Different Behavior of Density Perturbations Between Dayside and Nightside in the Martian Thermosphere and the Ionosphere Associated With Atmospheric Gravity Waves.

To investigate the excitation mechanism of ionospheric perturbations on Mars by the Neutral Gas and Ion Mass Spectrometer (NGIMS) onboard Mars Atmosphere and Volatile EvolutioN (MAVEN), we categorize ionospheric perturbations into three cases: (a) the ion-neutral coupling cases where ion and neutral perturbations are well coupled, (b) the ion-specific cases where ion perturbations move independently from neutrals, and (c) the coronal mass ejection cases associated with solar wind extreme events. A representative number of cases from total profiles are compared with a numerical model to determine the fraction that can be explained by an atmospheric gravity waves (GW). The neutral perturbations on the dayside at 170-190 km altitudes are in excellent agreement with the GW.

Spin dynamics in a Heisenberg weak antiferromagnetic chain of an iodide-bridged Cu(II) complex.

[Cu(chxn)I]I (chxn = 1,2-diaminocyclohexane) has been synthesized, which is the first report of an iodide-bridged Cu(II) chain structure. This chain compound shows = 1/2 Heisenberg weak antiferromagnetism ( = -0.3 cm) and magnetic relaxation ( = 43 ms at 1.

Tunable Synchronicity of Molecular Valence Tautomerism with Macroscopic Solid-Liquid Transition by Molecular Lattice Engineering.

The combination of a cobalt-dioxolene core that exhibits valence tautomerism (VT) with pyridine-3,5-dicarboxylic acid functionalized with chains bearing two, four, or six oxyethylene units led to new complexes ConEGEspy (n = 2, 4, and 6). These complexes commonly form violet crystals of the low-spin (ls)-[Co (nEGEspy) (3,6-DTBSQ)(3,6-DTBCat)] (ls-[Co ], 3,6-DTBSQ = 3,6-di-tert-butyl semiquinonato, 3,6-DTBCat = 3,6-di-tert-butyl catecholato). Interestingly, violet crystals of Co2EGEspy in the ls-[Co ] transitioned into a green liquid, accompanied by an almost complete VT shift (94 %) to the high-spin (hs)-[Co (nEGEspy) (3,6-DTBSQ) ] (hs-[Co ]) upon melting.

Nuclear Quantum Effect on the χ Band Shape of Vibrational Sum Frequency Generation Spectra of Normal and Deuterated Water Surfaces.

In the vibrational sum frequency generation (VSFG) spectrum of the air/water interface, there is an open question whether the imaginary spectrum of nonlinear susceptibility Im[χ] has a positive band in the low-frequency tail of the OH stretching band. We previously elucidated by molecular dynamics (MD) analysis of the VSFG spectrum that the positive band could arise from particularly strong hydrogen-bonded water pairs at the water surface. This mechanism should be emphasized in OD stretching in comparison to OH, because OD forms stronger hydrogen bonds.

Molecular dynamics study of structure and vibrational spectra at zwitterionoic lipid/aqueous KCl, NaCl, and CaCl solution interfaces.

Molecular dynamics (MD) simulations of KCl, NaCl, and CaCl solution/dipalmytoylphosphatidylcholine lipid interfaces were performed to analyze heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectra in relation to the interfacial water structure. The present MD simulation well reproduces the experimental spectra and elucidates a specific cation effect on the interfacial structure. The K, Na, and Ca cation species penetrate in the lipid layer more than the anions in this order, due to the electrostatic interaction with negative polar groups of lipid, and the electric double layer between the cations and anions cancels the intrinsic orientation of water at the water/lipid interface.

Magnetic Sponge with Neutral-Ionic Phase Transitions.

Phase transitions caused by the charge instability between the neutral and ionic phases of compounds, i.e., N-I phase transitions, provide avenues for switching the intrinsic properties of compounds related to electron/spin correlation and dipole generation as well as charge distribution.

Superazaporphyrins: meso-pentaazapentaphyrins and one of their low-symmetry derivatives.

Supersized: Three pentaazapentaphyrin derivatives, that is, the superazaporphyrins (SAzPs), as well as a superphthalocyanine (SPc) and a mixed low-symmetry derivative have been prepared and characterized. Decaaryl SAzPs have a distorted (4n+2) π structure and show the Q bands at about λ=840-880 nm. These compounds are relatively air stable.

Incommensurate modulation in the microporous silica SSZ-24.

A detailed investigation of the structure of microporous silica, SSZ-24, is presented. It is shown by X-ray powder diffraction and (29)Si MAS NMR experiments that the structure deviates from the previously proposed AlPO(4)-5-type structure. At room temperature, electron diffraction (ED) patterns exhibit extra diffraction spots, which can be attributed to an incommensurate structural modulation along the c axis.

Helical Chiral Polyisocyanides Possessing Porphyrin Pendants: Determination of Helicity by Exciton-Coupled Circular Dichroism.

Exciton-coupled circular dichroism of the porphyrin Soret band of triblock copolymers prepared from chiral isocyanide monomers and an achiral tetraphenylporphyrin derivative (TPP) provides a novel method for determining the helical sense of poly(aryl isocyanide)s (see the schematic representation of the structure).

The Fate of Bis(η -allyl)palladium Complexes in the Presence of Aldehydes (or Imines) and Allylic Chlorides: Stille Coupling versus Allylation of Aldehydes (or Imines).

The mere presence or absence of PPh suffices to control the reactivity of bis(η -allyl)palladium complexes. In the absence of PPh they undergo chemoselective allylic addition to aldehydes or imines, even in the presence of allylic chlorides, whereas in the presence of PPh the Stille coupling reaction takes place chemoselectively, even when aldehydes or imines are also present.

Do More Electrophilic Aldehydes/Ketones Exhibit Higher Reactivity toward Nucleophiles in the Presence of Lewis Acids?

A crucial role in the chemoselective synthesis of primary, secondary, and homoallylic alcohols and of Diels-Alder adducts is played by Lewis acids (LA) in the addition of nucleophiles (Nu) to carbonyl compounds (see scheme; EWG = electron-withdrawing group, EDG = electron-donating group).

A Direct and Efficient α-Selective Glycosylation Protocol for the Kedarcidin Sugar, L-Mycarose: AgPF as a Remarkable Activator of 2-Deoxythioglycosides.

The α-selective effect and potency of AgPF on readily prepared 2-deoxythioglycosides allows the direct attachment of a partially protected allo-sugar, such as L-mycarose, to an advanced and hindered aglycon unit of kedarcidin. This method also permits access to other 2-deoxyglycosides in an expedient and mild manner. PMBM=p-methoxybenzyloxymethyl, Alloc=allyloxycarbonyl, TES=triethylsilyl.