Ion-solvent interaction in nonaqueous solutions. II. Spin-lattice relaxation times of23Na and133Cs

The spin-lattice relaxation time (T ₁) of ²³ Na was measured in solutions of NaClO ₄ and (or) NaBr in formamide,N-methylformamide,N,N-dimethylformamide (DMF), MeCN, Me₂CO, tetrahydrofuran (THF), and dimethyl sulfoxide (DMSO), and ¹³³ Cs in a solution of CsCl in formamide. The values of (1/T ₁) ₀ obtained by extrapolation are discussed in terms of current theories of quadrupolar magnetic relaxation of ionic nuclei. A correlation was found between (1/T ₁) ₀ for ²³ Na and Gutmann's donor numbers.For Part I, see ref. 1.     

ΔE T N values of N-methylbenzenesulfonamide+acetone, +dimethyl sulfoxide,+ 1,2-dichloroethane and+2-propanol mixtures at 30 and 50°C

Binary mixtures of N-methylbenzenesulfonamide and some solvents (acetone, dimethyl sulfoxide, 1,2-dichloroethane and 2-propanol) were studied using an empirical solvatochromic parameter E _T ^N at temperatures of 30 and 50°C. Deviations of E _T ^N from ideal behavior were positive for each system at both temperatures studied. Results are discussed in terms of intermolecular interactions.     

Fine Patterning of Transparent, Conductive SnO2 Thin Films by UV-Irradiation

Finely patterned transparent, conductive SnO₂ thin films have been prepared. UV-light from a high-pressure mercury lamp was irradiated through a mask on the precursor films prepared from SnCl₂ with acetyl acetone in the ambient atmosphere, and this irradiation led to the change of solubility of the films in alkaline solution. Patterns with a width of about 3 to 50 m and thickness of about 0.1 m were formed with a pitch of about 2 to 20 m. The resistivity of the films heat-treated at 500°C after UV irradiation was about 1 × 10^–2 cm, which was almost the same resisitivity for the films heat-treated at 500°C without UV irradiation.     

MNDO study of reaction paths: Hydroboration of carbonyl systems

The hydroboration reactions of acetaldehyde and acetone have been investigated by the MNDO method. The reactions have been shown to be twostep reactions involving an intermediate adduct. This adduct subsequently undergoes hydrogen rearrangement. The hydroboration reactions of acetaldehyde and acetone have been compared with the corresponding reaction of formaldehyde. The charge transfer effects accompanying these reactions have also been discussed.     

A direct nitrogen-15 NMR study of cerium(III)-nitrate complexes in aqueous solvent mixtures

A study of the complex formation which occurs between cerium(III) and nitrate ions in aqueous solvent mixtures has been carried out by a direct, low-temperature, nitrogen-15 (¹⁵N) NMR technique. At temperatures in the range of –95 to –110°C, ligand exchange is slow enough to permit the observation of separate¹⁵N NMR signals for bulk nitrate, and this anion in the cerium(III) principal coordination shell. In water-acetone-Freon-12 mixtures, the spectra reveal the nitrato complexes do not form consecutively. Rather, signals are observed for Ce(NO₃)²⁺, Ce(NO₃) ₂ ¹⁺ , and only two other higher order complexes, even at very high NO ₃ ^– to Ce(III) mole ratios. Signal area evaluations were used to identify the possible higher order complexes. At comparable salt concentrations in aqueous-methanol mixtures, only Ce(NO₃)²⁺ and Ce(NO₃) ₂ ¹⁺ are formed, reflecting a decreased tendency for complexation in media of higher dielectric constant.     

A direct15N NMR study of erbium(III)-nitrate complexation in aqueous solvent mixtures

The extent of inner-shell ion-pair formation of Er³⁺ with nitrate ion in aqueous mixtures has been studied by nitrogen-15 (¹⁵N) NMR spectroscopy. At low temperature, exchange is slow enough to permit the direct observation of¹⁵N signals for nitrate ions in the Er³⁺ solvation shell and in bulk medium. In water-acetone mixtures,¹⁵N NMR signals for the mono-and bis complexes are observed at low nitrate to Er³⁺ mole ratios, but only the bis complex is evident at higher anion concentrations. No spectral evidence for the tris complex was seen at any nitrate concentration. In water-methanol-acetone mixtures, signals for the mono and bis complexes persist even at higher nitrate concentrations, indicating a reduced tendency to ion-pair with increasing dielectric constant. Preliminary¹⁵N NMR results are presented for the nitrate complexes of other paramagnetic lanthanide ions.     

Surface basicity of alkali metal-doped MgO by a new evaluation

A new parameter, ( v)^–1 is proposed for evaluating the surface basicity of alkali metal-doped MgO from a positive correlation with acetone/propene ratio in the decomposition of 2-propanol.     

ZnO-WO_3纳米材料催化化学发光法测定呼吸气中的丙酮

研究发现丙酮可在Zn O/WO3复合纳米材料表面产生强烈的化学发光现象。在考察波长、温度、流速等因素对该发光反应影响的基础上,设计了一种可测定糖尿病人呼吸气中丙酮的传感器。该传感器测定丙酮浓度的线性范围为0.025 9~5.18 mg/L,检出限为0.013 mg/L。呼吸气中其余气体如二氧化碳、氨气和水蒸气等不干扰测定。经连续60 h通过1.30 mg/L丙酮蒸气,26次测定结果的相对标准偏差(RSD)为3.6%,表明该传感器具有较好的使用寿命。     

Interval kinetic gravimetric sorption of acetone in random copolymers of poly(ethylene terephthalate) and poly(ethylene 2,6-naphthalate)

Interval sorption kinetics of acetone in solvent cast films of random poly(ethylene terephthalate)-co-(ethylene 2,6-naphthalate) (PET-co-PEN) are reported at 35°C and at acetone pressures ranging from 0 to 7.3 cm Hg. Polymer composition is varied systematically from 0% to 50% poly(ethylene 2,6-naphthalate). Equilibrium sorption is well described by the dual-mode sorption model. Interval sorption kinetics are described using a two-stage model that incorporates both Fickian diffusion and protracted polymer structural relaxation. The incorporation of low levels of PEN into PET significantly reduces the excess free volume associated with the glassy state and, for these interval acetone sorption experiments in ∼ 5 μm-thick films, decreases the fraction of acetone uptake controlled by penetrant-induced polymer structural relaxation. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2973–2984, 1999