure of 2 was further unambiguously established by X-ray crystallographic analysis. Compounds 2, 4, and 6 have an unsymmetrical bis-cadinane skeleton, while compound 3 is a dimer of cadinane and iso-cadinane, and compound 5 possesses another novel carbon framework consisting of two cadinanes with different bond-connection. These new compounds with novel carbon skeletons showed cytotoxicity against tumor cell lines.     

Self-assembly of a pi-electronic amphiphile consisting of a zinc porphyrin-fullerene dyad: formation of micro-vesicles with a high stability

An amphiphilic zinc porphyrin-fullerene dyad appended with triethyleneglycol chains in aqueous media forms uniformly-sized multilamellar vesicles with a mean diameter of 100 nm that are thermally stable and robust against membrane lysis with surfactants.     

Discotic liquid crystals stabilized by interionic interactions: imidazolium ion-anchored paraffinic triphenylene

Incorporation of imidazolium ion functionalities into the paraffinic side-chain termini of a triphenylene derivative resulted in stabilization of a columnar mesophase of its liquid crystalline assembly, which was retained over a wider temperature range down to 4 degrees C by an externally added imidazolium-based ionic liquid.     

Simultaneous determination of In(III) and Cd(II) by differential pulse polarography in the presence of poly β-cyclodextrin

The difference in the peak potentials of In(III) and Cd(II), whose reduction potentials are very close to each other, becomes large in the presence of poly beta-cyclodextrin in sodium perchlorate medium. The relationships between the peak currents for these two ions and their concentrations are linear, suggesting that the simultaneous determination of the ions is possible in the presence of this reagent.     

Resistance fluctuations in integer quantum-Hall transitions

We have studied the resistance fluctuations (RF) in integer quantum-Hall transitions for high-mobility two-dimensional electron gas systems. The role of coherence in RF is examined by investigating the conductance through two scattering regions, that are spatially separated but interfere quantum-mechanically with each other. The phase coherence does not play a substantial role in determining the pattern of RF, whereas it affects the amplitude of RF.     

Transition-metal-free controlled polymerization for poly(p-aryleneethynylene)s

A transition-metal-free controlled polymerization for the attainment of poly(p-aryleneethynylene)s is developed. The polymerization of 1-pentafluorophenyl-4-[(trimethylsilyl)ethynyl]benzene with a catalytic amount of fluoride anions proceeds in a chain-growth-like manner to afford polymers with controlled molecular weights and low polydispersity indexes. The mechanism involves a pentacoordinated fluorosilicate as a key intermediate. The anionic “living” nature of this process is applied to block copolymerization and also surface-terminated polymerization.     

Lateral capillary forces between solid bodies on liquid surface: a lattice Boltzmann study

When two solid bodies are placed on the surface of a dense liquid under gravitation, they deform the liquid surface to experience a lateral capillary force between themselves that can be attractive and repulsive, depending on the wettabilities and weights of the bodies. In the present study, the lateral capillary force between two square bodies at a liquid-vapor interface has been examined using numerical simulations based on a two-dimensional two-phase lattice Boltzmann (LB) method. The particular situations were simulated, where every body was vertically constrained and had the fixed triple points at its upper or lower corners. Here, the triple point indicates the place at which vapor, liquid, and solid phases meet. The interaction force between these two bodies was calculated as a function of the separation distance, the interfacial tension, and the gravitational acceleration. The simulation results agree well with the analytical expression of the lateral capillary interaction, indicating that our LB method can reproduce the interaction force between two bodies of various wettabilities at a liquid-vapor interface in mechanical equilibrium.