Studies on imidazole derivatives as chelating agents-V Investigations of the applicabilities of the azoimidazoles as metallochromic indicators

Applicabilities of several azoimidazoles as metallochromic indicators were investigated in the light of the general equations expressing the colour change of the visual chelatometric titrations. By using the stability constants of the nickel(II), copper(II), zinc(II) and cadmium(II) chelates, the useful pH ranges, titration errors and sharpness of colour changes were predicted theoretically and the usefulness of these reagents as indicators was established experimentally. The Cu(II)-EDTA-indicator system was also examined experimentally. The OH-containing azoimidazoles could be applied to the direct titration of copper, nickel, zinc, cadmium, lead and bismuth and to the titration of calcium and cobalt in the presence of Cu(II)-EDTA. Attempts were made to construct diagrams for the estimation of titration errors and sharpness of colour changes.     

Thermal and Photochemical Isomerization of Tetraaryl Tetrakis(trifluoromethyl)

The isomerization of tetraaryl tetrakis(trifluoromethyl)[4]radialenes was studied. When type II (all-Z) isomers of 5,6,7,8-tetraaryl-5,6,7,8-tetrakis(trifluoromethyl)[4]radialenes were heated in tetralin at 170-200 degrees C, isomerization occurred to give mixtures of four [4]radialenes in a ratio of ca. I:II:III:IV = 1:10:5:1. However, when the isomeric mixtures were heated in the solid state at the same temperature, selective isomerization took place to give type II isomers in good selectivity (>91%). Upon irradiation with light, the type II isomers first isomerized to mixtures of the four [4]radialene isomers (I:II:III:IV = 2:2:48:48) and then rearranged to cyclobuta[b]naphthalenes via a 6pi-electrocyclic reaction followed by 1,3-hydrogen migration.     

Heat-resistant polymers with thianthrene analog units. II . Aromatic polyamides

A series of polyamides which contained thianthrene, phenoxatiin, and dibenzo-p-dioxin units was synthesized from tricyclic fused-ring diamines and aromatic diacid chlorides by solution polycondensations at a low temperature. The amorphous polyisophthalamides were highly soluble in polar organic solvents, whereas some of the polyterephthalamides with a fair degree of crystallinity were insoluble. The solubility of the series of polyamides increased in the order of the dibenzo-p-dioxin-containing polymers < phenoxatiin-containing polymers < thianthrene-containing polymers. The thermal stability increased in the reverse order and the dibenzo-p-dioxinpolyamides were more thermostable than the corresponding open-chain polymers with diphenyl ether linkages. The polyamides derived from 2,8-oriented tricyclic diamines showed somewhat lower glass transition temperatures than those from 2,7-oriented diamines.     

Cationic polymerization of 1-phenyl-4-ethyl-2,6,7-trioxabicyclo[2.2.2]octane

Cationic polymerization of bicyclo ortho ester, 1-phenyl-4-ethyl-2,6,7-trioxabicyclo[2.2.2]octane, was carried out with Lewis acids and cation sources to obtain the polyether containing ester group in the side chain. It was found that boron trifluoride etherate was the most active initiator in the Lewis acids. Magnesium perchlorate and triphenylcarbenium tetrafluoroborate, which have lower nucleophilic counter ions, initiated effectively the polymerization of bicyclo ortho ester.     

Syntheses of the stereoisomers of neolignans morinol C and D

Morinol C and morinol D are neolignans isolated from the Chinese medicinal herb Morina chinensis as racemates. (1R,2R)-Morinol C and (1S,2R)-morinol D were synthesized from (+)-(3R,4R)-4-(3,4-dimethoxyphenyl)-3-pivaloyloxymethyl-4-butanolide 4. On the other hand, (1S,2S)-morinol C and (1R,2S)-morinol D were synthesized from anti-aldol product 8.     

Characteristics of lithium iodide-containing poly(ethylene glycol) as a gas chromatographic stationary phase, and its application to analysis of amidic drugs

The characteristics of lithium iodide-containing poly(ethylene glycol) as a gas chromatographic stationary phase have been evaluated in terms of partial free energy of transfer (delta G t0) from poly(ethylene glycol) to the lithium iodide-poly(ethylene glycol) system for a variaty of amides (n-fatty acid amides, lactams, benzamides, anilides, nicotinamides, isonicotinamides, barbiturates, pyrazolones) and several amines. The changes in relative retention and resolution of two solute peaks caused by the addition of lithium iodide to poly)ethylene glycol) are correlated with the difference in their delta Gt0 values. The application to the specific separation of some amidic drugs is demonstrated.     

