4-(t-butylthio)-3-buten-2-one. Synthon for α,β- and α,β,γ,δ-unsaturated aldehyde synthesis

A convenient synthesis of α,β- and α,β,γ,δ-unsaturated aldehydes using readily accessible 4-(t-butylthio)-3-buten-2-one as synthon was described.     

Practical, general, and systematic method for optical resolution of gem-dihalo- and monohalocyclopropanecarboxylic acids utilizing chiral 1,1'-binaphtholmonomethyl ethers: application to the synthesis of three chiral pesticides

We performed an efficient practical and systematic optical resolution method for gem-dihalo- and monohalocyclopropanecarboxylic acids and utilizing chiral 1,1'-binaphthol monomethyl ether (R)- as the key auxiliary. Direct esterification of with (R)- gave two 1R- and 1S-diastereomeric esters with marked different R(f) values, both of which were easily separated using simple column chromatography. Monodehalogenation of separated chiral esters using t-BuMgCl and cat. Co(dppe)(2)Cl(2) gave two 1,2-trans- and 1,2-cis-diastereomers with markedly different R(f) values, both of which were similarly separated using simple column chromatography. The obtained diastereomers and were easily hydrolyzed to the desired enantiopure acids (>99%) and (>99%), respectively, with recovery of (R)-, both in good to excellent yields. Utilizing the present method, important chiral agrochemicals, carpropamid and fencyclate , were readily synthesized. Pyrethroid with three asymmetric centers was efficiently synthesized in a much better yield compared with the reported method.     

Dual chromophore-nitroxides: novel molecular probes, photochemical and photophysical models and magnetic materials

Over the last decades scientists have faced growing requirements in novel methods of fast and sensitive analysis of antioxidant status of biological systems, spin redox probing and spin trapping, investigation of molecular dynamics, and of convenient models for studies of photophysical and photochemical processes. In approaching this problem, methods based upon the use of dual chromophore-nitroxide (CN) compounds have been suggested and developed. A CN consists of two molecular sub-functionality (a chromophore and a stable nitroxide radical) tethered together by spacers. In the dual compound the nitroxide is a strong intramolecular quencher of the fluorescence from the chromophore fragment. Reduction to hydroxylamine, oxidation of the nitroxide fragment or addition of an active radical yield the fluorescence increase and the parallel decay of the fragment electron spin resonance (ESR) signal. At certain conditions the dual molecules undergo photomagnetic switching and form excited state multi-spin systems. These unique properties of CN were intensively exploited as the basis for several methodologies, which include molecular probing, modeling intramolecular photochemical and photophysical processes, and construction of new magnetic materials.     

Red light in chemiluminescence and yellow-green light in bioluminescence: color-tuning mechanism of firefly, Photinus pyralis, studied by the symmetry-adapted cluster-configuration interaction method

The yellow-green luminescence from firefly luciferase has long been understood to be the emission from enol-oxyluciferin. However, a recent experiment showed that an oxyluciferin constrained to the keto form produced a yellow-green emission in luciferase (Branchini, B. R.; Murtiashaw, M. H.; Magyar, R. A.; Portier, N. C.; Ruggiero, M. C.; Stroh, J. G. J. Am. Chem. Soc. 2002, 124, 2112-2113). The present quantum mechanical/molecular mechanical and symmetry-adapted cluster-configuration interaction (SAC-CI) theoretical study supports the keto-form to be the yellow-green bioluminescence state in luciferase. We give the theoretically optimized structure of the excited state of oxyluciferin within luciferase, which gives luminescence calculated by the SAC-CI method that is close to the experimental value. Coulombic interactions with neighboring residues, in particular Arg218 and the phosphate group of AMP, play important roles in the color-tuning mechanism. Transformation to the enol form is energetically unfavorable in the luciferase environment. The twisted intramolecular charge-transfer (TICT) state is meta stable and would be easily relaxed to the co-planer structure. Further analyses were performed to verify the spectral-tuning mechanism based on the protonation state and the resonance structure of oxyluciferin.     

