Nonclassical urea oligomers. IX. Photo-reducing nature of binuclear copper complexes of noncyclic pendant-type urea oligomers

The octameric oligomers of 1-(N-substituted-carbamoyl)-aziridine, i.e., N-ureanized-oligo-ethylenimines, form Cu(II) complexes. When the N-substituents are phenyl( 1, 3 ), methyl( 2 ), and p-tolyl( 4 ) groups, the main portions of the Cu( II )-complexes are binuclear. The binuclear oligomer–Cu( II ) complexes showed characteristic properties of photo-reduction of Cu( II ) species, giving rise to stable yellow Cu( I ) species. The ease of photo reduction strongly depends on the oligomer structures, especially on the nature of the pendant-urea groups, i.e., 4 > 1,3 > 2 . In the series of aromatic type urea-oligomers, highly stable photo-radicals were observed in ESR. By using an optically active oligomer ( 3 ) the molecular requirements for these characteristic properties were investigated with circular dichroism and cyclic voltammometry. And one of the plausible structures was deduced as the model of binuclear Cu( II ) sites surrounded by oligomeric environments.     

PREPARATION OF POLYMER DISPERSED LIQUID CRYSTALS USING PHOTOPOLYMERIZATION

2-Hydroxycthyl methacrylate (HEMA) and styrene copolymers are prepared by photopolymerization. The electro-optical behavior and microstructure of the polymer dispersed liquid crystal films are investigated by using He-Ne laser andscanning electron microscopy, respectively. With increasing E7 content in the copolymer, droplet size increased, thresholdvoltage decreased,     

Superoxide dismutase activity of a novel macromolecular manganese porphyrin

The discovery of a novel superoxide dismutase (SOD) mimic which demonstrates SOD activity, chemical stability in H₂O₂ solution and long half‐life in circulation is reported. The SOD mimic consists of a manganese porphyrin (MnP) with SOD activity and a polymer (poly (styrene‐co‐maleic anhydride); SMA) with biological characteristics. The SOD activity of SMA‐MnP at pH = 8.1 measured using the stopped‐flow kinetic analysis technique to monitor the decay of superoxide directly was 1.1 (± 0.1) × 10⁶ M‐1 sec‐1. It is postulated that the reduction by O₂^·− of the oxidized SMA‐Mn(III) is slow, while the oxidation of the reduced SMA‐Mn(II) by O₂^·− is very fast. The retention times of SMA‐MnP in the circulation of rabbits were determined. In vivo, SMA‐MnP that binds to the warfarin site on albumin showed an enhanced half‐life in the circulation. Additionally, in vitro SMA‐MnP indicated an excellent stability to H₂O₂. Copyright © 1999 John Wiley & Sons, Ltd.     

Novel synthesis of polyureas by ring-opening polyaddition-condensation reaction of 2-phenyl-1,3,4-oxadiazolin-5-one with diamines

A novel method for the synthesis of polyureas has been developed. This method involves ring-opening addition reaction of 2-phenyl-1,3,4-oxadiazolin-5-one with diamines, bis(4-aminophenyl) ether, 4,4′-methylenedianiline and m-xylylenediamine, followed by self-polycondensation of the resulting ring-opened adducts. Polymerizations in m-cresol at 150°C proceeded fast and were almost completed within 5 h. Polyureas were produced with reduced viscosities up to 0,38 dL · g⁻¹. A model compound study was performed to demonstrate the feasibility of the reaction for the formation of polyureas.     

Synthesis of a Series of Malonic Diester–Introduced Fullerene Derivatives

A facile preparation method for derivatization of fullerene through the Bingel reaction was introduced. A series of fullerene derivatives, to which malonic diester with different substituents were introduced, were systematically synthesized by Bingel reaction. Malonic diester could be added to fullerene at room temperature in the presence of iodine and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and various substituents such as phenyl, hexyl, thienyl, and pyrenyl were introduced into both sides of the malonic diester. As a result, 17 systematic variations were synthesized. The solubility parameters of the obtained fullerene derivatives calculated by the method reported by Fedors were in the range of 33 to 43 (J cm^?3)^1/2.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Conformation of ATP and ADP Molecules in Aqueous Solutions Determined by High-Energy X-ray Diffraction

High-energy X-ray diffraction measurements were carried out at 26 °C for aqueous 1.0, 2.0 and 2.05 mol% disodium adenosine 5′-triphosphate (ATP) and 2.0 and 2.05 mol% disodium adenosine 5′-diphosphate (ADP) solutions in order to obtain direct experimental information on the intramolecular conformations of ATP and ADP molecules in aqueous solutions. Observed interference terms were analyzed in terms of the intramolecular geometry of the ATP and ADP molecules. Dihedral angles between adenine and the ribose group (t ₁), ribose-ring and methylene group of ribose (t ₂), and the methylene group of ribose and triphosphate (or diphosphate) group (t ₃), were determined through the least-squares fitting procedure of the observed interference term.