Synthesis and tautomeric behavior of 3-(pyrazolylhydrazonomethyl)-2-oxo-1, 2-dihydroquinoxalines. Specification of hydrazone imine and diazenyl enamine forms

3-(Pyrazolylhydrazonomethyl)-2-oxo-1, 2-dihydroquinoxalines were synthesized, and their tautomer ratios between hydrazone imine and diazenyl enamine forms were specified by pmr spectral data.     

Diarylurea-linked zinc porphyrin dimer as a dual-mode artificial receptor: supramolecular control of complexation-facilitated photoinduced electron transfer

A novel porphyrinic receptor 1 in which two zinc porphyrins are bridged by two diarylurea linkers was developed for recognition of a viologen derivative (hexyl viologen, HV). The electronic absorption spectra as well as the 1H NMR experiments revealed that the HV molecule was bound to the cleft in 1 mainly through carbonyl dipole-charge interactions to afford a 1:1 complex. From the steady-state fluorescence spectroscopic study, the photoinduced electron transfer (PET) from 1 to HV was extremely facilitated by the receptor-substrate complexation. The receptor 1 also formed a 1:1 complex with 1,4-diazabicyclo[2.2.2]octane (DABCO) through two Zn-N coordination interactions, and, using DABCO as an inhibitor, we suppressed the PET reaction via the substrate exchange.     

Novel synthesis of zerumbone-pendant derivatives and their biological activity

Zerumbone 1, having powerful latent reactivity and containing two conjugated double bonds and a double conjugated carbonyl group is the major component of the essential oil of wild ginger, Zingiber zerumbet Smith. The conjugation system plays an important role in the expression of biological activity. N-Bromosuccinimide (NBS) reaction of 1 gave high reactive intermediate 2 with an exo-methylene group, which was obtained from 1 quantitatively. Treatment of 2 with nucleophiles gave various zerumbone-pendant derivatives, including C–H, C–O, C–N, and C–C bond formation, maintaining the conjugation system through S_N2′-type reaction. Almost all zerumbone-pendant derivatives showed a good value of IC₅₀ against the suppressive effect of NO generation. Among them, amine derivative 5, binding with 2 mol of zerumbone, showed the strongest activity (IC₅₀: 0.24 μM).     

Synthesis and characterization of new aromatic liquid crystalline polyesters having phenyl substituents

Two different series of new aromatic liquid crystalline (LC) polyesters were prepared from 3-phenyl-4, 4'-biphenyldicarboxylic acid (PBDA) and 1-phenyl-2, 6-naphthalenedicarboxylic acid (PNDA). PBDA and PNDA were polymerized with various aromatic diols such as hydroquinone, substituted hydroquinones, isomeric naphthalenediols and 4, 4'-biphenol, and the resulting polyesters were characterized by DSC, WAXD, and on a cross-polarizing microscope for the study of their thermal transition and crystallization properties, and mesophases formed therefrom.     

Age-dependent plasticity in the superior temporal sulcus in deaf humans: a functional MRI study

Background  

Sign-language comprehension activates the auditory cortex in deaf subjects. It is not known whether this functional plasticity in the temporal cortex is age dependent. We conducted functional magnetic-resonance imaging in six deaf signers who lost their hearing before the age of 2 years, five deaf signers who were >5 years of age at the time of hearing loss and six signers with normal hearing. The task was sentence comprehension in Japanese sign language.     

A possible interpretation of CDF dijet mass anomaly and its realization in supersymmetry

Recently, the CDF Collaboration reports an anomaly in dijet mass distribution in association with a lepton and missing energy. We discuss a possibility that the origin of the lepton and missing energy comes not from a W boson but a new boson particle, which is also responsible for the dijet mass peak. We show that such a situation can be realized in the framework of the minimal supersymmetric standard model and the dijet anomaly can be explained.     

Magnetic properties of H+ implanted bubble garnet films by means of depth selective conversion electron Mössbauer spectroscopy

Bubble garnet films before and after 50 keV H⁺ implantation have been studied by means of DCEMS. The spintilt angle of the films as grown after etching off 1000 å was measured to be 30±2? relative to the surface normal at the top of the surface. The doses of implanted H⁺ ions were 2, 4 and 8×10¹⁶ ions/cm². Mössbauer spectra were measured after successive etching of the implanted layer. The magnetic hyperfine field was obtained as a function of depth. The implanted hydrogen distribution was also measured by the¹H(¹⁵N, αγ)¹²C reaction.     

A Catalyst‐Free Amination of Functional Organolithium Reagents by Flow Chemistry

Reported is the electrophilic amination of functional organolithium intermediates with well‐designed aminating reagents under mild reaction conditions using flow microreactors. The aminating reagents were optimized to achieve efficient C?N bond formation without using any catalyst. The electrophilic amination reactions of functionalized aryllithiums were successfully conducted under mild reaction conditions, within 1 minute, by using flow microreactors. The aminating reagent was also prepared by the flow method. Based on stopped‐flow NMR analysis, the reaction time for the preparation of the aminating reagent was quickly optimized without the necessity of work‐up. Integrated one‐flow synthesis consisting of the generation of an aryllithium, the preparation of an aminating reagent, and their combined reaction was successfully achieved to give the desired amine within 5 minutes of total reaction time.     

Depth selective conversion electron Mössbauer spectroscopy by use of a proportional counter

The depth selectivity of conversion electron Mössbauer spectroscopy by use of a proportional counter was studied in detail. For this purpose the pulse-height spectrum of conversion and Auger electrons emitted from a⁵⁷Fe absorber was measured at the resonance Doppler velocity. From the spectrum it is found that the energy settings of 2–5 keV, 6–9 keV and 11–14 keV are suitable for depth selective analysis.     

Preferable tautomer of dihydropyrazolo[5, 1-c][1, 2, 4]triazines in solution

Dihydropyrazolo[5, 1-c][1, 2, 4]triazines 6, 7 and 8 were found to predominate as the 4, 6-dihydro tautomeric form in solution by the measurement of ID NOE different spectra.