Ethanol adsorption, decomposition and oxidation on Ir(111): a high resolution XPS study.

Ethanol (C(2)H(5)OH) adsorption, decomposition and oxidation is studied on Ir(111) using high-energy resolution, fast XPS and temperature-programmed desorption. During heating of an adsorbed ethanol layer a part of the C(2)H(5)OH(ad) desorbs molecularly, and another part remains on the surface and decomposes around 200 K; these two decomposition pathways are identified, as via acetyl (H(3)C--C=O) and via CO(ad)+CH(3ad), respectively. Acetyl and CH(3ad) decompose around 300 K into CH(ad) (and CO(ad)). CH(ad) decomposes forming C(x) and H(2) around 520 K. In the presence of O(ad) an acetate intermediate is formed around 180 K, as well as a small amount of CH(3ad) and CO(ad). Acetate decomposes between 400-480 K into CO(2), H(2)(/H(2)O) and CH(ad).     

Molecular insight into the high selectivity of double-walled carbon nanotubes

Combining experimental knowledge with molecular simulations, we investigated the adsorption and separation properties of double-walled carbon nanotubes (DWNTs) against flue/synthetic gas mixture components (e.g. CO(2), CO, N(2), H(2), O(2), and CH(4)) at 300 K. Except molecular H(2), all studied nonpolar adsorbates assemble into single-file chain structures inside DWNTs at operating pressures below 1 MPa. Molecular wires of adsorbed molecules are stabilized by the strong solid-fluid potential generated from the cylindrical carbon walls. CO(2) assembly is formed at very low operating pressures in comparison to all other studied nonpolar adsorbates. The adsorption lock-and-key mechanism results from perfect fitting of rod-shaped CO(2) molecules into the cylindrical carbon pores. The enthalpy of CO(2) adsorption in DWNTs is very high and reaches 50 kJ mol(-1) at 300 K and low pore concentrations. In contrast, adsorption enthalpy at zero coverage is significantly lower for all other studied nonpolar adsorbates, for instance: 35 kJ mol(-1) for CH(4), and 14 kJ mol(-1) for H(2). Applying the ideal adsorption solution theory, we predicted that the internal pores of DWNTs have unusual ability to differentiate CO(2) molecules from other flue/synthetic gas mixture components (e.g. CO, N(2), H(2), O(2), and CH(4)) at ambient operating conditions. Computed equilibrium selectivity for equimolar CO(2)-X binary mixtures (where X: CO, N(2), H(2), O(2), and CH(4)) is very high at low mixture pressures. With an increase in binary mixture pressure, we predicted a decrease in equilibrium separation factor because of the competitive adsorption of the X binary mixture component. We showed that at 300 K and equimolar mixture pressures up to 1 MPa, the CO(2)-X equilibrium separation factor is higher than 10 for all studied binary mixtures, indicating strong preference for CO(2) adsorption. The overall selective properties of DWNTs seem to be superior, which may be beneficial for potential industrial applications of these novel carbon nanostructures.     

A shock tube study of the CH2O + NO2 reaction at high temperatures

The reaction of CH₂O with NO₂ has been studied with a shock tube equipped with two stabilized ew CO lasers. The production of CO, NO, and H₂O has been monitored with the CO lasers in the temperature range of 1140–1650 K using three different Ar-diluted CH₂O-NO₂ mixtures. Kinetic modeling and sensitivity analysis of the observed CO, NO, and H₂O production profiles over the entire range of reaction conditions employed indicate that the bimolecular metathetical reaction, NO₂ + CH₂O → HONO + CHO (1) affects most strongly the yields of these products. Combination of the kinetically modeled values of ??₁ with those obtained recently from a low temperature pyrolytic study, ref. [8], leads to for the broad temperature range of 300–2000 K.     

