Kyo Abe

Synthesis of 1,3-bis(diarylamino)benzenes as model precursors for one-dimensional organic ferromagnetic metals; characterization of the dications by cyclic voltammetry and electron spin transient nutation spectroscopy

Abstract A series of 1,3-bis(diarylamino)benzenes as model precursors for 1D organic ferromagnetic metals were synthesized. Cyclic voltammetric measurements showed that the corresponding monoand dication radicals with protecting groups were stable enough even at ambient temperature. A triplet state for the dication was unequivocally identified by a novel electron spin transient nutation spectroscopy.

Electrolytic desulphinylation of 1-methylsulphinyl-1-methylthio-2-phenylethene in acetonitrile

Abstract The electrolytic reduction of (E)-1-methylsulphinyl-1-methylthio-2-phenylethene ( 1 ) in acetonitrile involves selective cleavage of one carbon-sulphur bond, resulting in formation of (E)-1-methylthio-2-phenylethene ( 2 ) in good yields, but not the (Z)-isomer, in the presence of excess phenol and benzoic acid, respectively, as proton donor and at all the following electrodes; mercury, platinum, lead, and glassy carbon. Polarographic studies of 1 and its related compounds such as 1,1-dimethylthio-2-phenylethene ( 3 ), (E)-1-methylsulphinyl-2-phenylethene ( 4 ), and 2 has revealed that the electrolytic reduction of 1 to 2 proceeds via neither 3 nor 4 , but via elimination of the methylsulphinyl group.

Electrosynthesis of sulfur-containing organic compounds from allene derivatives using a sacrificial mixed sulfur/graphite electrode

Abstract Electrosynthesis of sulfur-containing organic compounds from cumulene derivatives was studied using a sacrificial sulfur-graphite electrode. 1,1-Di- p -chlorophenyl-4,4-diphenylbuta-1,2,3-triene ( 1a ), 1,1-di- p -chlorophenyl-4,4-di- p -methylphenylbuta-1,2,3-triene ( 1b ), 1,1,4,4-tetraphenylbuta-1,2,3-triene ( 1c ) and 1,1-di- p -methoxyphenyl-4,4-diphenylbuta-1,2,3-triene ( 1d ) were used as cumulenes. With 1a , 1b and 1c , 7-membered ring compounds with five sulfur atoms such as pentathiepins 2a , 2b and 2c were produced as the major products accompanied with dimeric compounds 3a , 3b and 3c which had a 1,2,5,6-tetrathiocin skeleton in minor amounts, respectively. However, 1d , which is the most difficult to be reduced among the cumulenes studied, did not give sulfur-containing organic compounds. Yields of 2a , 2b and 2c decreased a little by the addition of a proton donor such as benzoic acid. Main products 2 will be initiated by a Michael addition of the polysulfide anion(s) (S 8 2− and/or S 6 2− ) produced by electroreduction of elemental sulfur. By-products 3 will be probably produced by further reaction of 2 with the polysulfide anion(s).

Cathodic elimination of 1-methylthio-1-p-tolylsulphonyl-2-arylethenes in non-aqueous media

Abstract The electrolytic reduction of 1-methylthio- p -tolylsulphonyl-2-arylethenes (1) in acetonitrile and N , N -dimethylformamide involves selective cleavage of a carbon—sulphur bond, resulting in formation of (E)-1-methylthio-2-arylethenes (2) in moderate yields with the consumption of about 2 electrons per mol, in the presence of efficient proton donors such as phenol and benzoic acid and at all the following electrodes; mercury, platinum, lead and glassy carbon. In the absence of proton donors, as was expected, the yield of 2 is very low and the hydrodimerization of 1 takes place.

Models for positive charge fluctuation vs. spin polarization in organic systems; synthesis and cyclic voltammetry of 2D and 1D hyperbranched π -aryl-based amines

Abstract A series of substituted N,N,N′,N′,N″,N″hexaphenyl-1,3,5-triaminobenzene(TAB) and N,N,N′,N′tetraphenyl-1,3,5 triaminobenzene(DAB) were synthesized as models for positive charged fluctuation vs. spin polarization in organic systems. CV measurements at low temperature showed that the chemical stability-in-solution of mono and poly-cationic oxidation states of the various HPTABs and TPDABs derivatives depend on their molecular structures and substituents.

Synthesis by benzilic acid rearrangement of the 2-oxo-3-pyrroline dimeric alkaloid of Mercurialis leiocarpa

Abstract The 2-oxo-3-pyrroline dimer, 3,3′-bis(1,1′-dimethyl-2,2′-dioxo-4,4′-dimethoxy-5,5′-dihydroxy-5,5′-dimethoxycarbonyl-3-pyrroline), present in Mercurialis leiocarpa has been synthesized.

