A new mixed-metal sulfido incomplete cubane cluster [(MoCuS3) (O) (μ-dtp) (PPh3)3] Cdtp = S2P (OC2H5)2] has been prepared by reaction of (NH4)2MoOS3 with Cu(dtp) (PPh3)2 in dimethylformamide solution. It crystallizes...A new mixed-metal sulfido incomplete cubane cluster [(MoCuS3) (O) (μ-dtp) (PPh3)3] Cdtp = S2P (OC2H5)2] has been prepared by reaction of (NH4)2MoOS3 with Cu(dtp) (PPh3)2 in dimethylformamide solution. It crystallizes in the triclinic space group P1, a = 13.810(5), b = 19. 753(5), c=11. 719(4) A. α=99. 42(2), β=107. 24(3),γ=88. 05(3)°, V = 3012(2)A3, Dc = l. 51g/cm3and Z = 2. Final R=0. 046, Rw = 0. 056 for 7700 unique intensity data(I≥3σ(I)). The central unit [MoCu3S3]3+ can be described as a distorted incomplete cube with one missing corner. The Mo atom is tetrahedrally coordinated by three μ3-S atoms and one terminal O atom. Two Cu atoms are tetrahedrally coordinated whereas the third Cu atom has a highly distorted trigonal environment. The mean Mo - Cu bond length is 2. 752A. The Cu...Cu distances are in the range of 3. 200(1) -3. 740(1) A which are too long to form bonds.展开更多
In this study,based on two attractive energetic compounds pentazole(PZ) and tetraazacubane(TAC),a new family of high energy and high nitrogen compounds pentazolyltetraazacubanes were designed.Then,a different number o...In this study,based on two attractive energetic compounds pentazole(PZ) and tetraazacubane(TAC),a new family of high energy and high nitrogen compounds pentazolyltetraazacubanes were designed.Then,a different number of NH2 or NO2 groups were introduced into the system to further adjust the property.The structures,properties,and the structure-property relationship of designed molecules were investigated theoretically.The results showed that all nine designed compounds have extremely high heat of formation(HOF,1226-2734 kJ/mol),good density(1,73-1.88 g/cm3),high detonation velocity(8.30-9.35 km/s),high detonation pressure(29.8-39.7 GPa) and acceptable sensitivity(△V:41-87 A3).These properties could be effectively positive adjusted by replacing one or two PZ rings by NH2 or/and NO2 groups,especially for the energy and sensitivity performance,which were increased and decreased obviously,respectively.As a result,two designed pentazolyltetraazacubanes were predicted to have higher energy and lower sensitivity than the famous high energy compound in use 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane,while two others have better co mbination property than 1,3,5-Trinitro-1,3,5-triazacyclohexane.In all,four new pentazolyltetraazacubanes with good combination performance were successfully designed by combining PZ with TAC,and the further property adjustment strategy of introducing a suitable amount of NH2/NO2 groups into the system.This work may help develop new cage energetic compounds.展开更多
A new Mn2Ni2 cubane complex has been synthesized and characterized by single-crystal X-ray diffraction,FT IR spectra and elemental analysis.The title compound [MnIII2NiII2（hmp）4（N3）4（O2CR）2]（hmp-is the anion of...A new Mn2Ni2 cubane complex has been synthesized and characterized by single-crystal X-ray diffraction,FT IR spectra and elemental analysis.The title compound [MnIII2NiII2（hmp）4（N3）4（O2CR）2]（hmp-is the anion of 2-pyridinemethanol and O2CR-is α-na-phthaleneacetate）crystallizes in the monoclinic system,space group P21/c with a = 10.519（5）,b = 22.109（10）,c = 23.235（9）,β = 106.096（17）o,C48H42Mn2N16Ni2O8,Mr = 1198.28,V = 5192（4）3,Dc = 1.533 g/cm3,F（000）= 2448,μ = 1.258 cm1,Z = 4,the final R = 0.0875 and wR = 0.2020 for 3398 reflections with I 2σ（I）.X-ray diffraction analysis reveals that each Mn（III）center is octahedrally coordinated by two nitrogen atoms of azide anions and three oxygen atoms from three 2-pyridinemethanol anion ligands together with one oxygen atom from naphthaleneacetate.Each Ni（II）is octahedrally coordinated by two nitrogen atoms of 2-pyridinemethanol anion ligands as well as three oxygen atoms from three 2-pyridinemethanol anion ligands and one oxygen atom from naphthaleneacetate.展开更多
Molecular materials possessing switchable magneto-optical properties are of great interest due to their potential applications in spintronics and molecular devices.However,switching their photoluminescence(PL)and sing...Molecular materials possessing switchable magneto-optical properties are of great interest due to their potential applications in spintronics and molecular devices.However,switching their photoluminescence(PL)and single-molecule magnet(SMM)behavior via light-induced structural changes still constitutes a formidable challenge.Here,a series of cubane structures were synthesized via self-assembly of 9-anthracene carboxylic acid(HAC)and rare-earth ions.All complexes exhibited obvious photochromic phenomena and complete PL quenching upon Xe lamp irradiation,which were realized via the synergistic effect of photogenerated radicals and[4+4]photocycloaddition of the AC components.The quenched PL showed the largest fluorescence intensity change(99.72%)in electron-transfer photochromic materials.A reversible decoloration process was realized via mechanical grinding,which is unexpectedly in the electron-transfer photochromic materials.Importantly,an SMM behavior of the Dy analog was observed after room-temperature irradiation due to the photocycloaddition of AC ligands and the photogenerated stable radicals changed the electrostatic ligand field and magnetic coupling.Moreover,based on the remarkably photochromic and photoluminescent properties of these compounds,2 demos were applied to support their application in information anti-counterfeiting and inkless printing.This work,for the first time utilizing the simultaneous modulation of photocycloaddition and photogenerated radicals in one system,realizes complete PL quenching and light-induced SMM behavior,providing a dynamical switch for the construction of multifunctional polymorphic materials with optical response and optical storage devices.展开更多
