Synthesis and Crystal Structure of the First Guanidinate Complex of Tetravalent Cerium

Reaction of Ce（O-t-Bu）2（NO3）2 and sodium guanidinate GuaNa （Gua-=TMS2NC（NC6H11）2-） in THF affords the first guanidinate Ce（IV） complex of Ce2（O-t-Bu）7（Guaˊ） （1, Gua-=（C6H11NH）C（NC6H 11）（NH）-）. It crystallizes in monoclinic, space group P21/n with a=15.2937（14）, b=17.8409（16）, c=19.0454（16）, β=97.713（2）°, V=5149.6（8）3 , Z=4, Mr=1014.38, Dc=1.308 g/cm3 , μ=1.787 mm-1 , F（000）=2104, S=1.015, R=0.0451 and wR=0.0901 （I 〉 2σ（I））. In the reaction the cleavage of TMS-N bonds happened unexpectedly.

Synthesis and structural analysis of titanium-μ-dinitrogen complex supported by di-anionic guanidinate ligands

The synthesis,characterization,and theoretical studies of titanium-μ-N_(2) complexes with di-anionic guanidinate ligands were reported as the first example of its kind.Thus,with(Me_(3)Si)_(2)N-guanidinate ligands,the mono-anionic guanidinate-supported titanium-μ-N2complex 1 was obtained.Then,reduction of 1 with potassium afforded the di-anionic guanidinate-supported titanium-μ-N_(2) complex 2 via cleavage of one N–Si bond of the(Me3Si)2N substituents in 1,changing the guanidinate ligands automatically from mono-anionic to di-anionic and remarkably lengthening the bond length of theμ-N_(2).Characteristic studies and DFT calculations were performed to reveal that the di-anionic guanidinate ligands stabilized the geometry of 2 and increased the charge density on the bridging dinitrogen.

Chelating Guanidinates for Dysprosium(Ⅲ) Single-Molecule Magnets

Two chelating guanidinate-based dysprosium(Ⅲ)complexes,namely the monomeric{(Me_(3)Si)_(2)NC(N^(i)Pr)_(2)}_(2)Dy(μ-CI)_(2)Li(THF)_(2) 1 and the dimeric[{(Me_(3)Si)_(2)NC(N^(i)Pr)_(2)}_(2)Dy(μ-CI)]_(2) 2,have been confirmed to be single-molecule magnets.Moreover,the alteration from 1 to 2 leads to an obvious mitigated quantum tunnelling of magnetization at zero field of the hysteresis loop and much enhanced magnetic relaxation barrier(up to 312 K).5%dilution with the yttrium(Ⅲ)analogue for 2 shows no clear change for the hysteresis,indicating the single-ion nature of the magnetic behavior.

A Novel Fracturing Fluid with High-Temperature Resistance for Ultra-Deep Reservoirs

Ultra-deep reservoirs play an important role at present in fossil energy exploitation.Due to the related high temperature,high pressure,and high formation fracture pressure,however,methods for oil well stimulation do not produce satisfactory results when conventional fracturing fluids with a low pumping rate are used.In response to the above problem,a fracturing fluid with a density of 1.2~1.4 g/cm^(3)was developed by using Potassium formatted,hydroxypropyl guanidine gum and zirconium crosslinking agents.The fracturing fluid was tested and its ability to maintain a viscosity of 100 mPa.s over more than 60 min was verified under a shear rate of 1701/s and at a temperature of 175℃.This fluid has good sand-carrying performances,a low viscosity after breaking the rubber,and the residue content is less than 200 mg/L.Compared with ordinary reconstruction fluid,it can increase the density by 30%~40%and reduce the wellhead pressure of 8000 m level reconstruction wells.Moreover,the new fracturing fluid can significantly mitigate safety risks.

