Toyonari Sugimoto

Synthesis and properties of ethanediylidene-2,2′-bis(1,3-dithiole)

Abstract A new type of electron donors in the charge-transfer complex formation, ethanediylidene-2,2′-bis(1,3-dithiole)′s, have been synthesized by the reaction of (1,3-dithiolidene)phosphoranes with 2-formylmethylene-1,3-dithioles and their properties have been discussed.

Synthesis and properties of 1,3-dithiole-[3]- and [4]-dendralenes, acyclic systems of the corresponding [3]- and [4]-radialenes

Abstract 1,3-Dithiole-[3]- and [4]-dendralenes ( 2 and 3 ) have successfully been synthesized by using Vilsmeyer reactions on 2,2′-(ethanediylidene)bis(1,3-dithiole) ( 5 ) and 2 and the following Wittig reaction. Their electrochemical properties are discussed in comparison with those of 5 and 1,3-dithiole[4]radialene ( 4 ). Furthermore, conversion of 2 and 3 to 1,3-dithiole-[3]radialene and 4 , respectively, was attempted by using zero-valent nickel complexes.

Stereoselective oxidation of aromatic sulfides and sulfoxides in the binding domain of bovine serum albumin

Abstract The oxidation of aromatic sulfides with achiral oxidizing agents, e.g., sodium metaperiodate (NaIO 4 ) and hydrogen peroxide (H 2 O 2 ) in the binding domain of bovine serum albumin (BSA), furnished a strong asymmetric bias (max 81%) of the product sulfoxides in fairly high chemical yields. The kinetic resolution of racemic aromatic sulfoxides was also carried out in the chiral binding domain, and the remaining unchanged sulfoxides showed optical purities ranging over 1–33% at ca. 50% completion of oxidation. The combination of the two stereoselective oxidations above mentioned produced several optically active sulfoxides of >90% optical purity in ca. 50% chemical yield. The present method constitutes a successful biomimetic approach to achieving stereoselectivities as high as obtained by sulfur-oxidizing microorganisms.

New Charge-Transfer Complex-Based Organic Ferromagnets: Pyridinium-Substitued Imidazolin-1-Oxyl/ Tetrafluorotetracyanoquinodimethanide or Hexacyanobutadienide Salts

Abstract The charge-transfer (CT) complexes of a series of 4,4,5,5-tetramethylimidazolin-1-oxyls substituted with 4-(N-alkylpyridinium) groups at the 2-position with two radical anions, tetrafluorotetracyanoquinodimethanide (TCNQF4–) and hexacyanobutadienide (HCBD–) were prepared and their magnetic properties were investigated in the temperature range of 5 to 300 K. Ferromagnetic interaction was observed for the three CT complexes. Furthermore, the magnetic measurement at lower temperatures than 5 K showed that these CT complexes exhibited a ferromagnetic phase transition between 0.4 and 0.55 K. Consequently, the present CT complexes make a group of another type of organic ferromagnets without any magnetic metal elements.

A hydrolytic enzymelike behavior or bovine serum albumin in hydrolysis of p-nitrophenyl esters

Abstract The investigation of hydrolysis of p-nitrophenyl acetate (NPA) catalyzed by bovine serum albumin (BSA) proved that the initial rate in the steady state folows a Michaelis-Menten equation. In the use of D- and L-p-nitrophenyl α-methoxyphenlacetates (D- and L-NPMAs) as an enantiomeric ester, the L-enantiomer is hydrolyzed about three times faster than the D-enantiomer, mainly due to stronger binding of the former enantiomer by BSA.

A novel synthesis of half-protected 1,3-dicarbonyl compounds

Abstract It has been found that the reaction of enol silyl ethers with 2-ethoxy-1,3-dithiolane proceeds smoothly in the presence of zinc chloride catalyst to afford half-protected 1,3-dicarbony1 compounds in moderately good yields.

New donors for organic metals

Abstract Six kinds of new donors ( 1 – 6 ), in which formally two or three sp 2 carbons are inserted between two 1,3-dichalcogenoles or four 1,3-dithiol-2-ylidene moieties are combined into cyclobutaneylidene framework, were synthesized. From comparison of the first oxidation potentials between the new donors and TTF, it was shown that the formers have superior donating ability to the latter. The new donors formed charge transfer salts with TCNQ ot TCNQF 4 , and the room temperature conductivities of the salts on compressed pellets were in the range of 0.03 – 0.8 S/cm. In particular, the 1 - TCNQ saltt was obtained as a single crystal, and the conductivity increased with decreasing temperature in the range of 300 (16 S/cm) and 200 K (23 S/cm).

Reaction of thiopyrylium ion with active methylene compounds

Abstract The reaction of 2,4,6-triphenylthiopyrylium ion with several active methylene compounds in the presence of base has been found to yield 2,4,6-triphenylbenzene derivatives. In the case of the reaction of 2,4,6-triphenylthiopyrylium fluoroborate with nitromethane, an alkali treatment gave 2,4,6-triphenylnitrobenzene, and an acid treatment afforded 2,4,6-triphenylbenzene, respectively. From these results, the reaction behaviour of the thiopyrylium ion has been discussed.

New π-electron donors: Ethanediylidene-2,2′-bis(1,3-diselenole) and ethanediylidene-2-(1,3-dithiole)-2′-(1,3-diselenole)

Abstract This communication describes synthesis and electrochemical properties of new type of π-donors containing 1,3-diselenole ring, ethanediylidene-2,2′-bis(1,3-diselenole)(1a) and ethanediylidene-2-(1,3-dithiole)-2′-(1,3-diselenole)(2a). The conductivities of the charge-transfer complexes of these donors with tetracyanoquinodimethane (TCNQ) are also demonstrated.

Weak ferromagnetism below 12 K in a lithium tetrafluorotetracyanoquinodimethanide salt

Abstract The spin interaction between TCNQF 4 −. molecules in the Li + , Na + , K + , Rb + , Cs + and NMe 4 + salts was investigated in the temperature range of 2 to 300 K. The other salts than Li + ·TCNQF 4 −. exhibited almost temperature-independent small susceptibilities, indicating disappearance of the free radical moments. On the other hand, the susceptibility of the Li + salt obeyed a Curie-Weiss law above 50 K with a Curie constant of 0.36(1) emu K mol −1 and an asymptotic Curie temperature of −30(2) K. A sudden enhancement of the susceptibility was observed at 12 K. These results suggest an antiferromagnetic ordering of the radical anions accompanied with spin cantings (weak ferromagnetism) in the Li + salt below 12 K.