We report the stepwise in-situ manipulation of a nickel cubane nanocluster capped with a specially designed multidentate ligand [Ni^(Ⅱ)_(4)(HL)_(3)(CH_(3)O)(CH_(3)OH)_(3)](CH_(3)COO)(Ni_(4),H_(3)L=(E)-3-((2-hydroxy-3...We report the stepwise in-situ manipulation of a nickel cubane nanocluster capped with a specially designed multidentate ligand [Ni^(Ⅱ)_(4)(HL)_(3)(CH_(3)O)(CH_(3)OH)_(3)](CH_(3)COO)(Ni_(4),H_(3)L=(E)-3-((2-hydroxy-3-mehoxybenzylidene)amino)propane-1,2-diol) to firstly [Ni^(Ⅱ)_(4)(HL)_(3)(CH_(3)O)(CH_(3)OH)_(2)(H_(2)O)](CH_(3)COO)(Ni4-1min) and finally to [Ni^(Ⅱ)_(4)(HL)_(3)(CH_(3)O)(H_(2)O)_(3)](CH_(3)COO)Ni4-20h)during the urea electrolysis.A combination of mass spectrometry,single crystallography and pair distribution function were employed to analyze the structural correlations of this catalyst in crystal/solution/gas phases for confirming the dynamic ligand replacement while preserving the cubic Ni4 core during catalysis.The key feature of their structures is that:(i)three ligands wrap the Ni_(4)O_(4)cubane center on one side forming the rounded outside of a calix;(ii)the opposite flat side containing labile methanol as the active site.This structure facilitates the binding of the substrate to the active central nickel atoms during catalysis.Furthermore,due to the different modes of packing,the structure of Ni4-20 h sustains two-dimensional(2D)net of open space while the structures of Ni4 and Ni4-1 min have only closed void inaccessible to solvent molecules or ions.Interestingly,the overpotential initially decreased(up to 45 min)until it is stabilized.The result showed a low potential of 1.32 V(urea oxidation reaction(UOR))at 10 mA·cm^(-2)as reflected in the Gibbs free energy decrease of~0.4 eV from Ni4 to Ni4-20 h.This work demonstrates a convincing approach for elucidating the exact nature of the active clusters in electrocatalytic process,and confirms that in-situ modification of electrode materials might alter the direct electronic interaction between substrate and active sites in improving the catalytic performance.展开更多
Single cubane-like clusters, MFe_3S_4(R_2dtc)_5 (M=Mo, R_2=—(CH_2)_4—, Bz_2; M=W, R_2=Me_2, —(CH_2)4—; dtc=dialkyldithiocarbamate) were synthesized by assembly reaction of (NH_4)_2MS_4 (M=Mo, W), FeCl_2 with R_2dt...Single cubane-like clusters, MFe_3S_4(R_2dtc)_5 (M=Mo, R_2=—(CH_2)_4—, Bz_2; M=W, R_2=Me_2, —(CH_2)4—; dtc=dialkyldithiocarbamate) were synthesized by assembly reaction of (NH_4)_2MS_4 (M=Mo, W), FeCl_2 with R_2dtcNa (or NH_4) in DMF. The structure, IR, EPR and cyclic voltammogram are described and discussed. MoFe_3S_4(C_4H_8dtc)_5 was also obtained from the conversion of linear cluster Fe(DMF)_6[(FeCl_2)_2MoS_4] in the presence of C_4H_8dtc NH_4. Both clusters MoFe_3S_4(C_4H_8dtc)_4·2C_2H_5CN and WFe_3S_4(C_4H_8dtc)_5·2DMF crystallize in the monoclinic space group C2/c with a=12.544(2), (Mo-cluster), 12.533(4) (W-cluster); b=20.478(4), 20.121(6); c=19.582(7), 19.659(2);β=102.82(2), 102.96(3)°; and Z=4, 4. Their structures were refined to R=0.057 and 0.064 with use of 2690 and 2179 reflections (ι>3Q(I)), respectively. Many similarities in structure for Mo and W clusters indicate that both Mo and W play a very similar role in the clusters.展开更多
In mass spectrometry, fragments with a mass higher than the original molecular ion provide valuable insights into the molecular structure and can guide the assembly and disassembly processes for chemical synthesis. He...In mass spectrometry, fragments with a mass higher than the original molecular ion provide valuable insights into the molecular structure and can guide the assembly and disassembly processes for chemical synthesis. Here, we report such an example and following up by modifying the solvothermal reaction conditions (temperature and time) it is possible to isolate the high mass species in crystalline form. [Zn_(4)L_(4)Cl_(4)] (Zn_(4)L_(4), L = N-methylbenzimidazole-2-methanolate) has a boat-like Zn_(4)O_(4) core but electrospray ionization mass spectrometry (ESI-MS) of the solution of its crystals shows higher mass peaks of Zn_(5)L_(5), Zn_(5)L_(6) and Zn_(6)L_(6) species. Thus, both disassembly and reassembly are highly probable processes. Consequently, [Zn(HL)_(2)Cl_(2)] (Zn1, L = N-methylbenzimidazole-2-methanolate), [Zn_(4)L_(6)Cl_(2)] (Zn_(4)L_(6), L = N-methylbenzimidazole-2-methanolate) and [Zn_(6)L_(6)Cl_(4)(CH_(3)O)_(2)] (Zn_(6)L_(6), L = N-methylbenzimidazole-2-methanolate) were prepared. The results of multistage ESI-MS of their dissolved crystals led to a proposed mechanism of their formation in the gas phase as follows: [Zn_(3)L_(4)] through [ZnL] → [ZnL(HL)] → [Zn(HL)_(2)] → [Zn_(2)L] → [Zn_(2)L_(2)] → [Zn_(2)L_(3)]. The mechanism was derived in conjunction with Gibbs free energies calculated using DFT of the fragments observed in the ESI-MS of Zn_(4)L_(4), Zn_(4)L_(6) and Zn_(6)L_(6). This work reveals the complex of chemical reactions, involving fragmentation and unexpected combination, under mass spectrometry condition which allows one to synthesize the observed transients, leading to mechanism of formation by correlation of solid-state/solution structural information.展开更多
Three types of unit combinations, FeS2Fe + FeS2Fe, FeS2Fe + MoS2Fe and MoS2Mo + MoS2Mo, lead to Fe4S4, MoFe3S4 and Mo2Fe2S4 cubane-like clusters, respectively. A new doubly bridged single cubane cluster [Mo2Fe2S4(C4H8...Three types of unit combinations, FeS2Fe + FeS2Fe, FeS2Fe + MoS2Fe and MoS2Mo + MoS2Mo, lead to Fe4S4, MoFe3S4 and Mo2Fe2S4 cubane-like clusters, respectively. A new doubly bridged single cubane cluster [Mo2Fe2S4(C4H8dtc)6]·3.5C2H2Cl4 has been obtained and its structure is discussed.展开更多
The reaction of CuI with cinchonine （an organic donor-acceptor chromophore） afforded a homochiral 3D diamondoid network [Cu4I4（cinchonine）2]n （1） containing a cubane cluster （Cu4I4） as a connecting node. This ...The reaction of CuI with cinchonine （an organic donor-acceptor chromophore） afforded a homochiral 3D diamondoid network [Cu4I4（cinchonine）2]n （1） containing a cubane cluster （Cu4I4） as a connecting node. This is the first homochiral coordination polymer with diamondoid nets containing a cluster as a connecting note. Its thermal stability and solid state optical properties such as fluorescence, circular dichroism and second-harmonic generation response were also reported.展开更多