Theoretical investigation on organolanthanide guanidinate complexes

Density functional theory (DFT) calculations were carried out on the compounds Cp2Ln-guan for Ln=Y, Lu, Yb, Dy and Gd, [guan=(iPrN)2CN(iPr)2]. The results were compared with the X-ray structures that were available from the literature; the calculations reproduced quite well the experimental structural features in these complexes exhibiting distorted tetrahedron geometry. The calculated evolution of the Ln-guan bond as a function of the cation showed that lanthanide-ligand distances increased with the increa...

Syntheses of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands and their catalytic activity toward the hydrophosphonylation reaction of aldehydes and ketones

A series of bimetallic lanthanide bis(amido) complexes stabilized by bridged bis(guanidinate) ligands {[(Me3Si)2N]2Ln[(RN)2-CN(CH2)2]}2 [R=iPr, Ln=Sm(1), Yb(2), Y(3); R=cyclohexyl(Cy), Ln=Sm(4), and Yb(5)] were synthesized through the metathesis reactions of {Ln(μ-Cl)[N(Si Me3)2]2(THF)}2(Ln=Sm, Yb, Y) with lithium guanidinate {Li[(RN)2CN(CH2)2]}2(R=iPr, Cy), the latter of which was generated in situ by the reaction of carbodiimides with lithium amides. Complexes 1–5 were well characterized by elemental analyses, IR spectra, and(for Complex 3) NMR spectroscopy. The solid-state molecular structures of all of the complexes were determined by single-crystal X-ray analyses with the exception of Complex 3, which showed similar unsolvated centrosymmetric dinuclear structures. Each of the lanthanide centers is four-coordinated with two nitrogen atoms from a guanidinate ligand and two nitrogen atoms from two amido groups. The piperazidine rings adopt chair conformations in all cases. These organolanthanide complexes were found to be efficient catalysts for the hydrophosphonylation reaction of various aldehydes and unactivated ketones and to afford ?-hydroxyphosphonates in high yields under low catalyst loading(0.1 mol%) in a short reaction time.

Synthesis and Structural Characterization of Alkali Metal Guanidinates

Reactions of 1,3-diisopropylcarbodiimide with alkali metal amides, MN（SiMe3）2 （M=Li or Na） in hexane or THF produced the alkali metal guanidinates { （i-PrN）2C [N（SiMe3）2]Li }2 （1） and { （i-PrN）2C[N（SiMe3）2]Na（THF） } 2 （2） in nearly quantitative yields. Both complexes 1 and 2 were well characterized by elemental analysis, IR spectra, ^1H and ^13C NMR spectra, and X-ray diffraction. It was found that the guanidinates adopt different coordination modes in these complexes.

Synthesis and Characterization of Bis（guanidinate） Zirconium Complexes

Addition of one equivalent of LiN（i-Pr）2 or LiN（CH2）5 to carbodiimides, RN=C=NR [R=cyclohexyl （Cy）, isopropyl （i-Pr）], generated the corresponding lithium of tetrasubstituted guanidinates {Li[RNC（N R^′2）NR]（THF）}2 [R=i-Pr, N R^′2=N（i-Pr）2 （1）, N（CH2）5 （2）; R=Cy, N R^′2=N（i-Pr）2 （3）, N（CH2）5 （4）]. Treatment of ZrCl4 with freshly prepared solutions of their lithium guanidinates provided a series of bis（guanidinate） complexes of Zr with the general formula Zr[RNC（N R^′2）NR]2Cl2 [R=i-Pr, N R^′2=N（i-Pr）2 （5）, N（CH2）5 （6）; R=Cy, N R^′2=N（i-Pr）2 （7）, N（CH2）5 （8）]. Complexes 1, 2, 5-8 were characterized by elemental analysis, IR and ^1H NMR spectra. The molecular structures of complexes 1, 7 and 8 were further determined by X-ray diffraction studies.