Heats of formation of the propionyl ion and radical and 2,3-pentanedione by threshold photoelectron photoion coincidence spectroscopy

The dissociative photoionization onsets for the formation of the propionyl ion (C(2)H(5)CO(+)) and the acetyl ion (CH(3)CO(+)) were measured from energy selected butanone and 2,3-pentanedione ions using the technique of threshold photoelectron photoion coincidence (TPEPICO) spectroscopy. Ion time-of-flight (TOF) mass spectra recorded as a function of the ion internal energy permitted the construction of breakdown diagrams, which are the fractional abundances of ions as a function of the photon energy. The fitting of these diagrams with the statistical theory of unimolecular decay permitted the extraction of the 0 K dissociation limits of the first and second dissociation channels. This procedure was tested using the known energetics of the higher energy dissociation channel in butanone that produced the acetyl ion and the ethyl radical. By combining the measured dissociative photoionization onsets with the well-established heats of formation of CH(3)(*), CH(3)CO(+), CH(3)CO(*), and butanone, the 298 K heats of formation, Delta(f)H degrees (298K), of the propionyl ion and radical were determined to be 618.6 +/- 1.4 and -31.7 +/- 3.4 kJ/mol, respectively, and Delta(f)H degrees (298K)[2,3-pentanedione] was determined to be -343.7 +/- 2.5 kJ/mol. This is the first experimentally determined value for the heat of formation for 2,3-pentanedione. Ab initio calculations at the Weizmann-1 (W1) level of theory predict Delta(f)H degrees (298K) values for the propionyl ion and radical of 617.9 and -33.3 kJ/mol, respectively, in excellent agreement with the measured values.     

Possible existence of alkali metal orthocarbonates at high pressure

We investigate the possible existence of crystalline alkali metal orthocarbonates, A(4)CO(4), where A=Li, Na, K, Rb, and Cs. We study the equilibrium between the possible modifications of the orthocarbonate A(4)CO(4) and the binary mixture of the possible modifications of the alkali oxide A(2)O and those of the alkali metal carbonate A(2)CO(3) as function of pressure. In all cases, the orthocarbonate should be stable at sufficiently high pressure ranging from 22-32 GPa (Rb(4)CO(4)) to 200-220 GPa (Cs(4)CO(4)).     

Novel (3,4,6)-connected metal-organic framework with high stability and gas-uptake capability

A microporous and noninterpenetrated metal-organic framework [Cu(3)(L)(2)(DABCO)(H(2)O)]·15H(2)O·9DMF (1) has been synthesized using two different ligands, [1,1':3',1″-terphenyl]-4,4″,5'-tricarboxylic acid (H(3)L) and 1,4-diazabicyclo[2.2.2]octane (DABCO). As revealed by variable-temperature powder X-ray diffraction (VT-PXRD) measurements, N,N'-ditopic DABCO plays an important role for stabilization of the Cu-L framework. The three-dimensional framework of 1 exhibits high stability and excellent adsorption capacity for H(2) (54.3 mg g(-1) at 77 K and 20 bar), CO(2) (871 mg g(-1) at 298 K and 20 bar), CH(4) (116.7 mg g(-1), 99 cm(3) (STP) cm(-3) at 298 K and 20 bar), and n-pentane (686 mg g(-1) at 298 K and 1 bar). Interestingly, the excellent selectivity toward CO(2) over N(2) at ambient temperature (273 and 298 K) and 1 bar makes complex 1 possess practical application in gas separation and purification.     

A simplified and convenient laboratory-scale preparation of 14N or 15N high molecular weight poly(dichlorophosphazene) directly from PCl5

A simple and convenient one-pot synthesis of THF solutions of high molecular weight poly(dichlorophosphazene) [NPCl(2)](n), or the (15)N isotopomer [(15)NPCl(2)](n), starting directly from PCl(5) and NH(4)Cl or (15)NH(4)Cl in a solution of 1,2,4-trichlorobenzene in the presence of sulfamic acid and calcium sulfate dihydrate, is described. The solutions of [NPCl(2)](n) in THF, which are obtained free of poly(tetrahydrofuran) by preparing them in the presence of K(2)CO(3), can be reacted directly with phenols, biphenols, or even HO-CH(2)CF(3) in the presence of K(2)CO(3) or Cs(2)CO(3) to obtain, after a very simple workup, the corresponding polyphosphazene derivatives almost free of chlorine.     