A novel (Me 3PhCH 2N) 2[MoFe 4S 4(SC 6H 11 ) 7] cubane like cluster was obtained from a reaction system including (NH 4) 2MoS 4, FeCl 2 and NaSC 6H 11 in methanol, and characterized by X ray crystallography. The title...A novel (Me 3PhCH 2N) 2[MoFe 4S 4(SC 6H 11 ) 7] cubane like cluster was obtained from a reaction system including (NH 4) 2MoS 4, FeCl 2 and NaSC 6H 11 in methanol, and characterized by X ray crystallography. The title compound crystallizes in triclinic space group P 1 with a =1.523 1(3), b =1.610 5(3), c =1.838 3(4) nm, α =77.18 (3)°, β =75.17(3)°, γ =64.60 (3)°, and Z =2. Also included in this paper are the discussions on the variation of the reaction products obtained from the participation of cyclohexylthiolate and on the changes of the structural features of the products.展开更多
The tetranuclear cubane-like complex, [NiL（EtOH）]4·0.5EtOH （1） with tridentate Schiff base ligand （H2L= 2-Hydroxymethyl-N-salicylideneaniline） has been synthesized and its crystal structure and spectroscopi...The tetranuclear cubane-like complex, [NiL（EtOH）]4·0.5EtOH （1） with tridentate Schiff base ligand （H2L= 2-Hydroxymethyl-N-salicylideneaniline） has been synthesized and its crystal structure and spectroscopic properties have been studied. The complex consists of a tetranuclear （NiO）4 cubane core, of which four nickel（Ⅱ） ions are bridged by μ3-alkoxide group and each nickel（Ⅱ） ion is coordinated to three μ3-alkoxide oxygen atoms, one imino nitrogen atom and one phenoxide oxygen atom from Schiff base ligand, and further ligated by one EtOH molecule, completing a distorted octahedral geometry.展开更多
On June 20,the 7th China-Latin America and Caribbean Think Tank Forum was held in Beijing.The forum carried the theme“Working Together to Build a China-LAC Community with a Shared Future.”Assistant Foreign Minister ...On June 20,the 7th China-Latin America and Caribbean Think Tank Forum was held in Beijing.The forum carried the theme“Working Together to Build a China-LAC Community with a Shared Future.”Assistant Foreign Minister Miao Deyu attended the opening ceremony and delivered remarks.Leonel Caraballo Maqueira,Vice President of the Cuban Diplomatic Academy,and Martin Charles,Ambassador of Dominica to China and Representative of the Latin American and Caribbean Diplomatic Corps in China,attended the meeting and delivered speeches.展开更多
[Objective] The artificial breeding technology of Cuban fly （Lixophaga diatraeae） and its parasitic ability on Chilo infuscatellus was studied.[Method] Through artificial inoculation experiment,the effects of differ...[Objective] The artificial breeding technology of Cuban fly （Lixophaga diatraeae） and its parasitic ability on Chilo infuscatellus was studied.[Method] Through artificial inoculation experiment,the effects of different inoculation proportions between maggot and Galleria mellonella larvae on the growth and development of Cuban fly were studied.Through indoor low temperature storage tests,effects of different temperatures on the emergence rate of Cuban fly were studied;and the effects of different ecological conditions （humidity,sunshine） on the emergence rate of Cuban fly and its parasitic ability on Chilo infuscatellus were studied through indoor and field comparison experiment.[Result] The optimum inoculation proportions between maggot and G.mellonella larvae were 3：1 and 4：1,pupa production amounts were 279 and 327,respectively;short storage under the temperature of 10℃ had small effect on the emergence rate of Cuban fly,while the storage time should not exceed 15 d.Indoor and field parasitic test showed that Cuban fly had strong parasitic ability on C.infuscatellus,the parasitic rate reached 33.3%-50.0%;the parasitic rates during elongation stage and maturation stage were 47.8% and 41.7%,respectively,while they almost could not parasite during seedling stage.[Conclusion] The results provided scientific basis for artificial breeding of Cuban fly in large scale and its field release technology.展开更多
The title compound [Er4(m3-OH)4(Hpro)4(pro)2(H2O)7](ClO4)67H2O has been synthesized and its crystal structure was determined by X-ray diffraction study. It crystallizes in rhombohedral, space group R3, a = b = c = 12....The title compound [Er4(m3-OH)4(Hpro)4(pro)2(H2O)7](ClO4)67H2O has been synthesized and its crystal structure was determined by X-ray diffraction study. It crystallizes in rhombohedral, space group R3, a = b = c = 12.7812(2) ? a = b = g = 100.067(1), V = 1978.19(5) 3, Z = 1, Mr = 2274.77, Dc = 1.909 g/cm3, F(000) = 1112, m = 4.506mm-1, the final R = 0.0405 and wR = 0.1068 for 3711 observed reflections (I > 2s(I)). Four Er3+ ions and four m3-OH display a Er4O4 cubane structural motif. Each proline interconnects two Er3+ ions.展开更多
AIM： To investigate the prevalence of vacuolating cytotoxin （vacA）, cytotoxin associated gene A （cagA） and blood adhesion binding antigen （babA2） genotypes of Helicobacter pylori （H pylori） isolates from Cuba...AIM： To investigate the prevalence of vacuolating cytotoxin （vacA）, cytotoxin associated gene A （cagA） and blood adhesion binding antigen （babA2） genotypes of Helicobacter pylori （H pylori） isolates from Cuban dyspeptic patients. METHODS： DNA was extracted from Hpylori-positive cultures taken from 130 dyspeptic patients. Genotyping was performed by PCR, using specific primers for vacA （s1, s2, m1, m2）, cagA and babA2 genes. Endoscopic observations and histological examinations were used to determine patient pathologies. RESULTS： vacA alleles s1, s2, m1 and m2 were detected in 96 （73.8%）, 34 （26.2%）, 75 （57.7%） and 52 isolates （40%）, respectively, while the cagA gene was detected in 95 isolates （73.2%）. One hundred and seven isolates （82.3%） were babA2-positive. A significant correlation was observed between vacAs1m1 and cagA and between vacAs1ml and babA2 genotypes （P 〈 0.001 and P 〈 0.05, respectively） and between babA2 genotype and cagA status （P 〈 0.05）; but, no correlation was observed between vacAsl and babA2 genotypes. Eighty five （65.4%） and 73 （56.2%） strains were type 1 （vacAsl-cagA-positive） and ＂triplepositive＂ （vacAs1-cagA-babA2-positive）, respectively, and their presence was significantly associated with duodenal ulcer （P 〈 0.01 and P 〈 0.001, respectively）. CONCLUSION： The distribution of the main virulence factors in the Cuban strains in this study resembled that of the Western-type strains, and the more virulent H pylori isolates were significantly associated with duodenal ulcer, ulcer disease being the worst pathology observed in the group studied.展开更多
