Characterization of the benzene-insoluble fraction of the hydrolyzate of phenyltrimethoxysilanes in the presence of benzyltrimethylammonium hydroxide

The insoluble fraction obtained from the hydrolysis and condensation of (4-dimethylamino-, 2-methyl-, and nonsubstituted)phenyltrimethoxysilanes in the presence of benzyltrimethylammonium hydroxide in benzene was characterized. IR, ¹H NMR, and ²⁹Si NMR suggested that the insoluble fraction was composed of RSi(O )₃, that is, a T³ structure. X-ray diffraction indicated the presence of a long-range ordered structure composed of a mixture of crystals. Raman spectroscopy strongly suggested a cage structure by the presence of a ring-opening vibration assignable to a cubic structure at 475–482 cm⁻¹. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4587–4597, 2004     

Formation of organotinnitrogen bonds : VI. The intermolecular association of 2-(tri-n-butylstannyl)-tetrazoles in solution

The intermolecular association of 2-(tri-n-butylstannyl)tetrazoles in benzene solution has been evaluated by the measurement of the apparent molecular weight. The degree of the association is highly dependent on the steric effect of the 5-substituent of the tetrazoles. Low temperature NMR spectra of CDCl₃ solutions of 2-(tri-n-butylstannyl)-5-phenyltetrazole and -5-(p-nitrophenyl)tetrazole displayed temperature- and concentration-dependencies. As the temperature decreases, the benzene and tetrazole rings become less coplanar. This may be attributed to the closer polymeric association of the 1-nitrogen to tin at low temperature. The intermolecular associated form of 2-(tri-n-butylstannyl)tetrazoles in less polar solvents such as benzene and chloroform is confirmed as a 1,3-structure (A).     

Ion heating by lower hybrid waves

An ion heating by excited lower hybrid waves has been observed in a coaxial type double plasma device. The lower hybrid resonance heating is examined on the two components of the kinetic energy perpendicular and parallel to the magnetic field.     

Diorganostannylenes : III. Formation of dimethylstannylene from 1,1-dimethyl-2,3,4,5-tetraphenyl-1-stannacyclopentadiene and acetylenes

Dimethylstannylene, (CH₃)₂Sn:, was formed transiently in the reaction of 1,1-dimethyl-2,3,4,5-tetraphenyl-1-stannacyclopentadiene (stannole) with dimethyl acetylenedicarboxylate or phenylacetylene. When this reaction was carried out in the presence of n-butyl bromide, dimethylstannylene inserted into the CBr bond of n-butyl bromide to give n-butyldimethyltin bromide in 12% yield, but most of the dimethylstannylene was captured by dimethyl acetylenedicarboxylate to give a complex. The complex was also produced in the photolytic reaction of the dimethyltin polymer, [(CH₃)₂Sn]_m, with dimethyl acetylenedicarboxylate. With phenylacetylene, dimethylstannylene did not give a similar complex, but polymerized to give the dimethyltin polymer.     

Garrett's pullback formula for vector valued Siegel modular forms

Let be the Siegel Eisenstein series of degree n and weight k. Garrett showed a formula of on Hp×Hq, where Hn is the Siegel upper half space of degree n. This formula was useful for investigating the Fourier coefficients of the Klingen Eisenstein series and the algebraicity of the space of Siegel modular forms and of special values of the standard L-functions. We would like to generalize this formula in the case of vector valued Siegel modular forms. In this paper, using a differential operator D by Ibukiyama which sends a scalar valued Siegel modular form to the tensor product of two vector valued Siegel modular forms, under a certain condition, we give a formula of and investigate the Fourier coefficients of the Klingen Eisenstein series.     

Preparation of monodispersed Pd nanoparticles by laser ablation at air–suspension interface

Strontium titanate (SrTiO₃) has attracted a lot of attention because of its possible applications in new microelectronic devices. It is a material with a high dielectric constant, low leakage current, and some of its properties can be changed by adding or modifying the concentration of a dopant, which can be used for a wide range of functional purposes, from simple capacitors to complicated microwave devices. Therefore, in this work, we report the development of a new route to synthesize SrTiO₃ nanoparticles based on the solvothermal method by employing two precursor solutions: strontium chloride and titanium(IV) butoxide. Our route allows the production of cubic SrTiO₃ nanoparticles with a narrow size distribution. The particle sizes range between 8 and 24 nm, forming agglomerates of SrTiO₃ in the range of 128–229 nm. It was demonstrated that the Ti/Sr molar ratio employed into the precursor solution has an important effect onto the chemical composition of the resulting SrTiO₃ nanoparticles: when using Ti/Sr < 1, the formation and incorporation of the SrCO₃ compound into the nanoparticles was observed while with Ti/Sr ≥ 1 nanoparticles are free of contaminants. The as-prepared nanoparticles were characterized by energy-dispersive X-ray spectroscopy, X-ray diffraction, transmission electron microscopy, high-resolution TEM, selected area electron diffraction, scanning electron microscopy, and dynamic light scattering.