Synthesis and characterization of dinuclear late transition-metal (copper(I), silver(I), rhenium(I)) complexes with a bis-pyridylimine ligand linked by S–S bonding

Two dinuclear complexes with novel coordination type, [Cu₂(DPDIDT)₂](PF₆)₂ (1) and [Ag₂(DPDIDT)₂](BF₄)₂ (2), plus a dinuclear complex of the usual coordination type, {Re(Cl)(CO)₃}₂(DPDIDT) (3) as a comparative complex were prepared from bis-(4-(2-pyridylmethyleneiminophenyl))disulfide (DPDIDT) and the relevant metal sources. Complexes (1) and (2) exist in solution as dimer structures of the square-pole type according to the interpretation of the ESI mass and ¹H NMR spectra. The density functional theory calculations for the monomer and dimer models of the Cu(I) complex cations, [Cu_n(DPDIDT)_n]ⁿ⁺ (n = 1, 2), demonstrated that the dimer form is structurally more stable than the monomer form. The UV–Vis absorption spectra of complexes (1) and (3) both exhibit a typical MLCT absorption band in the 400–700 nm region. The Re(I) complex (3) was revealed to possess a facial configuration with respect to the three carbonyl ligands by ¹H NMR and IR data.     

Total syntheses of cyclitol based natural products from myo-inositol: brahol and pinpollitol

Inositol and their derivatives are important class of biologically active natural products. Among the nine theoretically possible inositols, six are known to occur in nature. Interestingly one or more methyl ethers of these inositols have been isolated from plants and these methyl inositols are presumed to have important functions in plant biology. Brahol and pinpollitol are two naturally occurring methylated inositols reported to have allo-inositol and chiro-inositol configurations, respectively. Adopting our sulfonate inversion strategies for synthesizing protected chiro- and allo-inositols from cheaply available myo-inositol in combination with new methods we have achieved the total syntheses of these methylated inositols. The proposed structure of brahol has been synthesized in six steps from myo-inositol. We have not only disproved the proposed structure of brahol but also established its correct structure. Also, we have efficiently synthesized pinpollitol and its positional isomer from myo-inositol. These works involve several selective protection-deprotection strategies of inositol hydroxyl groups.     

The Crossover Regime for the Weakly Asymmetric Simple Exclusion Process

We consider the asymmetric simple exclusion process in one dimension with weak asymmetry (WASEP) and 0–1 step initial condition. Our interest are the fluctuations of the time-integrated particle current at some prescribed spatial location. One expects a crossover from Gaussian to Tracy-Widom distributed fluctuations. The appropriate crossover scale is an asymmetry of order \(\sqrt{\varepsilon}\), times of order ε ^?2, and a spatial location of order ε ^?3/2. For this parameter window we obtain the limiting distribution function of the integrated current in terms of an integral over the difference of two Fredholm determinants. For large times, on the scale ε ^?2, this distribution function converges to the one of Tracy-Widom.     

Complete reducibility,Külshammer’s question,conjugacy classes: A D4 example

Let k be a nonperfect separably closed field. Let G be a connected reductive algebraic group defined over k. We study rationality problems for Serre’s notion of complete reducibility of subgroups of G. In particular, we present a new example of subgroup H of G of type D₄ in characteristic 2 such that H is G-completely reducible but not G-completely reducible over k (or vice versa). This is new: all known such examples are for G of exceptional type. We also find a new counterexample for Külshammer’s question on representations of finite groups for G of type D₄. A problem concerning the number of conjugacy classes is also considered. The notion of nonseparable subgroups plays a crucial role in all our constructions.     

Thermodynamics for the Formation of Double‐Stranded DNA–Single‐Walled Carbon Nanotube Hybrids

For the first time, the thermodynamics are described for the formation of double‐stranded DNA (ds‐DNA)–single‐walled carbon nanotube (SWNT) hybrids. This treatment is applied to the exchange reaction of sodium cholate (SC) molecules on SWNTs and the ds‐DNAs d(A)₂₀–d(T)₂₀ and nuclear factor (NF)‐κB decoy. UV/Vis/near‐IR spectroscopy with temperature variations was used for analyzing the exchange reaction on the SWNTs with four different chiralities: (n,m)=(8,3), (6,5), (7,5), and (8,6). Single‐stranded DNAs (ss‐DNAs), including d(A)₂₀ and d(T)₂₀, are also used for comparison. The d(A)₂₀–d(T)₂₀ shows a drastic change in its thermodynamic parameters around the melting temperature (T_m) of the DNA oligomer. No such T_m dependency was measured, owing to high T_m in the NF‐κB decoy DNA and no T_m in the ss‐DNA.