Synthesis of 4-methyl Guanidine Butyric Acid

N-methyl pyrrolidone,hydrochloric acid and thiourea dioxide were adopted as the raw material,and 4-methyl guanidine butyric acid was synthesized through two-step reaction.The optimum synthesis condition for the first step was as follows：n（N-methyl pyrrolidone）∶n（10% HCl）= 1∶2.0,reaction temperature 135 ℃,reaction time 5 h;at that moment,the yield of intermediate 4-methyl-amino butyric acid hydrochloride was 72.89%.The optimum synthesis condition for the second step was as follows：n（4-methyl-amino butyric acid hydrochloride）∶n（thiourea dioxide）= 1∶2.0,reaction temperature 25 ℃,reaction time 12 h,at that moment,the yield of target product was 82.68%.Structure characterization on the intermediates and the target products were carried out through Fourier transform infrared spectroscopy and elemental analysis.

Synthesis and Crystal Structure of Bis(N,N'- cyclohexyl-N''-bis(trimethylsilyl)samarium Chloride

The reaction of [(SiMe3)2NC(NC6H11)2]Li with SmCl3 in 2:1 molar ratio in THF gave bis(N,N-cyclohexyl-N创-bis(trimethylsilyl)samarium chloride, [(SiMe3)2NC(NC6H11)2]Sm(m- Cl)2Li(THF)2 1 in 85% isolated yield as pale-yellow crystals. Complex 1 was structurally characte- rized by single-crystal X-ray diffraction analysis at 289(2) K. It crystallizes in monoclinic, space group C2/c with a = 26.886(3), b = 13.677(2), c = 19.465(3) ? b = 120.26(1), V = 6182(2) ?, Z = 4, Mr = 1105.84, Dc = 1.188 g/cm3, F(000) = 2340 and m(MoKa) = 1.150 mm-1. The structure was refined to R = 0.0378 and wR = 0.0885 for 4342 observed reflections with I > 2s(I). The coordination geometry of samarium ion can be best described as a distorted pseudooctahedron.

One New Schiff Base Complex with One in Situ Synthesized Ligand:Synthesis and Structure

One new Ni（Ⅱ） complex [Ni（H2L）]Cl（H2O）3 based on one in-situ synthesized Schiff base ligand H3L （H3L = bis（benzyl-2-pyridylidene）-diaminoguanidine） was prepared and structurally characterized by single-crystal X-ray diffraction method. The complex crystallizes in the monoclinic system, space group C2/c with a = 27.944（7）, b = 7.7405（19）, c = 25.999（7） ,A, β = 115.545（2）°, V = 5074（2） A^3, Mr = 566.69, Z = 8, Dc = 1.484 g/cm^3, F（000） = 2352,μ（MoKα） = 0.912 mm^-1, R = 0.0594 and wR = 0.1477 for 5145 observed reflections （1 〉 2σ（I））. The complex exhibits one mononuclear structure in which the Ni（Ⅱ） atom adopts a [NiN4] pseudo-planar square geometry. Interestingly, along the b axis, each two neighboring [Ni（H2L）]^＋ units by an inverse center form pairs of molecules through the intermolecular benzene-pyridine π…π interactions.

Guanidine分子在燃料电池用阴离子交换膜中的应用

以壳聚糖(CS)和2,3-环氧丙基三甲基氯化铵(GTA)为原料,制备季铵化壳聚糖(QCS),将其与小分子游离胍(Guanidine)共混,借助戊二醛(GA)的化学交联作用,将季铵化壳聚糖中的氨基以及胍中的氨基交联,形成网状结构,由此制得含有不同含量Guanidine分子的交联QCS-G阴离子交换膜。实验过程中,对该膜的含水率、溶胀度、力学强度、电导率及耐碱稳定性等进行了详细的考察。结果表明,游离胍的引入可有效地提高膜的电导率和耐碱稳定性,同时降低了膜的溶胀度及含水率。其中小分子游离胍质量分数为2.5%的膜(QCS-G2.5%)在70℃时的电导率可达到6.58×10^(-2)S/cm;在10 mol/L NaOH溶液中浸渍72 h后该膜70℃测得的电导率损失仅为3.8%,离子交换量损失仅为3.82%,表明该膜的耐碱性能较好。