Methanation of CO over nickel: Mechanism and kinetics at high H2/CO ratios

The CO methanation reaction over nickel was studied at low CO concentrations and at hydrogen pressures slightly above ambient pressure. The kinetics of this reaction is well described by a first-order expression with CO dissociation at the nickel surface as the rate-determining step. At very low CO concentrations, adsorption of CO molecules and H atoms compete for the sites at the surface, whereas the coverage of CO is close to unity at higher CO pressures. The ratio of the equilibrium constants for CO and H atom adsorption, K(CO)/K(H), was obtained from the rate of CO methanation at various CO concentrations. K(H) was determined independently from temperature programmed adsorption/desorption of hydrogen to be K(H) = 7.7 x 10(-4) (bar(-0.5)) exp[43 (kJ/mol)/RT] and hence the equilibrium constants for adsorption of CO molecules may be calculated to be K(CO) = 3 x 10(-7) (bar(-1)) exp[122 (kJ/mol)/RT]. Furthermore, the rate of dissociation of CO at the catalyst surface was determined to be 5 x 10(9) (s(-1)) exp[-96.7 (kJ/mol)/RT] assuming that 5% of the surface nickel atoms are active for CO dissociation. The results are compared to equilibrium and rate constants reported in the literature.     

Enhancement of CO2 sorption uptake on hydrotalcite by impregnation with K2CO3

The awareness of symptoms of global warming and its seriousness urges the development of technologies to reduce greenhouse gas emissions. Carbon dioxide (CO(2)) is a representative greenhouse gas, and numerous methods to capture and storage CO(2) have been considered. Recently, the technology to remove high-temperature CO(2) by sorption has received lots of attention. In this study, hydrotalcite, which has been known to have CO(2) sorption capability at high temperature, was impregnated with K(2)CO(3) to enhance CO(2) sorption uptake, and the mechanism of CO(2) sorption enhancement on K(2)CO(3)-promoted hydrotalcite was investigated. Thermogravimetric analysis was used to measure equilibrium CO(2) sorption uptake and to estimate CO(2) sorption kinetics. The analyses based on N(2) gas physisorption, X-ray diffractometry, Fourier transform infrared spectrometry, Raman spectrometry, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were carried out to elucidate the characteristics of sorbents and the mechanism of enhanced CO(2) sorption. The equilibrium CO(2) sorption uptake on hydrotalcite could be increased up to 10 times by impregnation with K(2)CO(3), and there was an optimal amount of K(2)CO(3) for a maximum equilibrium CO(2) sorption uptake. In the K(2)CO(3)-promoted hydrotalcite, K(2)CO(3) was incorporated without changing the structure of hydrotalcite and it was thermally stabilized, resulting in the enhanced equilibrium CO(2) sorption uptake and fast CO(2) sorption kinetics.     

五元交互体系Li+,Na+,K+//CO32-,Cl--H2O在298.15K的相平衡研究

针对西藏扎布耶盐湖卤水组成,采用等温溶解平衡法研究了五元交互体系Li+,Na+,K+//CO32-,Cl--H2O于298.15K时的相平衡,并绘制了相图(空间立体图和Li2CO3饱和的投影图).结果表明,该五元体系相图含有7个结晶区、13条单变量线和4个无变量点.7个结晶区由6个单盐结晶区和1个复盐结晶区组成,分别为LiCl·H2O,NaCl,KCl,Li2CO3,K2CO3·3/2H2O,Na2CO3·10H2O和NaKCO3·6H2O,没有形成固溶体和天然碱(Na2CO3·NaHCO3·2H2O).4个无变量点标记成K1,K2,K3和K4,所对应的平衡固相盐分别是:Li2CO3+NaKCO3·6H2O+Na2CO3·10H2O+KCl,Li2CO3+NaKCO3·6H2O+K2CO3·3/2H2O+KCl,Li2CO3+NaCl+KCl+LiCl·H2O和Li2CO3+NaCl+Na2CO3·10H2O+KCl.     