Aim： To investigate whether oral treatment with D-004, a lipid extract of the Cuban royal palm fruit, produces antioxidant effects in the prostate tissue of normal and testosterone （T）-treated rats. Methods： In ou...Aim： To investigate whether oral treatment with D-004, a lipid extract of the Cuban royal palm fruit, produces antioxidant effects in the prostate tissue of normal and testosterone （T）-treated rats. Methods： In our first experiment, normal rats were distributed into five groups： one group treated with the vehicle and four groups treated with D-004 （100, 200, 400 or 800 mg/kg）. In our second experiment, rats were randomized into five groups： a negative control group and four T-injected groups. The latter were comprised of a positive control group treated with the vehicle, and three groups treated with D-004 （200, 400 or 800 mg/kg）. Results： In normal rats, D-004 （100-800 mg/kg） inhibited significantly and dose-dependently iron-initiated malondialdehyde （MDA） accumulation in prostate homogenates （35.7%-80.0%） vs. the controls. D-004 （200-800 mg/kg） significantly reduced baseline MDA and carbonyl groups in prostate homogenates of normal rats to approximately 80% and 50%, respectively, and totally （100%） in T-treated rats. Conclusion： Oral treatment with D-004 reduced MDA and carbonyl groups dose-dependently and markedly in normal and T-injected rats. These findings show that D-004 given at doses effective to prevent prostate hyperplasia also produces antioxidant effects in the prostate tissue.展开更多
Despite the progress has been reached with Human herpesvirus 8 (HHV-8) research, there are gaps in the knowledge of viral induced oncogenesis. The aim of the present study was to identify possible associations between...Despite the progress has been reached with Human herpesvirus 8 (HHV-8) research, there are gaps in the knowledge of viral induced oncogenesis. The aim of the present study was to identify possible associations between HHV-8 subtypes, HHV-8 loads and clinical manifestations of HIV infected patients diagnosed with different malignancies associated with HHV-8 infection. Forty six HIV-1 infected individuals diagnosed with different HHV-8 associated diseases were studied [37 epidemic Kaposi’s sarcoma (KS), 3 pleural effusion lymphoma (PEL);5 peripheral lymphadenopathies (PL);1 Hodgkin’s lymphoma (HL);1 non Hodgkin’s lymphoma (NHL)]. HHV-8 loads were determined by quantitative real time PCR (qRT-PCR) whilst HHV-8 subtypes were determined by open-reading frame (ORF)-K1 gen genotyping. HHV-8 subtypes B, A, C, A5 and E were exhibited by 31.8%, 23.4%, 19.1%, 17% and 8.5% of the studied patients, respectively. The median HHV-8 viral load did not differ between subtypes (p > 0.05) but HHV-8 viral loads were significantly higher in PEL than in epidemic KS lesion or lymph nodes (p = 0.04). Subtype B was detected in 60% of patients with B cell lymphoma (NHL, PEL and HL) whereas subtype E was only detected in patients with epidemic KS diagnosis. Our data suggest that HHV-8 DNA quantification instead of subtype identification could be used as a surrogate marker for monitoring its infection, not only in epidemic KS patients but also in HIV infected individuals with lymphoproliferative disorders.展开更多
In this work, novel oxidative coupling complexes, [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] (n = 1 or 2, X = Cl or Br, Pip ...In this work, novel oxidative coupling complexes, [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] (n = 1 or 2, X = Cl or Br, Pip = piperidine), are synthesized from the reaction of well characterized Lewis base [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>O<sub>2</sub>] with carbon dioxide as a Lewis acid in CH<sub>2</sub>Cl<sub>2</sub>. These carbonato-derivatives are isolated as stable solids. They are easily soluble in aprotic solvents as CH<sub>2</sub>Cl<sub>2</sub>or phNO<sub>2</sub>. Cryoscopic measurements support tetranuclear structure for all of them. Electronic spectra in the near infrared with high molecular absorptivity may be explained for tetranuclear cuban structure to fulfil 3 halo-ligands for each copper centre in [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>]. The EPR spectra for [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] complexes are axial type of spectra (d<sub>x2-y2</sub> G.S) suggesting elongated tetragonal distortion for all of them. Cyclic voltammograms for [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] are irreversible in character. These tetranuclear carbonato complexes show catalytical activity. They initiate the oxidation of 2,6-dimethylphenol (DMP) to 3,3’,5,5’-tetramethyl-4,4’-diphenoquinone (DPQ).展开更多
Cuban-American relations have become one of the most attractive bilateral relations since the Cold War era.With historical methods and international relations theory,this paper aims to discuss the Cuban Revolution and...Cuban-American relations have become one of the most attractive bilateral relations since the Cold War era.With historical methods and international relations theory,this paper aims to discuss the Cuban Revolution and the change of Cuban-American relations through two issues.One is the Cuban Revolution and the gradual rupture of traditional Cuban-American ties,demonstrating that since Castro’s radical reform of nationalization deeply violated the economic interests of the United States,conflicts and confrontations had already been incurred.At the same time,with Moscow’s intervention,the Cuban Revolution gradually became complicated and sensitive to deal with from Washington’s perspective.The other one is the evolution of confrontation between the Castro revolutionary regime and the United States government during the 1959-1962 period.The Bay of Pigs Invasion rapidly caused political tensions in Cuban-American relations,and soon,the Cuban Missile Crisis institutionalized the escalating confrontation and deeply worsened bilateral relations.As a result,the Castro regime had no choice but to rely on Soviet assistance to maintain a delicate balance with the United States for several decades,which indicated the tragedy of the small nations’destiny.展开更多
Three kinds of complexes,V_2Cu_2S_4 cubane-like,VS_4Cu_4 planar and V_3S_7 triangular dusters are obtained from a reaction system composed of(NH_4)_3VS_4,CuCl,R_2dtcNa and PhSNa.A mechanism of the formation of the pro...Three kinds of complexes,V_2Cu_2S_4 cubane-like,VS_4Cu_4 planar and V_3S_7 triangular dusters are obtained from a reaction system composed of(NH_4)_3VS_4,CuCl,R_2dtcNa and PhSNa.A mechanism of the formation of the products is suggested.The title compound is structurally characterized,showing the metal oxidation states of V(IV)+Cu(I).Also discussed are IR,UV-Vis and NMR spectra,and cyclic voltagrammetry for the V_2Cu_2S_4 clusters.展开更多
