Observable seesaw and its collider signatures

We discuss the scenario with TeV-scale right-handed neutrinos, which are accessible at future colliders, while holding down tiny seesaw-induced masses and sizable couplings to the standard-model particles. The signal with tri-lepton final states and large missing transverse energy is appropriate for studying collider signatures of the scenario with extra spatial dimensions. We show that the LHC experiment generally has a potential to discover the signs of extra dimensions and the origin of small neutrino masses.     

Contributions from the indirect ionic interactions to the elastic constants in the rock-salt structure crystals

Under the harmonic approximation, the contributions from the indirect ionic interactions to the elastic constants are calculated for the alkali halide and silver halide crystals with the rock-salt structure. The coupling constants of the indirect ionic interactions are calculated by the self-consistent field treatment of the local density approximation and the spherical solid model. The calculated values of the coupling constants are large for the silver ion. The indirect ionic interaction significantly affects the elastic constants. It quantitatively explains the deviation from the Cauchy relation in alkali halide crystals. Moreover, it provides a clear account for the large values of the deviation from the Cauchy relation in AgCl and AgBr.     

Application of the Perimeter Model to the Assignment of the Electronic Absorption Spectra of Gold(III) Hexaphyrins with [4n+2] and [4n] π‐Electron Systems

Expanded porphyrins : The electronic excited states of two forms of meso‐hexakis(pentafluorophenyl)‐substituted gold(III) hexaphyrin(1.1.1.1.1.1), such as that depicted, have been investigated by density functional calculations and magnetic circular dichroism spectroscopy to assign their low‐energy excited singlet states.

     

Polymer micelles from tadpole-shaped amphiphilic block-graft copolymers prepared by “Grafting-through” ATRP

A series of tadpole-shaped block-graft amphiphilic copolymers, i.e., block copolymers consisting of a cylindrical hydrophilic brush block and a coiled hydrophobic block were synthesized using “grafting-through” atom transfer radical polymerization. A tadpole-shaped block-graft copolymer from polystyrene bromide and a methacryloyl-terminated poly(tert-butyl acrylate) was prepared first. Then, hydrolysis of the poly(tert-butyl acrylate) side chains to polyacrylic acid side chains provided tadpole-shaped block-graft amphiphilic copolymers, which formed pH responsive micelles in water, the latter being confirmed by dynamic light scattering and atomic force microscopy.     

Palladium-catalyzed direct N-arylation of nucleosides, nucleotides, and oligonucleotides for efficient preparation of dG-N2 adducts with carcinogenic amino-/nitroarenes

A method for direct palladium-catalyzed N-arylation reaction of nucleobases was developed for the convenient synthesis of DNA adducts with carcinogenic compounds. Using xantphos as the phosphine ligand and tetraethylammonium fluoride as the base in DMSO, several o-iodonitroarenes could be efficiently coupled with 2'-deoxyguanosine, 2'-deoxyadenosine, and 2'-deoxycytidine. The presence of a 3'-phosphate group in the deoxyribose moiety was found to be compatible with this N-arylation reaction; further, oligonucleotides could serve as substrates. The facile nitroreduction of the coupling compounds (12) yielded 2'-deoxyguanosin-N2-ylarylamine adducts, which are known to be biologically important. Compound 12 was easily converted to phosphoramidite derivatives, allowing the preparation of site-specific modified oligonucleotides with arylamine after the nitroreduction.     

Sokodosides, steroid glycosides with an isopropyl side chain, from the marine sponge Erylus placenta

Two novel steroid glycosides, sokodosides A and B (1 and 2, respectively), were isolated from the marine sponge Erylus placenta as growth-inhibitory principles against several strains of yeast and a cancer cell line. Sokodosides possess the novel carbon skeleton as characterized by the presence of a combination of isopropyl side chain and the 4,4-dimethyl steroid nucleus. Sokodoside B has another unique characteristic in the presence of delta(8,14,16) unsaturation. The structures of sokodosides were determined by analysis of spectral data and chemical degradation. The absolute stereochemistry of sokodoside A (1) was determined by the application of the modified Mosher analysis to the aglycon obtained by acid hydrolysis, whereas the absolute stereochemistry of the monosaccharide units in 1 and 2 was determined by chiral GC analyses of the acid hydrolysates.     

Bismuth-catalyzed intermolecular hydroamination of 1,3-dienes with carbamates, sulfonamides, and carboxamides

A Bi(OTf)(3)/Cu(CH(3)CN)(4)PF(6) system efficiently promoted intermolecular 1:1 hydroamination of 1,3-dienes with various carbamates, sulfonamides, and carboxamides to afford allylic amines in good yield (up to 96%). Reaction proceeded with 0.5-10 mol % catalyst loading at 25-100 degrees C (generally at 50 degrees C) in 1,4-dioxane within 24 h. The Bi(OTf)(3)/Cu(CH(3)CN)(4)PF(6) system constitutes a new entry into series of intermolecular hydroamination catalysis. Mechanistic studies and the postulated reaction mechanism are also discussed.     

Experimental evidence and bond characterization of a cyclopropenylgermylene

The reduction of p-anisyl(1,2,3-tri-tert-butylcycloprop-2-en-1-yl)dichlorogermane (1) with potassium in the presence of an excess of tert-butyldimethylsilane in benzene under reflux gave p-anisyl(tert-butyldimethylsilyl)(1,2,3-tri-tert-butylcycloprop-2-en-1-yl)germane (4) in 15% yield. The formation of 4 indicates that p-anisyl(1,2,3-tri-tert-butylcycloprop-2-en-1-yl)germylene (2), which is the first example of a (cycloprop-2-en-1-yl)germylene derivative, was generated and trapped by the hydrosilane. The DFT calculations revealed that the cis-2-p-anisyl-1,3,4-tri-tert-butyl-2-germabicyclo[1.1.0]butane-2,4-diyl structure cis-5 is 8.0 kJ/mol more stable than cis-2. The NBO analysis revealed that cis-5 has a 2-germabicyclo[1.1.0]butane diradical character.     

Design of new bidentate ligands constructed of two Hoechst 33258 units for discrimination of the length of two A3T3 binding motifs

[structure: see text] The aim of this study is to develop bidentate minor-groove binders that bind the double binding motifs cooperatively. The new bidentate ligands (1) have been designed by connecting two Hoechst 33258 units with a polyether linker for cooperative binding with two remote A3T3 sites of DNA. The linker is introduced to the benzimidazole ring so that it is located at the convex side of the Hoechst unit. DNA binding affinity of the ligands was evaluated by measuring surface plasmon resonance (SPR), circular dichroism, and fluorescence spectra. Interestingly, the bidentate ligands (1) did not show affinity to DNA1 with a single A3T3 motif but showed selective affinity to DNA2 with two A3T3 motifs. The Long Bis-H (1L) having a long polyether linker showed specific binding to DNA2(6) with two A3T3 motifs separated by six nonbinding base pairs. The Long Bis-H (1L) has also shown specific binding to the three-way junction DNA4 with two A3T3 motifs. This study has demonstrated that DNA with double binding motifs can be selectively recognized by the newly designed bidentate ligands.