Syntheses and reactivities of disubstituted and trisubstituted fluorous pyridines with high fluorous phase affinities: solid state,liquid crystal,and ionic liquid-phase properties

Reactions of 2,6-dibromo-, 3,5-dibromo-, and 2,4,6-tribromopyridine with IZnCH(2)CH(2)R(f8) (R(f8) = (CF(2))(7)CF(3)) in THF at 65 degrees C in the presence of trans-Cl(2)Pd(PPh(3))(2) (5 mol %) gave the fluorous pyridines 2,6- and 3,5-NC(5)H(3)(CH(2)CH(2)R(f8))(2) (1 and 2; 85%, 31%) and 2,4,6-NC(5)H(2)(CH(2)CH(2)R(f8))(3) (3, 61%). Reaction of 2,6-pyridinedicarboxaldehyde with [Ph(3)PCH(2)CH(2)R(f8)](+)I(-)/K(2)CO(3) (p-dioxane/H(2)O, 95 degrees C) gave 2,6-NC(5)H(3)(CH[double bond]CHCH(2)R(f8))(2) (95%; 70:30 ZZ/ZE), which was treated with H(2) (1 atm, 12 h) and 10% Pd/C to yield 2,6-NC(5)H(3)(CH(2)CH(2)CH(2)R(f8))(2) (5, 95%), a higher homologue of 1. Longer reaction times afforded piperidine cis-2,6-HNC(5)H(8)(CH(2)CH(2)CH(2)R(f8))(2) (6, 98%). The stereochemistry was established by NMR analysis of the N-benzylpiperidine. Pyridines 1-3 and 5 are low-melting white solids with CF(3)C(6)F(11)/toluene partition coefficients (24 degrees C) of 93.8:6.2, 93.9:6.1, >99.7:<0.3, and 90.4:9.6, respectively (6, 93.6:6.4). Reaction of 1 and CF(3)SO(3)H gave a pyridinium salt, and Cl(2)Pd(NCCH(3))(2) (0.5 equiv) yielded trans-Cl(2)Pd(1)(2). The crystal structure of the former, which also exhibited liquid crystalline and ionic liquid phases, was determined.     

A photoelectron and TPEPICO investigation of the acetone radical cation

The valence shell photoelectron spectrum, threshold photoelectron spectrum, and threshold photoelectron photoion coincidence (TPEPICO) mass spectra of acetone have been measured using synchrotron radiation. New vibrational progressions have been observed and assigned in the X 2B2 state photoelectron bands of acetone-h6 and acetone-d6, and the influence of resonant autoionization on the threshold electron yield has been investigated. The dissociation thresholds for fragment ions up to 31 eV have been measured and compared to previous values. In addition, kinetic modeling of the threshold region for CH3* and CH4 loss leads to new values of 78 +/- 2 kJ mol(-1) and 75 +/- 2 kJ mol(-1), respectively, for the 0 K activation energies for these two processes. The result for the methyl loss channel is in reasonable agreement with, but slightly lower than, that of 83 +/- 1 kJ mol(-1) derived in a recent TPEPICO study by Fogleman et al. The modeling accounts for both low-energy dissociation channels at two different ion residence times in the mass spectrometer. Moreover, the effects of the ro-vibrational population distribution, the electron transmission efficiency, and the monochromator band-pass are included. The present activation energies yield a Delta(f)H298 for CH3CO+ of 655 +/- 3 kJ mol(-1), which is 4 kJ mol(-1) lower than that reported by Fogleman et al. The present Delta(f)H298 for CH3CO+ can be combined with the Delta(f)H298 for CH2CO (-47.5 +/- 1.6 kJ mol(-1)) and H+ (1530 kJ mol(-1)) to yield a 298 K proton affinity for ketene of 828 +/- 4 kJ mol(-1), in good agreement with the value (825 kJ mol(-1)) calculated at the G2 level of theory. The measured activation energy for CH4 loss leads to a Delta(f)H298 (CH2CO+*) of 873 +/- 3 kJ mol(-1).     

Optical absorption and photoluminescence properties of Er3+ doped mixed alkali borate glasses

