Reactions of hexaorganyldigermoxanes with O-trimethylsilyl carbamates

Hexa-n-butyl- and hexaisopentyldigermoxanes but not hexaphenyldigermoxane react with O-trimethylsilyl N,N-diethylcarbamate and trimethylsilyl piperidinocarboxylate to give O-triorganylgermyl carbamates.     

Quenching of singlet oxygen by phenols

The rate constants for the quenching of singlet oxygen by sterically hindered phenols were determined. It was observed that the rate constant for the quenching increases with a decrease in the ionization potential of phenols.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2132–2134, December, 1993.This work was supported by the Russian Foundation for Basic Research (Grant 93-03-5231).     

“One‐pot” synthesis of aromatic poly(1,3,4‐oxadiazole)s in novel solvents—ionic liquids

The new convenient method for the synthesis of high molecular weight aromatic poly(1,3,4‐oxadiazole)s (PODs) has been proposed. These polymers were prepared by “one‐pot” procedure from dicarboxylic acid and hydrazine's salt (sulfate, phosphate) or dicarboxylic acid dihydrazides. The mixture of ionic liquid and triphenyl phosphite was used both as a solvent and condensing agent. The polycyclization occurred at a sufficiently low temperature of 210 °C for 2–5 h and resulted in obtaining film‐forming PODs having inherent viscosities up to 0.9 dL/g and good thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 380–394, 2006     

A Simple Synthesis of 2‐{(Arylmethylidene)hydrazinylidene]‐3‐hydroxy‐4H‐furo[3,2‐c]pyran‐4(3H)‐ones

A simple synthesis of 2‐hydrazinylidene‐3‐hydroxy‐4H‐furo[3,2‐c]pyran‐4‐ones is described. A mixture of (isocyanoimino)(triphenyl)phosphorane, an aromatic aldehyde, and dehydroacetic acid (=3‐acetyl‐2‐hydroxy‐6‐methyl‐4H‐pyran‐4‐one) undergo a 1 : 1 : 1 addition reaction under mild conditions to afford the title compounds in excellent yields.     

Effects of tetrazolium chloride concentration,O<Subscript>2</Subscript>, and cell age on dehydrogenase activity of <Emphasis Type="Italic">Aspergillus niger</Emphasis>

The effects of triphenyl tetrazolium chloride (TTC) concentration, cell age, and presence of O₂ on the dehydrogenase activity of Aspergillus niger as measured by triphenyl formazan (TF) yield were investigated. The results indicated that increasing TTC concentration initially increased the TF yield and then decreased it. The maximum TF yield was observed at a TTC concentration of 30 g/L for young cells (4 d old) and 20 g/L for old cells (12 d old). Conducting the test under anaerobic conditions increased the TF yield. About 18% of the TF produced was converted back into TTC in the presence of oxygen. The relationship between dehydrogenase activity of A. niger (as measured by TF yield) and cell mass was found to be linear. A kinetic model describing the relationship between reaction rate (micromoles of TF formed per hour) and TTC concentration while accounting for substrate inhibition was developed, and the model constants were calculated. The optimum TTC-test conditions for dehydrogenase activity measurement of A. niger were a TTC concentration of 20 g/L, a pH of 9.0, a temperature of 55°C, an incubation time of 3 h, and anaerobic conditions.     

Reaction of small molecules O2, NO,CO, and the Naldini salt (PPh3)2MnBr2: Characterized by infrared spectroscopy,elemental analysis,and single-crystal X-ray diffraction

Addition of 2 equiv. of PPh₃ to MnBr₂ in tetrahydrofuran (THF) solution under N₂ atmosphere results in the formation of Naldini salt (PPh₃)₂MnBr₂ ( 1 ). Reaction of Complex 1 and O₂, NO, and CO (with reducing agent) leads to Complex (OPPh₃)₂MnBr₂ ( 2 ), (PPh₃)₂Mn(NO)Br₂ ( 3 ), and (PPh₃)₂Mn(CO)₃Br ( 4 ), respectively. Both Complexes 2 and 4 crystallize in the triclinic space group P-1 with a = 9.94 Å, b = 10.11 Å, c = 10.53 Å; α = 65.42°, β = 63.16°, and γ = 89.22° of 2 and a = 10.23 Å, b = 12.26 Å, c = 14.44 Å and α = 97.03°, β = 104.34°, and γ = 106.33° of 4 . The isoelectronic replacement of 3CO with 2NO yields the {Mn(NO)₂}⁸ species (PPh₃)₂Mn(NO)₂Br ( 5 ). The single crystal of 5 is in the monoclinic space group C2/c with a = 23.17 Å, b = 9.62 Å, c = 15.92 Å, and β = 114.91°. In the THF solution, Complex 5 serves as an NO source in the presence of NO trapping, Co(TPP), Co(TPP) = 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt(II).     

