Ce(Ⅳ)、Th(Ⅳ)与1,10-二氮杂菲-1-氧化物及乙酰丙酮的三元配合物

三元配合物的形成可明显改变单一配体配合物的性质,它们在分析、分离化学中已有广泛的研究和应用。由于Ce(Ⅳ)的强氧化性致使其三元配合物的合成较为困难。我们曾合成出三价稀土与1,10-二氮杂菲-1-氧化物(PhenNO)及乙酰丙酮(Hacac)的三元配合物。作为该工作的继续,本文研究了Ce(Ⅳ)、Th(Ⅳ)与PhenNO及Hacac三元配合物的合成与     

Complete settling of the multiplier conjecture for the case of n=3pr

In this paper we improve the character approach to the multiplier conjecture that we presented after 1992, and thus we have made considerable progress in the case of n = 3n₁. We prove that in the case of n = 3n₁ Second multiplier theorem remains true if the assumption “n₁ > λ” is replaced by “(n₁, λ) = 1”. Consequentially we prove that if we let D be a (v, k, λ)-difference set in an abelian group G, and n = 3p^r for some prime p, (p,v) = 1, then p is a numerical multiplier of D.     

Complete settling of the multiplier conjecture for the case of n=3pr

In this paper we improve the character approach to the multiplier conjecture that we presented after 1992, and thus we have made considerable progress in the case of n = 3n₁. We prove that in the case of n = 3n₁ Second multiplier theorem remains true if the assumption “n₁ > λ” is replaced by “(n₁, λ) = 1”. Consequentially we prove that if we let D be a (v, k, λ)-difference set in an abelian group G, and n = 3p^r for some prime p, (p,v) = 1, then p is a numerical multiplier of D.     

Study on Glucose Biofuel Cells Using an Electrochemical Noise Device

An electrochemical noise (ECN) device was utilized for the first time to study and characterize a glucose/O₂ membraneless biofuel cell (BFC) and a monopolar glucose BFC. In the glucose/O₂ membraneless BFC, ferrocene (Fc) and glucose oxidase (GOD) were immobilized on a multiwalled carbon nanotubes (MWCNTs)/Au electrode with a gelatin film at the anode; and laccase (Lac) and an electron mediator, 2,2′‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonate) diammonium salt (ABTS), were immobilized on a MWCNTs/Au electrode with polypyrrole at the cathode. This BFC was performed in a stirred acetate buffer solution (pH 5.0) containing 40 mmol/L glucose in air, with a maximum power density of 8 μW/cm², an open‐circuit cell voltage of 0.29 V, and a short‐circuit current density of 85 μA/cm², respectively. The cell current at the load of 100 kΩ retained 78.9% of the initial value after continuous discharging for 15 h in a stirred acetate buffer solution (pH 5.0) containing 40 mmol/L glucose in air. The performance decrease of the BFC resulted mainly from the leakage of the ABTS mediator immobilized at the cathode, as revealed by the two‐channel quartz crystal microbalance technique. In addition, a monopolar glucose BFC was performed with the same anode as that in the glucose/O₂ membraneless BFC in a stirred phosphate buffer solution (pH 7.0) containing 40 mmol/L glucose, and a carbon cathode in Nafion‐membrane‐isolated acidic KMnO₄, with a maximum power density of 115 μW/cm², an open‐circuit cell voltage of 1.24 V, and a short‐circuit current density of 202 μA/cm², respectively, which are superior to those of the glucose/O₂ membraneless BFC. A modification of the anode with MWCNTs for the monopolar glucose BFC increased the maximum power density by a factor of 1.8. The ECN device is highly recommended as a convenient, real‐time and sensitive technique for BFC studies.     

