Two types of silylmethylated C₆₀ were prepared by addition of Grignard reagents, ClMgCH₂SiY₃(Y = alkyl, aryl, alkoxy), to C60. In THF, C₆₀ (H) (CH₂SiY₃) was formed as a major product, whereas Co (CH₂SiY₃)₂ was selectively produced in toluene. Structures of these compounds were characterized by spectroscopy. Semi-empirical molecular orbital calculations revealed the electronic structures. Redox properties were studied by cyclic voltammetry. Derivatives derived from ClMgCH₂Si( CH₃)₂ [ OCH (CH₃)₂] were converted to the corresponding chlorosilanes by way of alkoxy exchange of the isoprop oxy group to chlorine atoms with AlCl₃ and other chlorinating reagents. The chlorosilanes readily reacted with alcohols in the presence of 2, 6-lutidine with the aid of AgOSO₂CF₃ to form C₆₀ (H) CH₂Si (CH₃) ₂(OR) and C₆₀[ CH₂Si ( CH₃)₂ (OR)] ₂, where R=various alkyl and aryl groups. The chlorosilanes, C₆₀( H )CH₂Si (CH₃)₂ ( Cl), and polyalkoxy silanes, C₆₀( H) CH₂Si(CH₃)(OR) _3-n, and C₆₀[ CH₂Si (CH₃)n (OR) _3-n]₂, where n= 0 or 1, were useful reagents for surface modification of silica. The modified silica was useful as stationary phases of High Performance Liquid Chromatography or as a heterogeneous photosensitizer. Thermal analysis of a derivative having a cyclic siloxane structure led to successful preparation of its vacuum deposited thin films.

View full abstract

In order to make clear the formation of 2-aminopyridinium acetate complex in the 2-aminopyridine acetic acid system in the ground state, the ab initio molecular orbital calculation at the 6-31G level with a geometry-optimization was carried out for the 2-aminopyridine formic acid system used as a model system for the 2-aminopyridineacetic acid system, and the IR spectrum of the 2-aminopyridineacetic acid system was measured to ascertain the formation of the 2-aminopyridinium acetate complex. From these results the following conclusions were drawn: (1) In the ground state the 2-a minopyridineformic acid complex (amino complex) is most stable, and its stabilization energy is 75.69 kJ mol^-1. (2) The next stable complex is the 2-aminopyridinium formate complex (cation complex), and its stabilization energy is 67.63 kJ mo1^-1. Its stabilization energy is comparable in magnitude to the corresponding one of the former complex model. (3) The calculated potential barrier height of the proton-transfer process from the amino complex to the cation complex is about 13 kJ mol^-1 and its potential energy curve has a stable potential minimum which corresponds to the energy of cation complex. These results suggest that the proton-transfer may occur easily. (4) The third stable complex is the 2 (1H) -pyridinimineformic acid complex and its stabilization energy is 28.67 kJ mol^-1. The calculated potential energy surface suggests that the amino-imino tautomerization may proceed through the cation complex from the amino complex. (5) From similarity of formic acid to acetic acid in chemical property the above conclusion may be applicable to the 2-aminopyridine acetic acid system. (6) Experimentally, the characteristic bands ascribed to the amino and cation complexes were observed in the region from 4000to 1800 cm^-1 of the IR spectrum of the 2-aminopyridine acetic acid system. Especially, the bands at 3000 and 2500 cm-1 were attributed to the 2-aminopyridineacetic acid complex and the bands at 3200and 1925 cm to the 2-amino pyridinium acetate complex. These band assignments were done by referring to the results of normal coordinate calculation of the amino and cation complexes and IR spectra of the 2-methylaminopyridineand 2-amino-3-nitropyridine acetic acid systems.

View full abstract

The growth of ruby (Al₂O₃: Cr) crystals from PbF₂-B₂O₃ flux is reported. The crystal growth was conducted by heating a mixture of solute and flux at 1100°C for 10 h, followed by cooling to 500°C at a rate of 5, 10, 20 or 40°C h-1. Red and transparent ruby crystals were obtained. A combination of slow cooling with evaporation of the flux produced crystals of ruby. The simple PbF2 flux gave ruby crystals of up to 12 mm x 9 mm x 1 mm in size. The crystal sizes decreased with increasing rate of cooling. The evaporation loss and crystal size decreased with increasing amount of B₂O₃ added to PbF₂. The PbF₂-B₂O₃ flux produced a lot of small ruby crystals. Inclusions were rarely found in the ruby crystals. The form of the ruby crystals was a hexagonal thin plate bounded by c{0001}, r{1011} and d{0112} faces. On the basis of microscopic observation, the central parts of c faces were slightly swollen. The growth hillocks were observed on the c faces of crystals. The step heights of the hillocks were in the region of 0.2-15 pm. The chromium was incorporated preferentially in the center parts of crystals. The refractive index of transparent ruby crystals was 1.73 ± 0.01.