P/Rh比对PPh3-Rh/SiO2催化剂上丙烯氢甲酰化反应的影响

研究了P/Kh比对PPh3-Rh/SiO2催化剂上丙烯氢甲酰化反应性能的影响.结果表明,当P/Rh比为15时,丙烯氢甲酰化反应性能最好,丙烯转化率为25.9%,产物丁醛正异比为14,转换频率为241 h-1.PPh3-Rh/SiO2催化剂的固体31P核磁共振结果表明,在合成气气氛下,物理吸附的PPh3能够溢流到Rh/S...     

1H and 13C Nmr Determination of Polysubstituted Diphenylmethane Dimers Mechanism of Their Formation by Reduction of Polymethoxylated Benzophenones

Reduction of substituted benzophenones 1 with sodium borohydride and trifluoro-acetic acid yields diphenylmethanes 3 as well as dimers 5 and 6. the complete structure of these substituted diphenylmethane dimers 5 may be accurately determined by ¹H, ¹³C, 2D NMR analysis, and a mechanism for their formation is suggested.     

Synthesis,antimicrobial activity and high cell viability of copper derivatives of 2-thiouracil,purine-6-thione and 2,4,6-trimercaptotriazine

Reactions of copper(II) acetate with 2-thiouracil (tucH₂) and triphenyl phosphine (1:1:1 or 1:1:2 molar ratios) in methanol-acetonitrile/chloroform mixture yielded a light brown N,S-bridged dinuclear Cu^I complex, [Cu(PPh₃)₂(µ-N,S-tucH)Cu(PPh₃)₂Cl] 1, incorporating uninegative 2-thiouracilate. X-ray crystallography has shown that the crystals of complex 1 comprise a two component twin system and belong to the space group Ia. The major component 1a is about 77% and the minor component 1b is about 23%. One Cu is four-coordinate tetrahedral with center {CuP₂SCl} and the other Cu is three-coordinate distorted trigonal planar with {CuP₂N} center. Crystal data: 1, formula, C₇₆H₆₃ClCu₂N₂OP₄S; space group: Ia; monoclinic, a, 22.2638(9); b, 11.8050(4); c, 27.4455(10) Å; β, 113.358(5); R, 4.80%;173(2) K. The antimicrobial activities of dinuclear 1 as well as that of the previously reported 2-thiouracil, 2,4,6-trimercaptotriazine (tmtH₃) and purine-6-thione (purSH₂) complexes, [CuCl(κ¹-S-tucH₂)(PPh₃)₂] 2, [Cu₂Br₂(μ-S-tucH₂)₂(PPh₃)₂] 3, [Cu(tmtH₂)(PPh₃)₂] 4, [Cu₃Br₂(k¹-N,k¹-S,µ-S-tmtH₂)(PPh₃)₆] 5 and [Cu(k¹-N,k¹-S-purSH)(PPh₃)₂] 6, have been screened against gram negative, Escherichia coli (MTCC 119) and Shigella flexneri (MTCC 1457), gram positive, Enterococcus faecalis (MTCC 439) and Staphylococcus aureus (MTCC 740) microorganism. High percentage of cell viability (96–97%) is observed in some cases.     

Optical nonlinearities of tetracarbonyl-chromium triphenyl phosphine complex

The new tetracarbonyl — chromium-triphenyl phosphine complex was synthesized and characterized using ultraviolet(UV)-visible,Fourier transform infrared(FTIR),and nuclear magnetic resonance(NMR) techniques.The characterization results confirm the molecular structure of the new complex.The z-scan measurements were done by diode laser[continuous wave(CW)]to estimate the nonlinear optical parameter(X~3).The results led to calculate three parameters:the groundstate cross sections(σ_g),the excited-state cross sections(σ_(ex)),and thermo-optic coefficient of the new complex.This study indicated that our complex is a suitable for photonic applications.