Copper solvent extraction from alkaline cyanide solution with guanidine extractant LIX 7950

The use of the guanidine extractant LIX 7950 extracting copper and cyanide from alkaline cyanide solution was investigated.The extraction of copper and cyanide under different initial copper and extractant concentrations was examined and the stoichiometric extraction constant of Cu(CN)32- with LIX 7950 was calculated.Both the distribution coefficient and the stoichiometric extraction constant of Cu(CN)3 2-with LIX 7950 decrease when the temperature is varied from 25℃to 45℃, indicating the extraction process is exothermic.The calculated enthalpy change of the reaction(-HΘ)is about-190 kJ/mol.The copper extraction isotherms under different molar ratios of cyanide to copper are established.The preferential extraction of Cu(CN)32- over Cu(CN)4 3-and CN -has been confirmed and a high cyanide-to-copper molar ratio tends to suppress copper loading. The loaded copper and cyanide can be stripped efficiently by the moderately strong NaOH solutions(0.5-1.0 mol/L)and the presence of NaCN in the stripping solution facilitates copper stripping.

Effects of aminoguanidine on nitric oxide production induced by inflammatory cytokines and endotoxin in cultured rat hepatocytes

AIM: To study the effects of aminoguanidine (AG) and two L-arginine analogues N(omega)-nitro-L-arginine methyl ester (L-NAME) and N(omega)-nitro-L-arginine (L-NNA) on nitric oxide (NO) production induced by cytokines (TNF-alpha, IL-1 beta, and IFN-gamma) and bacterial lipopolysaccharide (LPS) mixture (CM) in the cultured rat hepatocytes, and examine their mechanisms action. METHODS: Rat hepatocytes were incubated with AG, L-NAME, L-NNA, Actinomycin D (ActD) and dexamethasone in a medium containing CM (LPS plus TNF-alpha, IL-1 beta, and IFN-gamma) for 24h. NO production in the cultured supernatant was measured with the Griess reaction. Intracellular cGMP level was detected with radioimmunoassy. RESULTS: NO production was markedly blocked by AG and L-NAME in a dose-dependent manner under inflammatory stimuli condition triggered by CM in vitro. The rate of the maximum inhibitory effects of L-NAME (38.9%) was less potent than that obtained with AG(53.7%, P 【 0.05). There was no significant difference between the inhibitory effects of AG and two L-arginine analogues on intracellular cGMP accumulation in rat cultured hepatocytes. Non-specific NOS expression inhibitor dexamethasone (DEX)and iNOS mRNA transcriptional inhibitor ActD also significantly inhibited CM-induced NO production. AG(0.1 mmol x L(-1)) and ActD (0.2 ng x L(-1)) were equipotent in decreasing NO production induced by inflammatory stimuli in vitro, and both effects were more potent than that induced by non-selectivity NOS activity inhibitor L-NAME (0.1 mmol x L(-1)) under similar stimuli conditions (P【0.01). CONCLUSION: AG is a potent selective inhibitor of inducible isoform of NOS,and the mechanism of action may be not only competitive inhibition in the substrate level, but also the gene expression level in rat hepatocytes.

Denaturing Effects of Urea and Guanidine Hydrochloride on Hyperthermophilic Esterase from Aeropyrum pernix K1

The changes in the activity and the conformation of the hyperthermophilic esterase derived from aerobic thermophilic Aeropyrum pernix K1 （ APE1547 ） were studied during denaturation by guanidine hydrochlofide （ GdnHC1 ） and urea. The denaturation course of APE1547 was followed by the steady-state and time resolved fluorescence methods. An increase in the denaturant concentration in the denatured system can significantly enhance the inactivation and unfolding of APE1547. The enzyme can be completely inactivated with a urea concentration of 2.7 mol/L or a GdnHCl concentration of 7.5 mol/L. The fluorescence emission maximum of the enzyme protein red shifts in magnitude to a maximum value（355 nm） when the concentration of GdnHCl is 5.1 mol/L. The experimental results indicate that APE1547 has a high resistance to urea. Unfolding of APE1547 in GdnHCI（4. 2-6.0 mol/L） was shown to be an irreversible process. The present results indicate that the ion pairs in this protein may be a key factor for the stability of this esterase.