View full abstract

An improved standard addition potentiometry for a sample of waterorganic solvent mixtures, in which the adjustments of both the ionic strength and the solvent composition are not required, is proposed.
After the sample of the waterorganic solvent mixture of volume V, in which an ion-selective electrode and a reference electrode are immersed, is titrated with the aqueous solution of the diluent and the electromotive forces (E¹) which correspond to volumes (vd) of the added diluent are measured (the final volume of the added diluent is denoted with vdo) the same sample solution of another certain volume WO is added to the titrated sample. Subsequently this mixed sample is titrated again with the aqueous solution of the standard containing the analyte ion of a known concentration (cs) and having the same ionic strength as that of the diluent, and the electromotive forces (E²) which correspond to volumes (vs) of the added standard are measured.

View full abstract

The reaction between aryl Grignard reagents and aryl halides in the presence of non-ligated nickel (II) chloride (NiCl₂) affords the cross-coupling products in high yields. It is found that NiCl₂ effectively catalyzes the coupling of aryl Grignard reagents with bromoarenes, but it has a low catalytic activity towards chloroarenes. The high halogen-selectivity which was not found in the reactions using phosphine-ligated nickel complexes is a unique feature of the NiCl₂-catalysis for the cross-coupling reaction. By the halogen-selectivie NiCl₂-catalyzed cross-coupling, we synthesized unsymmetrical terphenyls, which are important materials for a heat-stable polymer. On the other hand, for the crosscoupling reactions of heteroaromatics, NiCl₂ was not act as an active catalyst, but the cross-coupling reaction of thienylmagnesium halides with chloroiodobenzene proceeded selectively to give (chlorophenyl)thiophenes.

View full abstract

Enantioselective hydrolysis of amino acid esters by L-histidine derivatives in the molecular assemblies composed of single- and double-chain surfactants was investigated.
The remarkably high enantioselectivity (k^L_{a, obsd}/ k^D_{a, obsd}=1000) was attained for the hydrolysis of longchained substrates (N-dodecanoyl-D (L)-phenylalanine p-nitrophenyl ester; C₁₂-D( L ) - Phe-PNP) catalyzed by the active tripeptide (N- (benzyloxycarbony1)-L-phenylalanyl-L-histidyl-L-leucine; Z-PheHisLeu) in the coaggregate systems composed of 41 mol% hexadecyltrimethylammonium bromide (CTAB) and 59 mol% ditetradecyldimethylammonium bromide (2C₁₄Br) at the specific ionic strength (μ=0.02).
Furthermore, the computer modeling (MOPAC calculation)study suggests that a favorable molecular recognition between the substrate and the catalyst through the effective hydrophobic interactions and hydrogen bonds should be very important for the enhancement of enantioselectivity.

View full abstract

As a homology of the diamine, which has been demonstrated as a hole transportating material in organic electroluminescent diode by C. W. Tang et al., 9, 9-bis{p-[N, N-bis (p-substituted phenyl)amino]phenyl}fluorenes (abbreviated as Flu-diamine) have been synthesized by means of a m odified Ullmann synthetic procedure. Their single thin film devices, [ _??_ ITO _??_ Flu-diamine _??_ Al _??_ ], have been fabricated to examine their current-voltage characteristics. The order of their threshold voltage has been found to be parallel to that of the positive inductive effect of the substituents on p-substituted phenyl group. This order is also parallel to that of redox potentials of Flu-diamines in cyclic voltammetry.

View full abstract

Polyetherurethaneureas (PEUUs) including methyl- or fluoro substituted biphenyldiyls (BP, nMBP, nFBP) in main chain were obtained from a typical two step addition polymerization of polytetrahydrofuran #1000 (PTHF) to 4, 4'-methylene bis (phenyl isocyanate) (MPI) in the presence of the substituted biphenyldiols, using ethylenediamine (EDA) as a chain extension reagent. Biphenyldiols used were 4, 4'-biphenyldiol (BP), 3, 3'-dimethy1-4, 4'-biphenyldiol (2MBP), 3, 3', 5, 5'-tetramethy1-4, 4'-biphen yldiol (4MBP), 4, 4'-biphenyldiol (2FBP), 3, 3', 5, 5'-tetrafluoro-4, 4'-biphenyldiol (4FBP), and 2, 2', 3, 3', 5, 5', 6, 6'-octafluoro-4, 4'-biphenyldiol (8FBP). Polyaddtion with a molar ratio of 0.5: 0.5: 2: 1 for the biphenyldiol: PTHF: MPI: EDA in the mixed solvent of DMSO and IBMK (1:1) gave the PEUU s such as PEUU-BP, PEUU-nMBP, PEUU-nFBP. Parent polyetherurethaneurea (PEUU) was also prepared with a molar ratio of 1: 2: 1 for PTHF: MPI: EDA. XPS spectra of the PEUUs indicated that the hydrophobic segments containing the substituted biphenyldiyl moieties are located on the surface of the PEUUs film in air. The measurements of contact angle to water confirmed that the introduction of methyl groups or fluorine atoms into biphenyl ring results in higher hydrophobicity of PEUUs film surface. The tensile modulus (E) showed the values of E= 109.1 MPa and E= 129.3 MPa for PEUU-4MBP and PEUU-4FBP, respectively. It was also found that PEUU-nMBP and PEUUnFBP, adsorb both bovine serum albumin and human serum y-globulin with a single layer. In cell culture test, the PEUUs films showed the adhesiveness of mouse fibroblast (L-929). Because of their mechanical and biocompatible properties, PEUU-nMBP and PEUU-nFBP are expected to be useful materials as an artificial blood vessel.