文摘A new mixed-metal sulfido incomplete cubane cluster [(MoCuS3) (O) (μ-dtp) (PPh3)3] Cdtp = S2P (OC2H5)2] has been prepared by reaction of (NH4)2MoOS3 with Cu(dtp) (PPh3)2 in dimethylformamide solution. It crystallizes in the triclinic space group P1, a = 13.810(5), b = 19. 753(5), c=11. 719(4) A. α=99. 42(2), β=107. 24(3),γ=88. 05(3)°, V = 3012(2)A3, Dc = l. 51g/cm3and Z = 2. Final R=0. 046, Rw = 0. 056 for 7700 unique intensity data(I≥3σ(I)). The central unit [MoCu3S3]3+ can be described as a distorted incomplete cube with one missing corner. The Mo atom is tetrahedrally coordinated by three μ3-S atoms and one terminal O atom. Two Cu atoms are tetrahedrally coordinated whereas the third Cu atom has a highly distorted trigonal environment. The mean Mo - Cu bond length is 2. 752A. The Cu...Cu distances are in the range of 3. 200(1) -3. 740(1) A which are too long to form bonds.
基金supported by the Natural Science Foundation of Nanjing Institute of Technology (CKJA201603)the Natural Science Foundation of Jiangsu Province(BK20170761,BK20160774)+3 种基金the Jiangsu Key Laboratory Opening Project of Advanced Structural Materials and Application Technology (ASMA201707)Science Innovation Project for Undergraduates of Jiangsu Province (201811276023Z)Outstanding Scientific and Technological Innovation Team in Colleges and Universities of Jiangsu ProvinceJiangsu Overseas Visiting Scholar Program for University Prominent Young & Middle-aged Teachers and Presidents
文摘In this study,based on two attractive energetic compounds pentazole(PZ) and tetraazacubane(TAC),a new family of high energy and high nitrogen compounds pentazolyltetraazacubanes were designed.Then,a different number of NH2 or NO2 groups were introduced into the system to further adjust the property.The structures,properties,and the structure-property relationship of designed molecules were investigated theoretically.The results showed that all nine designed compounds have extremely high heat of formation(HOF,1226-2734 kJ/mol),good density(1,73-1.88 g/cm3),high detonation velocity(8.30-9.35 km/s),high detonation pressure(29.8-39.7 GPa) and acceptable sensitivity(△V:41-87 A3).These properties could be effectively positive adjusted by replacing one or two PZ rings by NH2 or/and NO2 groups,especially for the energy and sensitivity performance,which were increased and decreased obviously,respectively.As a result,two designed pentazolyltetraazacubanes were predicted to have higher energy and lower sensitivity than the famous high energy compound in use 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane,while two others have better co mbination property than 1,3,5-Trinitro-1,3,5-triazacyclohexane.In all,four new pentazolyltetraazacubanes with good combination performance were successfully designed by combining PZ with TAC,and the further property adjustment strategy of introducing a suitable amount of NH2/NO2 groups into the system.This work may help develop new cage energetic compounds.
基金Financially supported by the National Natural Science Foundation of China (No.20971063)
文摘A new Mn2Ni2 cubane complex has been synthesized and characterized by single-crystal X-ray diffraction,FT IR spectra and elemental analysis.The title compound [MnIII2NiII2（hmp）4（N3）4（O2CR）2]（hmp-is the anion of 2-pyridinemethanol and O2CR-is α-na-phthaleneacetate）crystallizes in the monoclinic system,space group P21/c with a = 10.519（5）,b = 22.109（10）,c = 23.235（9）,β = 106.096（17）o,C48H42Mn2N16Ni2O8,Mr = 1198.28,V = 5192（4）3,Dc = 1.533 g/cm3,F（000）= 2448,μ = 1.258 cm1,Z = 4,the final R = 0.0875 and wR = 0.2020 for 3398 reflections with I 2σ（I）.X-ray diffraction analysis reveals that each Mn（III）center is octahedrally coordinated by two nitrogen atoms of azide anions and three oxygen atoms from three 2-pyridinemethanol anion ligands together with one oxygen atom from naphthaleneacetate.Each Ni（II）is octahedrally coordinated by two nitrogen atoms of 2-pyridinemethanol anion ligands as well as three oxygen atoms from three 2-pyridinemethanol anion ligands and one oxygen atom from naphthaleneacetate.
基金supported by the National Natural Science Foundation of China(22171155,22071126,and 21973046)Natural Science Foundation of Shandong Province(ZR2022YQ07)+1 种基金Taishan Scholar Program(tsqn202306166)Qingdao University discipline cluster interdisciplinary joint research project(FZ2024201)。
文摘Molecular materials possessing switchable magneto-optical properties are of great interest due to their potential applications in spintronics and molecular devices.However,switching their photoluminescence(PL)and single-molecule magnet(SMM)behavior via light-induced structural changes still constitutes a formidable challenge.Here,a series of cubane structures were synthesized via self-assembly of 9-anthracene carboxylic acid(HAC)and rare-earth ions.All complexes exhibited obvious photochromic phenomena and complete PL quenching upon Xe lamp irradiation,which were realized via the synergistic effect of photogenerated radicals and[4+4]photocycloaddition of the AC components.The quenched PL showed the largest fluorescence intensity change(99.72%)in electron-transfer photochromic materials.A reversible decoloration process was realized via mechanical grinding,which is unexpectedly in the electron-transfer photochromic materials.Importantly,an SMM behavior of the Dy analog was observed after room-temperature irradiation due to the photocycloaddition of AC ligands and the photogenerated stable radicals changed the electrostatic ligand field and magnetic coupling.Moreover,based on the remarkably photochromic and photoluminescent properties of these compounds,2 demos were applied to support their application in information anti-counterfeiting and inkless printing.This work,for the first time utilizing the simultaneous modulation of photocycloaddition and photogenerated radicals in one system,realizes complete PL quenching and light-induced SMM behavior,providing a dynamical switch for the construction of multifunctional polymorphic materials with optical response and optical storage devices.
