Yoshiaki Inaki

Synthetic nucleic acid analogs preparation and interaction

In order to prepare simply designed nucleic acid models with high functionality, a series of polymeric compounds containing purine and pyrimidine bases as pendant, functional side groups were prepared successfully from their corresponding monomers by either polymerization or polycondensation techniques. As for the functionality of the polymers prepared, specific base-base interactions were studied in detail by measuring UV, NMR and emission spectroscopies. The specific interaction study was particularly made on poly-L-Lysine derivatives having nucleic acid bases in relation to their molecular weight, their conformation in solutions and other properties. From photodimerization study on the model compounds containing thymine bases, intramolecular features of the reaction were elucidated. Owing to the specific properties of the polymers, the studies will find a number of application possibilities, including separation techniques and polymeric drug chemistry. Graft copolymers of nucleic acid bases on polyethyleneimine were also concerned.

Vinyl Polymerization by Metal Complexes. XXXI. Initiation by Chitosan-Copper(II) Complex

Abstract The polymerization of methyl methacrylate and acrylonitrile can be initiated by the chitosan-copper(II) complex and its monomeric form, glucosamine-copper(II) complex, in the presence of carbon tetrachloride. The chitosan complex system was found to be more active for initiating the polymerization of methyl methacrylate than acrylonitrile at neutral pH. On the other hand, the glucosamine complex system showed no activity at neutral pH region, but had high activity at higher pH, because of the reducing endgroup of the glucosamine. Formation of the copper(II) complexes was studied by pH titration and visible spectroscopy. The relationship between complex formation and the activity for initiating the polymerization is discussed.

Syntheses and Photochemical Reactions of Bis-Thymine Derivatives

Bis-thymine derivatives were synthesized and their photochemical reactions in solution and in the film state upon irradiation of UV light above 270 nm were studied. The irradiation of these compounds caused the intramolecular and/or intermolecular photodimerization of thymine bases, leading to the photocyclization or photopolymerization of them. The probability of these reactions depended on the conformation of the thymine bases in the ground state, length and rigidity of the linking compound, and the reaction conditions in solution or in the film state.

Crystallization of poly(ethylene imine) amorphous sample in water vapor atmosphere

Infrared spectral measurement was carried out to find the crystallization of the amorphous poly(ethylene imine) (PEI) sample into the hydrates by absorbing water molecules. When PEI sample was melted and cooled to room temperature in dry state, it was found to crystallize into the anhydrate consisting of doubly stranded helices. But when the sample was melted and subjected to the humid atmosphere at the same temperature, the formation of hydrates was found to occur. The hydrates were considered to have higher melting points than the anhydrate, in other words, they were more stable than the anhydrate in higher temperature region.

Nucleic Acid Analogs: Their Specific Interaction and Applicability

A variety of poly(amino acid) and poly (ethyleneimine) derivatives, having pendant nucleic acid bases and nucleosides, were prepared using polymer modification reactions. The conformation of the polymers was studied by CD and ORD measurements. Further study about the polymer complex formation between complementary polymers revealed that the complexes were formed by specific base pairing between pendant bases, retaining their helical conformation in the case of poly (amino acid) type polymers.

Functional monomers and polymers. CLXXVII: Synthesis and interaction studies of water soluble nucleic acid analogs: polyethyleneimine derivatives containing uracil and 5-fluorouracil

Nucleic acid analogs were prepared by grafting uracil and 5-fluorouracil de rivatives containing a hydroxy group onto linear polyethyleneimine. The polymers contained about 90 unit% of the nucleic acid bases, and were freely soluble in water at neutral pH value. They were found to form polymer com plexes with polynucleotide by specific base-base interaction in aqueous solu tion.

Synthesis and Properties of Hyaluronic Acid Conjugated Nucleic Acid Analogs—1: Synthesis of Deacetylhyaluronan and Introduction of Nucleic Acid Bases

The conjugation of nucleic acid base with hyaluronan was achieved by using the activated ester of pentachlorophenyl trichloroacetate. The conditions of de-N-acetylation of sodium hyaluronic acid were studied. In low concentrations of NaOH, the degree of deacetylation was 26%, while in 7.4N NaOH, the degree of deacetylation was 76% and the viscosity was 1.12 dL/g. Thymine and 5-fluorouracil bases were quantitatively conjugated to deacetylhyaluronan in 65% and 51%, respectively. The interaction of thymine hyaluronan conjugate with the complementary base of polyadenylate showed a small hypochromicity.

Vinyl Polymerization by Metal Complexes. XXXII. Formation of Glycolchitosan-Copper(II) Complex and the Initiation of Vinyl Polymerization by Using the Complex

Abstract The formation of the water-soluble glycolchitosan-copper (II) complex was studied by ultraviolet and visible spectroscopy and by viscosity measurement. The structure of the polymer complex in question was found to change with pH value of the system. The glycolchitosan-copper (II) complex was active as a free-radical initiator for the polymerization of methyl methacrylate and acrylonitrile in the presence of carbon tetra- chloride. The maximum conversion was observed at neutral pH, and was influenced by the presence of neutral salts. Relation- ship between the activity of the polymer complex for initiating the polymerization and its structure was discussed.

Vinyl Polymerization by Metal Complexes. VII

Abstract The photopolymerization of vinyl monomers by metal salt-saccharide system was investigated in various solvents. The rate of polymerization in the presence of a iron(III) salt in aqueous media was remarkably accelerated by the addition of saccharides. The acceleration caused by a series of saccharides was found to be in the following order: glucose > fructose > lactose maltose. α-Methyl-d-glucoside and sucrose exhibited very little effect. The overall activation energy for the photopolymerization of acrylonitrile in the presence of glucose was found to be 2.7 kcal/mole, about half of the value obtained in the absence of glucose.

Photodimerization of Thymine-Containing Polymers: Applicability to Reversible Photoresists

Abstract The intramolecular photodimerization of thymine bases present on the side chain of a variety of synthetic oligomers and polymers was studied in detail in various organic solvents, and particularly in the case of thymine-containing polylysines, over a wide range of pH. Effects of solvents, presence of the complementary base, and spacers on the photoreaction were examined, and the conformational changes of the polymers were discussed in relation to their functionalities. Intermolecular photodimerization was further studied, and its applicability to photoresists was shown.