An investigations of the optical absorption and fluorescence spectra of 0.2 mol% Er2O3 in mixed alkali borate glasses of the type 67.8B2O3 x xLi2O(32-x)Na2O, 67.8B2O3 x xLi2O(32-x)K2O and 67.8B2O3 x xNa2O(32-x)K2O (where x = 8, 12, 16, 20 and 24) are presented. The glasses were obtained by quenching melts consisting of H3BO3, Li2CO3, Na2CO3, K2CO3 and Er2O3 (950-1100 degrees C, 1.5-2 h) between two brass plates. Spectroscopic parameters like Racah (E1, E2 and E3), spin-orbit (xi(4f)) and configuration interaction (alpha) parameters are deduced as function of x. Using Judd-Ofelt theory, Judd-Ofelt intensity parameters (omega2, omega4 and omega6) are obtained. Radiative and non-radiative transition rates (A(T) and W(MPR)), radiative lifetimes (tauR), branching ratios (beta) and integrated absorption cross-sections (sigma) have been computed for certain excited states of Er3+ in these mixed alkali borate glasses. Emission spectra have been studied for all the three Er3+ doped mixed alkali borate glasses. The present paper throws light on the trends observed in the intensity parameters, radiative lifetimes, branching ratios and emission cross-sections as a function of x in these borate glasses, keeping in view the effect of mixed alkalies in borate glasses.     

Isolation of (CO)1- and (CO2)1- radical complexes of rare earths via Ln(NR2)3/K reduction and [K2(18-crown-6)2]2+ oligomerization

Deep-blue solutions of Y(2+) formed from Y(NR(2))(3) (R = SiMe(3)) and excess potassium in the presence of 18-crown-6 at -45 °C under vacuum in diethyl ether react with CO at -78 °C to form colorless crystals of the (CO)(1-) radical complex, {[(R(2)N)(3)Y(μ-CO)(2)][K(2)(18-crown-6)(2)]}(n), 1. The polymeric structure contains trigonal bipyramidal [(R(2)N)(3)Y(μ-CO)(2)](2-) units with axial (CO)(1-) ligands linked by [K(2)(18-crown-6)(2)](2+) dications. Byproducts such as the ynediolate, [(R(2)N)(3)Y](2)(μ-OC≡CO){[K(18-crown-6)](2)(18-crown-6)}, 2, in which two (CO)(1-) anions are coupled to form (OC≡CO)(2-), and the insertion/rearrangement product, {(R(2)N)(2)Y[OC(═CH(2))Si(Me(2))NSiMe(3)]}[K(18-crown-6)], 3, are common in these reactions that give variable results depending on the specific reaction conditions. The CO reduction in the presence of THF forms a solvated variant of 2, the ynediolate [(R(2)N)(3)Y](2)(μ-OC≡CO)[K(18-crown-6)(THF)(2)](2), 2a. CO(2) reacts analogously with Y(2+) to form the (CO(2))(1-) radical complex, {[(R(2)N)(3)Y(μ-CO(2))(2)][K(2)(18-crown-6)(2)]}(n), 4, that has a structure similar to that of 1. Analogous (CO)(1-) and (OC≡CO)(2-) complexes of lutetium were isolated using Lu(NR(2))(3)/K/18-crown-6: {[(R(2)N)(3)Lu(μ-CO)(2)][K(2)(18-crown-6)(2)]}(n), 5, [(R(2)N)(3)Lu](2)(μ-OC≡CO){[K(18-crown-6)](2)(18-crown-6)}, 6, and [(R(2)N)(3)Lu](2)(μ-OC≡CO)[K(18-crown-6)(Et(2)O)(2)](2), 6a.     

The tunnel of acetyl-coenzyme a synthase/carbon monoxide dehydrogenase regulates delivery of CO to the active site

The effect of [CO] on acetyl-CoA synthesis activity of the isolated alpha subunit of acetyl-coenzyme A synthase/carbon monoxide dehydrogenase from Moorella thermoacetica was determined. In contrast to the complete alpha(2)beta(2) enzyme where multiple CO molecules exhibit strong cooperative inhibition, alpha was weakly inhibited, apparently by a single CO with K(I) = 1.5 +/- 0.5 mM; other parameters include k(cat) = 11 +/- 1 min(-)(1) and K(M) = 30 +/- 10 microM. The alpha subunit lacked the previously described "majority" activity of the complete enzyme but possessed its "residual" activity. The site affording cooperative inhibition may be absent or inoperative in isolated alpha subunits. Ni-activated alpha rapidly and reversibly accepted a methyl group from CH(3)-Co(3+)FeSP affording the equilibrium constant K(MT) = 10 +/- 4, demonstrating the superior nucleophilicity of alpha(red) relative to Co(1+)FeSP. CO inhibited this reaction weakly (K(I) = 540 +/- 190 microM). NiFeC EPR intensity of alpha developed in accordance with an apparent K(d) = 30 microM, suggesting that the state exhibiting this signal is not responsible for inhibiting catalysis or methyl group transfer and that it may be a catalytic intermediate. At higher [CO], signal intensity declined slightly. Attenuation of catalysis, methyl group transfer, and the NiFeC signal might reflect the same weak CO binding process. Three mutant alpha(2)beta(2) proteins designed to block the tunnel between the A- and C-clusters exhibited little/no activity with CO(2) as a substrate and no evidence of cooperative CO inhibition. This suggests that the tunnel was blocked by these mutations and that cooperative CO inhibition is related to tunnel operation. Numerous CO molecules might bind cooperatively to some region associated with the tunnel and institute a conformational change that abolishes the majority activity. Alternatively, crowding of CO in the tunnel may control flow through the tunnel and deliver CO to the A-cluster at the appropriate step of catalysis. Residual activity may involve CO from the solvent binding directly to the A-cluster.     