Synthesis and NHE1 inhibitory activity of ligustrazine derivatives

A series of novel derivatives of ligustrazine linked with substituted benzoyl guanidine were synthesized. These compounds have not been reported in literature, and their chemical structures were confirmed by IR, ^1H NMR and MS. The results of NHE1 inhibitory activity test showed that compounds I2, I3, I4, I6, and I7 possess more potent NHE1 inhibitory activity than cariporide.

I-123 metaiodobenzylguanidine imaging for predicting ventricular arrhythmia in heart failure patients

Compared to antiarrhythmic drugs, implantable cardioverter defibrillator （ICD） leads to a more significant im- provement in preventing ventricular arrhythmia in heart failure patients. However, an important question has been raised that how to select appropriate patients for ICD therapy. 1-123 metaiodobenzylguanidine （MIBG） planar and SPECT imaging have shown great potentials to predict ventricular arrhythmia in heart failure patients by as- sessing the abnormalities of the sympathetic nervous system. Clinical trials demonstrated that several parameters measured from 1-123 MIBG planar and SPECT imaging, such as heart-to-mediastinum ratio, washout rate, defect score, and innervation/perfusion mismatch, predicted ventricular arrhythmias in heart failure patients. This paper introduces the current practice of ICD therapy and reviews the technical background of 1-123 MIBG planar and SPECT imaging and their clinical data in predicting ventricular arrhythmia.

FLAME RETARDANT OF GUANIDINE CONDENSED PHOSPHATE (GCP) FOR WOOD

GCP and APP were used as flame retardants for poplar wood and larch wood,and their flame retardancy(OI), permeability (Surface electron spectroscopy), water-re pellency and corrosion toward nail evaluated. The results showed that GCP is in advance of APP. From the thermal analysis and char composition analysis, it is concluded that GCP mainly functions in condensed phase.

The Antiviral Action of Polyhexamethylene Guanidine Derivatives

Although the PHMG （polyhexamethylene guanidine） and other oligomer guanidines are known as highly efficient biocides against a broad spectrum of microorganisms and eukaryotic cells, the cell protection by PHMG derivatives has been established firstly in this study. The antiviral protection was also exhibited after 15 min pretreatment of different cell cultures with low-concentration of PHMG salts. Monolayers of the continuous bovine tracheal cells culture （TCC） and primary culture of chicken embryo fibroblasts （FCE） were treated with aqueous solutions of PHMG chloride salts or PHMG succinate. The molecules of PHMG polycation adhered to the plasma membrane of the cells tested as they were treated with PHMG for 15-30 min. The viral material was added to the cell cultures after the wash-out carried out twice to rid of unbound PHMG. The viruses of Equine herpesvirus type 1, Rhinotracheitis infectious bovine and Equine infectious anemia virus were used. The protective effect from the cytopathic action of herpes and retroviruses was exhibited after 15 min pretreatment of cell monolayer with PHMG chloride at the TCC concentrations of 10^-3 - 10^-2% and FCE concentrations of 10^-5 - 10^-4%. The unique antiviral properties of PHMG salts represented in our research had never been shown before.

Polymer Supported Synthesis of Multi-substituted Pyrimidine-4-one Derivatives via Pbf-activated Thiourea

Efficient polymer supported synthesis of multi-substituted pyrimidine-4-one derivatives was described. Target products were produced from fluorenylmethoxycarbonyl（Fmoc） protected β-amino acid loaded on hydro- xymethyl resin through deprotection, N-alkylation, guanidine formation, and cleavage of 2,2,4,6,7-pentamethyl dihy-drobenzofuran-sulfonyl（Pbf） by trifluoracetic acid（TFA） followed with cyclization. The procedure has the advantages of easy operation, mild reaction conditions, and forming multiple substituents.