A Highly Selective and Sensitive Fluorescent Chemosensor for Aluminum Ions Based on Schiff Base

An efficient “off–on” type fluorescent chemosensor, (E)-N′-(4-(diethylamino)-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H ₂ L), based on Schiff base for the determination of Al³⁺ has been designed, synthesized, and evaluated. Upon treated with Al³⁺, the fluorescence of H ₂ L was enhanced 45-fold due to the chelation-enhanced fluorescence (CHEF) effect based on the formation of a 1:1 complex between the chemosensor and Al³⁺. Other metal ions, such as Na⁺, K⁺, Mg²⁺, Ca²⁺, Cu²⁺, Ga³⁺, Zn²⁺, Cr³⁺, Cd²⁺, Ag⁺, Fe³⁺, In³⁺, Mn²⁺, Pb²⁺, Co²⁺, and Ni²⁺ had little effect on the fluorescence. The results demonstrate that the chemosensor H ₂ L has stronger affinity with Al³⁺ than other metal ions. The detection limit of H ₂ L for sensing Al³⁺ is 3.60 × 10^?6 M in EtOH–H₂O (3:7, v/v) solution. And the recognizing behavior has been investigated both experimentally and computationally.     

Uranyl oxamate hydrates: hydrothermal synthesis,crystal structure,photophysical properties,and selective crystallization

Presented here are two isostructural uranyl coordination polymers [UO₂(EDO)(H₂O)]·H₂O (1) and [UO₂(BDO)(H₂O)]·2H₂O (2) (EDO^2-=ethylene-1,2-dioxamate; BDO^2-=butylene-1,2-dioxamate) with identical stepwise zigzag chain structure and distinct interchain hydrogen bonding interaction, prepared from hydrothermal reaction of DEEDO or DEBDO (DEEDO=diethyl ethylene-1,2-dioxamate; DEBDO=diethyl butylene-1,2-dioxamate) with uranyl ions. The monomeric uranyl-based fluorescence emissions of compounds 1 and 2 are red-shifted by about 6 and 5 nm respectively, compared to that of uranyl nitrate hexahydrate. Compound 1 has stronger emission than compound 2, but both their emissions exhibit triple-exponential decay. The photophysics of uranyl oxalate trihydrate was also investigated for comparison. The selective crystallization of compound 1 in alkaline solution was applied to the sequestration of uranyl ions, showing a kinetic preference.     

Stereoselective synthesis of (2S,3S,7S)-3,7-dimethylpentadec-2-yl acetate and propionate, the sex pheromones of pine sawflies

The stereoselective synthesis of (2S,3S,7S)-3,7-dimethylpentadec-2-yl acetate (2) and propionate (3) was accomplished by utilizing the cheap and easily available chiron (R)-4-methyl-δ-valerolactone (4). The key steps were chelation-controlled addition of Gilmann reagent to chiral β-alkoxy aldehyde 12 and the Cu(I)-catalyzed coupling of Grignard reagent with bromoester 5 in the presence of NMP.     

Photonic microwave phase shifter/modulator based on a nonlinear optical loop mirror incorporating a Mach-Zehnder interferometer

We realize a novel photonic microwave phase shifter/modulator based on a nonlinear optical loop mirror incorporating a Mach-Zehnder interferometer. A near-linear phase shifter exceeding 180 degrees and a phase modulation with 2.5 Gbit/s baseband signal are obtained for a 10 GHz microwave signal by this proposed device.     

Enhanced fluorescence of 3-(naphthalene-2-ylimino)-1-phenylbutan-1-one-Tb with 1,10-phenanthroline ternary system and its analytical application

A new Schiff base ligand: 3-(naphthalene-2-ylimino)-1-phenylbutan-1-one (NPB) was synthesized. Its fluorescence intensity with terbium(III) was greatly enhanced by the addition of 1,10-phenanthroline (Phen) in the chloroform solution. The mechanism of fluorescence enhancement was studied. The results indicate the formation of a ternary NPB-Phen-Tb complex. In the ternary system, Phen can transfer the energy absorbed by Phen and NPB to Tb(3+).