Organonickel(III) complexes

Paramagnetic organonickel(III) complexes, RNi(PPhMe₂)₂Br₂ (R = CCl₂=CCl or C₆Cl₅), have been prepared by the reaction of trans-RNi(PPhMe₂)₂Br with N-bromosuccinimide.     

Synthetic studies of psilocin analogs having either a formyl group or bromine atom at the 5- or 7-position

Psilocin analogs having either a formyl group (9-12) or a bromine atom (13-18) at the 5- or 7-position have been prepared for the first time. Syntheses of 5- and 7-bromo derivatives of 4-hydroxy- (23, 24, 28) and 4-benzyloxyindole-3-carbaldehyde (19, 25, 29, 30), 4-benzyloxyindole-3-acetonitriles (20, 31), and 4-benzyloxy-N,N-dimethyltryptamine (32, 34, 35) have also been established.     

Liquid Model of Phase Transition from Quark-Gluon Phase to Hadron Phase on Analogy of BCS Theory

A phenomenological model of the transition from quark-gluon phase to hadron phase is presented on the analogy of BCS theory. The massive current-quarks constitute the quark Cooper-pair, i.e., the hadron at T_c = 150~200 MeV, The order parameter of qq-pair takes a value in the range from 0.4 to 0.2 GeV. An experimental verification method of the present model in the heavy-ion collision is proposed.     

Communication: A concerted mechanism between proton transfer of Zundel anion and displacement of counter cation

Ab initio path integral molecular dynamics simulation of M(+)(H(3)O(2)(-)) (M = Li, Na, and K) has been carried out to analyze how the structure and dynamics of a low-barrier hydrogen-bonded Zundel anion, H(3)O(2)(-), can be affected by the counter alkali metal cation, M(+). Our simulation predicts that the quantum proton transfer in Zundel anion can be strongly coupled to the motion of counter cation located nearby. A smaller cation can induce larger structural distortion of the Zundel anion fragment making the proton transfer barrier higher, and hence, lower the vibrational excitation energy. It is also argued that a large H∕D isotope effect is present.     

Liquid‐Phase RNA Synthesis by Using Alkyl‐Chain‐Soluble Support

Recent progress in the RNA therapeutics has increased demand for the synthesis of large quantities of oligoribonucleotides. The assembly of RNA oligomers relies mainly on solid‐phase approaches. These allow rapid product purification and the ability to drive a target reaction to completion through the use of excess reagents. Despite the known advantages of solid‐phase synthesis, some issues in the process remain to be addressed, such as low and limited scale, reagent accessibility, and the use of a very large excess of reagents. Herein, we report a highly efficient and practical method of liquid‐phase synthesis of RNA oligomers by using alkyl‐chain‐soluble support. We demonstrate the utility of the liquid‐phase method through 21‐mer RNA synthesis on a gram scale.     

Polymerization of 2-Oxazolines. IV. The Structure and the Reactivity of 2-Substituted-2-oxazolines and Oxazolinium Perchlorates

Abstract

In order to elucidate the structure and the stability of the growing cationic end in the polymerization of 2-oxazolines, the reactions of 2-bromoethylbenzamide with silver salts such as silver perchlorate, tetrafluoroborate, nitrate, nitrite, cyanate, and acetate were investigated. The reactions with silver perchlorate and tetrafluoroborate gave the 2-phenyl-2-oxazolinium salt (intramolecular O-alkylation product) quantitatively, whereas the reaction with silver nitrate gave the corresponding alkyl nitrate (staight-chain product). For the reactions with silver nitrite, cyanate and acetate, both products were obtained. In order to elucidate the ring-opening reactivity of the oxazolinium cation, the ring-opening addition reaction of N-methyl-2-oxazolinium perchlorates with pyridine was investigated. It was found that N-methyl-2-phenyl-2-oxazolinium perchlorate was more reactive toward the nucleophilic ring-opening reaction than was N-methyl-2-methyl-2-oxazolinium perchlorate. The mutual copolymerization of 2-phenyl-2-oxazoline with the other 2-substituted-2-oxazoline such as 2-methyl-, 2-isopropyl-, and 2-benzyl-2-oxazoline indicated that the monomer reactivity ratio r₂ was much larger than unity, whereas r₁ was very much smaller. Based on these results, the influence of the structure and the reactivity of the monomer and the growing cationic end of the polymerizability of 2-oxazolines are discussed.     

Orbifold equivalence and the sign problem at finite baryon density

We point out that SO(2N(c)) gauge theory with N(f) fundamental Dirac fermions does not have a sign problem at finite baryon number chemical potential μ(B). One can thus use lattice Monte Carlo simulations to study this theory at finite density. The absence of a sign problem in the SO(2N(c)) theory is particularly interesting because a wide class of observables in the SO(2N(c)) theory coincide with observables in QCD in the large N(c) limit, as we show using the technique of large N(c) orbifold equivalence. We argue that the orbifold equivalence between the two theories continues to hold at finite μ(B) provided one adds appropriate deformation terms to the SO(2N(c)) theory. This opens up the prospect of learning about QCD at finite μ(B) using lattice studies of the SO(2N(c)) theory.     

Fabrication and electrochemical instrumentation of redox‐active nanofiber mat for polyaniline incorporated with poly(imide sulfonate)

In this study, we demonstrate the fabrication of an electrochemically active nanofiber mat that is a composite of high‐performance poly(imide sulfonate) (PIS) and polyaniline (PANI). First, a nonconductive nanofiber mat comprising nanofibers having diameters of ca. 300 nm was fabricated by the electrospinning of ionomeric PIS in N,N‐dimethylformamide (DMF). Then, the nanofibers were modified using PANI, which was synthesized by the oxidative polymerization of aniline, yielding an electrochemically active nanofiber mat having a diameter of ca. 350 nm. It was confirmed that PANI was successfully incorporated onto the PIS nanofiber mats by X‐ray photoelectron spectroscopy. Subsequently, we conducted electrochemical measurements of the PANI‐modified nanofiber mats using a tailor‐made attachment in which the working electrode gently comes in contact with the nanofiber mat surface. This attachment was observed to be widely useful in the cyclic voltammetry measurements related to redox‐active nanofibers. These observations are expected to contribute to the advancements in application development of the electrochemically active nanofiber mats.