Spin Identification of Polyionic High-Spin Aryl-Based Heteroatomic Systems by 2D Electron Spin Transient Nutation (2D-ESTN) Spectroscopy

Abstract Molecular design, generation, and spin identification of polyionic high spins with heteroatomic π-conjugation are described. The molecular design was based upon the π-topological pseudo-degeneracy of HOMOs for high-spin polycations and LUMOs for high-spin polyanions. The pseudo-degeneracy originates in heteroatomic perturbation and high spin preference in their ground state is driven by meta- or 1,3,5-connectivity of heteroatomic sites giving rise to additive dynamic spin polarization. Polyionic high spins were generated by chemical oxidation or reduction in solution. Thus, the polyions were observed in a rigid glass solution containing reaction mixture. For such complex spin systems their reliable spin identification is essential and, therefore, we employed field-swept 2D electron spin transient nutation (2D-ESTN) spectroscopy. In this work, we have developed such a 2D-ESTN spectroscopy as deserves to enhance spectral resolution in complex spin mixture of non-oriented systems. An unequivocal a...

Spin alignment in high-spin carbenes of heteroatomic π-conjugation

Abstract 2,6-, 2,4-, And 3,5-pyridine-bis (phenylmethylene) (3,5-PY), in which heterocycle plays a ferromagnetic or antiferromagnetic linker between carbenic units, have been studied by random orientation ESR spectroscopy. The electronic structures of isomers are important for the understanding of spin alignment vs. topology of the heteroatomic π-electron networks. In 2,6-PY and 2,4-PY, the perturbing nitrogen atoms are in active positions, giving rise to a larger influence on their spin structure than in 3,5-PY. A simple application of molecular Hunds rule is invalidated

Molecular design for polyionic organic ferromagnets and syntheses of model oligomers; Exploitation of topological superdegeneracy of π-BCO's and π-ABCO's, and high spin characterization by FT pulsed ESR/ESTN spectroscopy as a novel experimental technique

Abstract The conceptual proposals of organic magnetism/molecule-based magnetism in terms of non-charged open-shell units were made as early as 1960s. One of the highlighted advances has been that the use of topological-symmetry requirement in the electron network of it-conjugated homoatomic neutral hydrocarbon systems gives rise to the unlimited number of the degeneracy in non-bonding molecular orbitals (coined as topological degeneracy). This paper deals with the π-topological version of an approach to purely organic polyionic polymer ferromagnets, emphasizing that molecular design exploits the topological pseudo superdegeneracy of π-bonding and -antibonding crystal orbitals (π-BCOs and π-ABCOs; π-bands) appearing close to zero energy in heteroatomic π-conjugated organic systems, for pofycationic and poryanionic organic polymer ferromagnets, respectively. The appearance of the BCOs and ABCOs close to zero energy as well as their pseudo degeneracy is due to heteroperturbation. Their superdegeneracy arises from the topological nature of the electron network of π-conjugation. Oxidation and reduction states of polymers designed according to the topological approach are expected to undergo dynamic spin polarization, leading to high-spin ground states for porycationic and poryanionic model porymers, respectively. One-dimensional and two-dimensional star-burst model oligomers with heteroatoms in π-conjugation were designed and synthesized Their electronic high-spin ground states have been identified by means of Electron Spin Transient Nutation (ESTN) spectroscopy based on FT pulsed ESR technique to which recently we have exerted ourselves in order to obtain technical advances in molecular spin science underlying the research field of molecule-based magnetism. Most of the poryionic high-spin species have been generated by wet processes, i.e., chemical reaction in solution. In this study, the poryketone-based poryanionic high-spin species have been generated also by a dry process, i.e., electron attachment via γ-irradiation in organic glasses.

Electronic States and Spin Characterization of Polyanionic High-Spin Molecules and Clusters Derived from 1,3-Dibenzoylbenzene Derivatives as Studied by ESR/Electron Spin Transient Nutation Spectroscopy

Abstract The systems under study were 1,3-dibenzoyl benzene (1), its methyl derivatives (2,3), and 2,6-dibenzoyl pyridine (4), all of which have topologically pseudogenerate π-LUMOs. The corresponding dianions are expected to form triplet ground states and the anionic molecular assemblages expected to form polyanionic high-spin clusters. The polyanionic molecules and clusters were generated by chemical reduction and investigated by cw/FT pulsed ESR spectroscopy. Alkali metal-bridged high-spin clusters were identified directly by FT pulsed ESR-based 2D Electron Spin Transient Nutation (2D-ESTN) spectroscopy. We found ground-state quintet, quartet, and triplet dimers originating in the oligoketone with pluri-electron doping. We determined all the zero-field splitting parameters, g-values, and the concentration ratio of the high-spin systems with the help of spectral simulation.