View full abstract

Effective adsorption of dilute nitrogen oxides (N0x) is one of the most important processes for purifying the polluted air, for i nstance in t unnels or on busy roads. Activated carbon fibers (ACF, Tab le 1) were examined on their usefulness as adsorbents for the removal of dilute NO, where NO is a main component of NOx.
Adsorption t ests were carried out at room temperature with an NO measuring apparatus in w hich a controlled potential electrolysis sensor was used (Figs.1 and 2). ACFs in an “as received” state i. e. without pretreatment were found to adsorb a considerable amount of N O at 5 p pm concentration dilut ed with air o r N2( Fig.4). T he test gas was t hen to b e dried with s ilica gel. O n t he other h and, the AC Fs preheated at 423 K for 24 h in air showed very low capacities of NO adsorption except for PAN-ACF, even though preheating adsorbent is a usual treatment and a matter of course.
Each of the 4 kinds of ACF showed its particular characteristics of NO adsorption (Fig.6, Tables 2and 3). P AN-ACF's NO adsorption capacity reached 0.071 mmolig. The ACF samples' weight reduced by 7-25% during NO adsorption tests, which corresponds presumably to the removal of ad sorbed water on t he ACFs (Fig.7). T here were limited scopes for h eating ACFs without damaging thei r NO adsorption capacity and for recovering it after NO desorption (Figs.8 and 9). When heated at 473 K, a PAN-ACF sample having fully a dsorbed NO evolved to a maximum NO concentration of 3 80 ppm and maximum NO2 o f 3.6 ppm in a very short time ( Fig.10).

View full abstract

Several diamine/acid salts were reacted with Nylon 6 in melt state to increase ammonium terminal groups in Nylon 6. Especially, 1, 6-diaminohexane/methanesulfonic acid (1: 2) salt was found to be the most effective for this terminal modification. When its molar ratio was 1.2 relative to the terminal carboxyl groups of Nylon 6, a significant amount of the ammonium-sulfonate groups were introduced without decreasing the solution viscosity of polymer. Various model reactions revealed that the diamine/acid salts can react with the terminal carboxyl groups or the inner amide groups of Nylon 6 to form the ammonium terminal groups. The same terminal modification was possible when the diamine salts were added to the polymerization system of ε-caprolactam. The reaction product of Nylon 6 and 1, 6-diaminohexane/methanesulfonic acid (1: 2) salt was melt-spun into a filament. Its dyeability to acidic dye was found to be very high even in a neutral bath because of increased ammonium terminal groups. This filament was then mixed with the formerly prepared s-triszine-terminated filaments and the original Nylon 6 filament, and the filament mixture was dyed in a mixed bath containing both acidic and basic dyes for cross dyeing. Each of the filaments was dyed with the corresponding dyes separately. This technique should be economically useful in dyeing industry and can be applied to the industrial production of new functional Nylon fiber or plastics. t Studies on Functionalizatio no f Polymers by Reactive Processing. Part 4.

View full abstract

On the synthesis of Ag2S-ZnS composite particles from the mixture of silver nitrate and zinc nitrate solution by homogeneous precipitation method using thioacetamide at 70°C, the effect of Ag⁺ concentration on the morphology of products was investigated.
The precipitates were spherical composite particles with narrow size distribution when Ag⁺ concentrations ≤4×10^-4 mol dm^-3. At Ag⁺ concentrations ≥4×10^-3 mol dm^-3, Ag₂S-ZnS composite particles became aggregated ones. The formation of spherical Ag₂S-ZnS composite particles occurred by the deposition of ZnS at the initial stage on the surface of Ag₂Snuclei which were formed by reaction between Ag⁺ ion and thioacetamide.

View full abstract

The reaction of N-acyl-o-aminophenol with 1-naphthoyl chloride in the presence of triethylamine gave N- (1-naphthoyl) -O-acyl derivative, while the same product was obtained from the reaction between N- (1-naphthoyl) -o-aminophenol and acyl chloride (RCOCl: R=CH₂OEt, CH₂OPh, or OCH₂Ph). The hydrazinolysis of the product revealed that the equilibrium between acyl-exchanged iso mers lies almost completely in favor of N-(1-naphthoyl)-O-acyl-o-aminophenol. This interesting result was explained on the basis of the strong electron-donating ability of an oxygen atom incorporated into the substituent Ras well as of the electrostatic model of exchanged isomer pair.

View full abstract