Solving the Schrodinger equation for helium atom and its isoelectronic ions with the free iterative complement interaction (ICI) method

The Schrodinger equation was solved very accurately for helium atom and its isoelectronic ions (Z=1-10) with the free iterative complement interaction (ICI) method followed by the variational principle. We obtained highly accurate wave functions and energies of helium atom and its isoelectronic ions. For helium, the calculated energy was -2.903,724,377,034,119,598,311,159,245,194,404,446,696,905,37 a.u., correct over 40 digit accuracy, and for H(-), it was -0.527,751,016,544,377,196,590,814,566,747,511,383,045,02 a.u. These results prove numerically that with the free ICI method, we can calculate the solutions of the Schrodinger equation as accurately as one desires. We examined several types of scaling function g and initial function psi(0) of the free ICI method. The performance was good when logarithm functions were used in the initial function because the logarithm function is physically essential for three-particle collision area. The best performance was obtained when we introduce a new logarithm function containing not only r(1) and r(2) but also r(12) in the same logarithm function.     

Self-assembled MnN superstructure

Self-assembled MnN nanoislands have been prepared on Cu(001) substrate. The nanoislands show a square shape and a well-defined size. They are regularly arrayed with a periodicity of (3.5+/-0.1) nanometer and form a two-dimensional square superstructure. The MnN island superstructure is stabilized by a short-range mechanism. A structural model has been proposed to explain the self-assembly and the high quality of the superstructure.     

Spin disorder and order in quasi-2D triangular Heisenberg antiferromagnets: comparative study of FeGa2S4, Fe2Ga2S5, and NiGa2S4

Our single crystal study reveals that the single-layer S=2 triangular Heisenberg antiferromagnet FeGa2S4 forms a frozen spin-disordered state, similar to the S=1 isostructural magnet NiGa2S4. In this state, the magnetic specific heat C{M} is not only insensitive to the field, but shows a T2 dependence that scales to C{M} of NiGa2S4, suggesting the same underlying mechanism of the 2D coherent behavior. In contrast, the bilayer system Fe2Ga2S5 exhibits a 3D antiferromagnetic order.     

Thermosensitive Ion Channel Activation in Single Neuronal Cells by Using Surface‐Engineered Plasmonic Nanoparticles

Controlling cell functions using external photoresponsive nanomaterials has enormous potential for the development of cell‐engineering technologies and intractable disease therapies, but the former currently requires genetic modification of the target cells. We present a method using plasma‐membrane‐targeted gold nanorods (pm‐AuNRs) prepared with a cationic protein/lipid complex to activate a thermosensitive cation channel, TRPV1, in intact neuronal cells. Highly localized photothermal heat generation mediated by the pm‐AuNRs induced Ca²⁺ influx solely by TRPV1 activation. In contrast, the use of previously reported cationic AuNRs that are coated with a conventional synthetic polymer also led to photoinduced Ca²⁺ influx, but this influx resulted from membrane damage. Our method provides an optogenetic platform without the need for prior genetic engineering of the target cells and might be useful for novel TRPV1‐targeted phototherapeutic approaches.     

Nonequilibrium solvation for vertical photoemission and photoabsorption processes using the symmetry-adapted cluster-configuration interaction method in the polarizable continuum model

In this paper, we present the theory and implementation of a nonequilibrium solvation model for the symmetry-adapted cluster (SAC) and symmetry-adapted cluster-configuration interaction (SAC-CI) method in the polarizable continuum model. For nonequilibrium solvation, we adopted the Pekar partition scheme in which solvent charges are divided into dynamical and inertial components. With this nonequilibrium solvation scheme, a vertical transition from an initial state to a final state may be described as follows: the initial state is described by equilibrium solvation, while in the final state, the inertial component remains in the solvation for the initial state; the dynamical component will be calculated self-consistently for the final state. The present method was applied to the vertical photoemission and absorption of s-trans acrolein and methylenecyclopropene. The effect of nonequilibrium solvation was significant for a polar solvent.