Expansion ratio dependence of lattice vibration of GaN using ab initio molecular dynamics calculations

Temperature dependence of Raman shift wavenumbers are important for the measurements of heat distribution of high-power GaN devices. In this study, calculated results of vibrational modes of ground state structure and some expanded structures of wurtzite type gallium nitride were presented using ab initio molecular dynamic (AIMD) simulations. Frequency analyses have been done for these calculated results and compared with the experimental results of temperature dependence of Raman spectra. Good agreement was achieved between the calculated and the experimental results quantitatively. AIMD would be a useful tool for the prediction of vibrating analysis for III-N systems.     

Neural uptake of catecholamines and their molecular structures: a histopharmacologic study.

Using ultrastructural and histofluorescence methods, we investigated the uptake mechanism of catecholamines by the nerve terminals in the cutaneous smooth muscles of stump-tailed macaques (Macaca arctoides). This in vivo approach ultilized the observed cytotoxic effects of 6-hydroxydopamine on these catecholamine-containing terminals and the protective effects of simultaneous treatment with catecholamines (dopamine, norepinephrine, and epinephrine), their 3-0-methylated derivatives (metanephrine and normetanephrine), and catechol acids (3,4-dihydroxymandelic acid and 2, 4, 5-trihydroxymandelic acid). Both catecholamines and 3-0-methylated derivatives protected these nerve terminals from destruction by 6-hydroxydopamine, but catechol acids did not. However, the 3-0-methylated derivatives were less effective than the catecholamines. The degree of protection afforded by these amines depended largely on their concentration. Only catecholamines intensified the electron density of the intravesicular mass or the fluorescence in the nerve terminals; therefore, 3-0-methylated derivatives may inhibit 6-hydroxydopamine uptake at axoplasmic membrane sites, but not inside the axon. These observations led to the discovery that these are two sites for the catecholamine uptake process. One site is the axoplasmic membrane. The terminals are protected by catecholamines and their 3-0-methylated derivatives from 6-hydroxydopamine uptake and thus destruction. The other site is the intraaxonal compartments. Here competitive binding between the vesicular protein and both 6-hydroxydopamine and the catecholamines plays a main role.     

Synthesis and radical polymerization of dissymmetric fumarates with alkoxyethyl and bulky siloxy groups

Novel dissymmetric fumarate monomers ( 1a – c ) having both an alkoxyethyl group such as 2‐methoxyethyl ( a ), 2‐(2‐methoxyethoxy)ethyl ( b ), and 2‐(2‐(2‐methoxyethoxy)ethoxy)ethyl ( c ) and a bulky 3‐[tris(trimethylsiloxy)silyl]propyl group were synthesized successfully, and their radical homopolymerizations and copolymerizations with styrene (St) were investigated. Monomer reactivities of the 1a – c in homopolymerizations were enhanced with an increase in the length of alkoxyethyl chains. The enhancement in the reactivity was explained with the suppression of the termination reaction, resulting from the increased steric hindrance induced by an increase in the size of alkoxyethyl chains. Copolymerizations of the 1a – c with St were carried out in bulk in the presence of AIBN at 60 °C, and their copolymerizations proceeded in a highly alternating tendency regardless of alkoxyethyl chain lengths. The Q, e values of the 1a – c were obtained as 0.48, +1.55 for the 1a , 0.66, +1.16 for the 1b , and 0.60, +1.16 for the 1c , respectively, from the terminal model reactivity ratios, and the 1a – c were found to be conjugative, electron‐accepting monomers. Membranes containing the 1a unit, prepared by the copolymerization of 1a with N‐vinylpyrrolidone (NVP) and terpolymerization of 1a , NVP, and 2‐hydroxyethyl methacrylate, have higher oxygen permeability than those containing no 1a unit, and also they have much better transparency compared with the membranes containing 3‐[tris(trimethylsilyloxy)silyl]propyl methacrylate unit. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 420–433, 2009