基金We acknowledge the grants from the BAGUI talent program in Guangxi Province(No.2019AC26001)the National Natural Science Foundation of China(Nos.22171075 and U23A2080).
文摘We report the stepwise in-situ manipulation of a nickel cubane nanocluster capped with a specially designed multidentate ligand [Ni^(Ⅱ)_(4)(HL)_(3)(CH_(3)O)(CH_(3)OH)_(3)](CH_(3)COO)(Ni_(4),H_(3)L=(E)-3-((2-hydroxy-3-mehoxybenzylidene)amino)propane-1,2-diol) to firstly [Ni^(Ⅱ)_(4)(HL)_(3)(CH_(3)O)(CH_(3)OH)_(2)(H_(2)O)](CH_(3)COO)(Ni4-1min) and finally to [Ni^(Ⅱ)_(4)(HL)_(3)(CH_(3)O)(H_(2)O)_(3)](CH_(3)COO)Ni4-20h)during the urea electrolysis.A combination of mass spectrometry,single crystallography and pair distribution function were employed to analyze the structural correlations of this catalyst in crystal/solution/gas phases for confirming the dynamic ligand replacement while preserving the cubic Ni4 core during catalysis.The key feature of their structures is that:(i)three ligands wrap the Ni_(4)O_(4)cubane center on one side forming the rounded outside of a calix;(ii)the opposite flat side containing labile methanol as the active site.This structure facilitates the binding of the substrate to the active central nickel atoms during catalysis.Furthermore,due to the different modes of packing,the structure of Ni4-20 h sustains two-dimensional(2D)net of open space while the structures of Ni4 and Ni4-1 min have only closed void inaccessible to solvent molecules or ions.Interestingly,the overpotential initially decreased(up to 45 min)until it is stabilized.The result showed a low potential of 1.32 V(urea oxidation reaction(UOR))at 10 mA·cm^(-2)as reflected in the Gibbs free energy decrease of~0.4 eV from Ni4 to Ni4-20 h.This work demonstrates a convincing approach for elucidating the exact nature of the active clusters in electrocatalytic process,and confirms that in-situ modification of electrode materials might alter the direct electronic interaction between substrate and active sites in improving the catalytic performance.
基金Project supported by the National Natural Science Foundation of China and the Science Foundation of Academia Sinica.
文摘Single cubane-like clusters, MFe_3S_4(R_2dtc)_5 (M=Mo, R_2=—(CH_2)_4—, Bz_2; M=W, R_2=Me_2, —(CH_2)4—; dtc=dialkyldithiocarbamate) were synthesized by assembly reaction of (NH_4)_2MS_4 (M=Mo, W), FeCl_2 with R_2dtcNa (or NH_4) in DMF. The structure, IR, EPR and cyclic voltammogram are described and discussed. MoFe_3S_4(C_4H_8dtc)_5 was also obtained from the conversion of linear cluster Fe(DMF)_6[(FeCl_2)_2MoS_4] in the presence of C_4H_8dtc NH_4. Both clusters MoFe_3S_4(C_4H_8dtc)_4·2C_2H_5CN and WFe_3S_4(C_4H_8dtc)_5·2DMF crystallize in the monoclinic space group C2/c with a=12.544(2), (Mo-cluster), 12.533(4) (W-cluster); b=20.478(4), 20.121(6); c=19.582(7), 19.659(2);β=102.82(2), 102.96(3)°; and Z=4, 4. Their structures were refined to R=0.057 and 0.064 with use of 2690 and 2179 reflections (ι>3Q(I)), respectively. Many similarities in structure for Mo and W clusters indicate that both Mo and W play a very similar role in the clusters.
基金supported by the BAGUI Talent Program in Guangxi Province(No.2019AC26001),and the National Natural Science Foundation of China(No.22171075,U23A2080).
文摘In mass spectrometry, fragments with a mass higher than the original molecular ion provide valuable insights into the molecular structure and can guide the assembly and disassembly processes for chemical synthesis. Here, we report such an example and following up by modifying the solvothermal reaction conditions (temperature and time) it is possible to isolate the high mass species in crystalline form. [Zn_(4)L_(4)Cl_(4)] (Zn_(4)L_(4), L = N-methylbenzimidazole-2-methanolate) has a boat-like Zn_(4)O_(4) core but electrospray ionization mass spectrometry (ESI-MS) of the solution of its crystals shows higher mass peaks of Zn_(5)L_(5), Zn_(5)L_(6) and Zn_(6)L_(6) species. Thus, both disassembly and reassembly are highly probable processes. Consequently, [Zn(HL)_(2)Cl_(2)] (Zn1, L = N-methylbenzimidazole-2-methanolate), [Zn_(4)L_(6)Cl_(2)] (Zn_(4)L_(6), L = N-methylbenzimidazole-2-methanolate) and [Zn_(6)L_(6)Cl_(4)(CH_(3)O)_(2)] (Zn_(6)L_(6), L = N-methylbenzimidazole-2-methanolate) were prepared. The results of multistage ESI-MS of their dissolved crystals led to a proposed mechanism of their formation in the gas phase as follows: [Zn_(3)L_(4)] through [ZnL] → [ZnL(HL)] → [Zn(HL)_(2)] → [Zn_(2)L] → [Zn_(2)L_(2)] → [Zn_(2)L_(3)]. The mechanism was derived in conjunction with Gibbs free energies calculated using DFT of the fragments observed in the ESI-MS of Zn_(4)L_(4), Zn_(4)L_(6) and Zn_(6)L_(6). This work reveals the complex of chemical reactions, involving fragmentation and unexpected combination, under mass spectrometry condition which allows one to synthesize the observed transients, leading to mechanism of formation by correlation of solid-state/solution structural information.
基金Project supported by the National Natural Science Foundation of Chinathe Science Foundation of Chinese Academy of Sciences.
文摘Three types of unit combinations, FeS2Fe + FeS2Fe, FeS2Fe + MoS2Fe and MoS2Mo + MoS2Mo, lead to Fe4S4, MoFe3S4 and Mo2Fe2S4 cubane-like clusters, respectively. A new doubly bridged single cubane cluster [Mo2Fe2S4(C4H8dtc)6]·3.5C2H2Cl4 has been obtained and its structure is discussed.
基金Project supported by 973 project （No. 2025103）, the National Natural Science Foundation of China （No. 2003028400） and the Distinguished Young Scholar Fund from the National Natural Science Foundation of China （No. 2006CB806104）.
文摘The reaction of CuI with cinchonine （an organic donor-acceptor chromophore） afforded a homochiral 3D diamondoid network [Cu4I4（cinchonine）2]n （1） containing a cubane cluster （Cu4I4） as a connecting node. This is the first homochiral coordination polymer with diamondoid nets containing a cluster as a connecting note. Its thermal stability and solid state optical properties such as fluorescence, circular dichroism and second-harmonic generation response were also reported.
文摘A novel (Me 3PhCH 2N) 2[MoFe 4S 4(SC 6H 11 ) 7] cubane like cluster was obtained from a reaction system including (NH 4) 2MoS 4, FeCl 2 and NaSC 6H 11 in methanol, and characterized by X ray crystallography. The title compound crystallizes in triclinic space group P 1 with a =1.523 1(3), b =1.610 5(3), c =1.838 3(4) nm, α =77.18 (3)°, β =75.17(3)°, γ =64.60 (3)°, and Z =2. Also included in this paper are the discussions on the variation of the reaction products obtained from the participation of cyclohexylthiolate and on the changes of the structural features of the products.
文摘The tetranuclear cubane-like complex, [NiL（EtOH）]4·0.5EtOH （1） with tridentate Schiff base ligand （H2L= 2-Hydroxymethyl-N-salicylideneaniline） has been synthesized and its crystal structure and spectroscopic properties have been studied. The complex consists of a tetranuclear （NiO）4 cubane core, of which four nickel（Ⅱ） ions are bridged by μ3-alkoxide group and each nickel（Ⅱ） ion is coordinated to three μ3-alkoxide oxygen atoms, one imino nitrogen atom and one phenoxide oxygen atom from Schiff base ligand, and further ligated by one EtOH molecule, completing a distorted octahedral geometry.
文摘On June 20,the 7th China-Latin America and Caribbean Think Tank Forum was held in Beijing.The forum carried the theme“Working Together to Build a China-LAC Community with a Shared Future.”Assistant Foreign Minister Miao Deyu attended the opening ceremony and delivered remarks.Leonel Caraballo Maqueira,Vice President of the Cuban Diplomatic Academy,and Martin Charles,Ambassador of Dominica to China and Representative of the Latin American and Caribbean Diplomatic Corps in China,attended the meeting and delivered speeches.
基金Supported by Technology Development Fund in Guangxi Academy of Agricultural Science Institute [2006008(Z)]Technology Development Fund in Guangxi Academy of Agricultural Science Institute (2005021)Special Construction Fund of Modern Agricultural Industrial Technology System (nycytx-024-01-07)~~
文摘[Objective] The artificial breeding technology of Cuban fly （Lixophaga diatraeae） and its parasitic ability on Chilo infuscatellus was studied.[Method] Through artificial inoculation experiment,the effects of different inoculation proportions between maggot and Galleria mellonella larvae on the growth and development of Cuban fly were studied.Through indoor low temperature storage tests,effects of different temperatures on the emergence rate of Cuban fly were studied;and the effects of different ecological conditions （humidity,sunshine） on the emergence rate of Cuban fly and its parasitic ability on Chilo infuscatellus were studied through indoor and field comparison experiment.[Result] The optimum inoculation proportions between maggot and G.mellonella larvae were 3：1 and 4：1,pupa production amounts were 279 and 327,respectively;short storage under the temperature of 10℃ had small effect on the emergence rate of Cuban fly,while the storage time should not exceed 15 d.Indoor and field parasitic test showed that Cuban fly had strong parasitic ability on C.infuscatellus,the parasitic rate reached 33.3%-50.0%;the parasitic rates during elongation stage and maturation stage were 47.8% and 41.7%,respectively,while they almost could not parasite during seedling stage.[Conclusion] The results provided scientific basis for artificial breeding of Cuban fly in large scale and its field release technology.
基金This work was supported by the grants from the State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter,the Chinese Academy of Sciences (CAS), the Ministry of Science and Technology of China (001CB1089), the
文摘The title compound [Er4(m3-OH)4(Hpro)4(pro)2(H2O)7](ClO4)67H2O has been synthesized and its crystal structure was determined by X-ray diffraction study. It crystallizes in rhombohedral, space group R3, a = b = c = 12.7812(2) ? a = b = g = 100.067(1), V = 1978.19(5) 3, Z = 1, Mr = 2274.77, Dc = 1.909 g/cm3, F(000) = 1112, m = 4.506mm-1, the final R = 0.0405 and wR = 0.1068 for 3711 observed reflections (I > 2s(I)). Four Er3+ ions and four m3-OH display a Er4O4 cubane structural motif. Each proline interconnects two Er3+ ions.
基金Supported by The National Centre for Scientific Research of Cuba, No. 220207
文摘AIM： To investigate the prevalence of vacuolating cytotoxin （vacA）, cytotoxin associated gene A （cagA） and blood adhesion binding antigen （babA2） genotypes of Helicobacter pylori （H pylori） isolates from Cuban dyspeptic patients. METHODS： DNA was extracted from Hpylori-positive cultures taken from 130 dyspeptic patients. Genotyping was performed by PCR, using specific primers for vacA （s1, s2, m1, m2）, cagA and babA2 genes. Endoscopic observations and histological examinations were used to determine patient pathologies. RESULTS： vacA alleles s1, s2, m1 and m2 were detected in 96 （73.8%）, 34 （26.2%）, 75 （57.7%） and 52 isolates （40%）, respectively, while the cagA gene was detected in 95 isolates （73.2%）. One hundred and seven isolates （82.3%） were babA2-positive. A significant correlation was observed between vacAs1m1 and cagA and between vacAs1ml and babA2 genotypes （P 〈 0.001 and P 〈 0.05, respectively） and between babA2 genotype and cagA status （P 〈 0.05）; but, no correlation was observed between vacAsl and babA2 genotypes. Eighty five （65.4%） and 73 （56.2%） strains were type 1 （vacAsl-cagA-positive） and ＂triplepositive＂ （vacAs1-cagA-babA2-positive）, respectively, and their presence was significantly associated with duodenal ulcer （P 〈 0.01 and P 〈 0.001, respectively）. CONCLUSION： The distribution of the main virulence factors in the Cuban strains in this study resembled that of the Western-type strains, and the more virulent H pylori isolates were significantly associated with duodenal ulcer, ulcer disease being the worst pathology observed in the group studied.
文摘Aim： To investigate whether oral treatment with D-004, a lipid extract of the Cuban royal palm fruit, produces antioxidant effects in the prostate tissue of normal and testosterone （T）-treated rats. Methods： In our first experiment, normal rats were distributed into five groups： one group treated with the vehicle and four groups treated with D-004 （100, 200, 400 or 800 mg/kg）. In our second experiment, rats were randomized into five groups： a negative control group and four T-injected groups. The latter were comprised of a positive control group treated with the vehicle, and three groups treated with D-004 （200, 400 or 800 mg/kg）. Results： In normal rats, D-004 （100-800 mg/kg） inhibited significantly and dose-dependently iron-initiated malondialdehyde （MDA） accumulation in prostate homogenates （35.7%-80.0%） vs. the controls. D-004 （200-800 mg/kg） significantly reduced baseline MDA and carbonyl groups in prostate homogenates of normal rats to approximately 80% and 50%, respectively, and totally （100%） in T-treated rats. Conclusion： Oral treatment with D-004 reduced MDA and carbonyl groups dose-dependently and markedly in normal and T-injected rats. These findings show that D-004 given at doses effective to prevent prostate hyperplasia also produces antioxidant effects in the prostate tissue.
文摘Despite the progress has been reached with Human herpesvirus 8 (HHV-8) research, there are gaps in the knowledge of viral induced oncogenesis. The aim of the present study was to identify possible associations between HHV-8 subtypes, HHV-8 loads and clinical manifestations of HIV infected patients diagnosed with different malignancies associated with HHV-8 infection. Forty six HIV-1 infected individuals diagnosed with different HHV-8 associated diseases were studied [37 epidemic Kaposi’s sarcoma (KS), 3 pleural effusion lymphoma (PEL);5 peripheral lymphadenopathies (PL);1 Hodgkin’s lymphoma (HL);1 non Hodgkin’s lymphoma (NHL)]. HHV-8 loads were determined by quantitative real time PCR (qRT-PCR) whilst HHV-8 subtypes were determined by open-reading frame (ORF)-K1 gen genotyping. HHV-8 subtypes B, A, C, A5 and E were exhibited by 31.8%, 23.4%, 19.1%, 17% and 8.5% of the studied patients, respectively. The median HHV-8 viral load did not differ between subtypes (p > 0.05) but HHV-8 viral loads were significantly higher in PEL than in epidemic KS lesion or lymph nodes (p = 0.04). Subtype B was detected in 60% of patients with B cell lymphoma (NHL, PEL and HL) whereas subtype E was only detected in patients with epidemic KS diagnosis. Our data suggest that HHV-8 DNA quantification instead of subtype identification could be used as a surrogate marker for monitoring its infection, not only in epidemic KS patients but also in HIV infected individuals with lymphoproliferative disorders.
文摘In this work, novel oxidative coupling complexes, [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] (n = 1 or 2, X = Cl or Br, Pip = piperidine), are synthesized from the reaction of well characterized Lewis base [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>O<sub>2</sub>] with carbon dioxide as a Lewis acid in CH<sub>2</sub>Cl<sub>2</sub>. These carbonato-derivatives are isolated as stable solids. They are easily soluble in aprotic solvents as CH<sub>2</sub>Cl<sub>2</sub>or phNO<sub>2</sub>. Cryoscopic measurements support tetranuclear structure for all of them. Electronic spectra in the near infrared with high molecular absorptivity may be explained for tetranuclear cuban structure to fulfil 3 halo-ligands for each copper centre in [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>]. The EPR spectra for [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] complexes are axial type of spectra (d<sub>x2-y2</sub> G.S) suggesting elongated tetragonal distortion for all of them. Cyclic voltammograms for [(Pip)<sub>4n</sub>Cu<sub>4</sub>X<sub>4</sub>(CO<sub>3</sub>)<sub>2</sub>] are irreversible in character. These tetranuclear carbonato complexes show catalytical activity. They initiate the oxidation of 2,6-dimethylphenol (DMP) to 3,3’,5,5’-tetramethyl-4,4’-diphenoquinone (DPQ).
文摘Cuban-American relations have become one of the most attractive bilateral relations since the Cold War era.With historical methods and international relations theory,this paper aims to discuss the Cuban Revolution and the change of Cuban-American relations through two issues.One is the Cuban Revolution and the gradual rupture of traditional Cuban-American ties,demonstrating that since Castro’s radical reform of nationalization deeply violated the economic interests of the United States,conflicts and confrontations had already been incurred.At the same time,with Moscow’s intervention,the Cuban Revolution gradually became complicated and sensitive to deal with from Washington’s perspective.The other one is the evolution of confrontation between the Castro revolutionary regime and the United States government during the 1959-1962 period.The Bay of Pigs Invasion rapidly caused political tensions in Cuban-American relations,and soon,the Cuban Missile Crisis institutionalized the escalating confrontation and deeply worsened bilateral relations.As a result,the Castro regime had no choice but to rely on Soviet assistance to maintain a delicate balance with the United States for several decades,which indicated the tragedy of the small nations’destiny.
基金the National Natural Science Foundation of Chinathe Climbing Program Foundation of China
文摘Three kinds of complexes,V_2Cu_2S_4 cubane-like,VS_4Cu_4 planar and V_3S_7 triangular dusters are obtained from a reaction system composed of(NH_4)_3VS_4,CuCl,R_2dtcNa and PhSNa.A mechanism of the formation of the products is suggested.The title compound is structurally characterized,showing the metal oxidation states of V(IV)+Cu(I).Also discussed are IR,UV-Vis and NMR spectra,and cyclic voltagrammetry for the V_2Cu_2S_4 clusters.