Water-assisted interconversions and dissociations of the acetaldehyde ion and its isomers. An experimental and theoretical study

The gas-phase reactions of the ion [CH(3)CHO/H(2)O](+*) have been investigated by mass spectrometry. The metastable ion (MI) mass spectrum reveals that this ion-molecule complex decomposes spontaneously by the losses of H(2)O, CO, and (*)CH(3). The structures of stable complexes and transition states involved in the potential energy surface (PES) have been studied by the G3//B3-LYP/6-31+G(d) computational method. Hydrogen-bridged water complexes have been found to be the major products of the losses of CO and (*)CH(3). The CO loss produces the [(*)CH(3)...H(3)O(+)] ion and involves a "backside displacement" mechanism. The products corresponding to (*)CH(3) loss have been assigned by theory to be [OC...H(3)O(+)] and [CO...H(3)O(+)], and their 298 K enthalpy values, calculated at the G3 level of theory, are Delta(f)H[OC...H(3)O(+)] = 420 kJ/mol and Delta(f)H[CO...H(3)O(+)] = 448 kJ/mol. The PES describing the interconversions among water-solvated CH(3)CHO(+*), CH(3)COH(+*), and CH(2)CHOH(+*) have been shown to involve proton-transport catalysis (PTC), catalyzed 1,2 H-transfer, and an uncatalyzed H-atom transfer mechanism, respectively.     

钾负载量对CuO/K_2CO_3/MgAl_2O_4催化剂高温NO_x储存还原性能的影响

制备了适用于高温氮氧化物储存还原(NSR)反应的Cu O/K_2CO_3/MgAl_2O_4非贵金属催化剂,考察了钾负载量对催化剂NSR性能的影响,发现钾主要以高分散K_2CO_3和体相K_2CO_3的形式存在.在稀燃条件下,NOx在体相K_2CO_3上形成了高温稳定的硝酸盐物种,而高分散K_2CO_3上形成的硝酸盐的高温稳定性则较差.当钾负载量较低时,催化剂的NOx储存能力有限,K_2CO_3主要以高分散形式存在,稀燃阶段形成的硝酸盐的热稳定性较低,高温NSR活性较低;而钾负载量过高时,K_2CO_3则会覆盖Cu O活性位,从而降低催化剂的NSR活性.在450℃的高温条件下,钾负载量为10%时,所制备催化剂的NOx储存还原能力最佳,NOx还原效率达到99.9%,是一种具有潜在应用前景的高温NSR催化剂.     

Pt羰基簇合物在NaY内的合成机理

利用IR，EXAFS, ~(13)CO同位素交换反应及与NO作用等手段研究了Pt羰基簇合物[Pt_3(CO)_6]~(2-)_n(n＝3,4)在NaY分子筛超笼内的合成机理．在氧化样品Pt~(2+)/NaY上300－373 K的还愿羰基化过程中，首先Pt~(2+)与CO反应生成PtO(CO)物种(波数σ_(CO)＝2110 cm~(-1))，然后聚集成“Pt_3(CO)_6”(σ_(CO)＝2112，1896和1841 cm~(-1))，最后生成深绿色的Pt羰基簇合物Pt_(12)(CO)_(24)]~(2-)/NaY(σ_(CO)＝2080，1824 cm~(-1))．“Pt_3(CO)_6”的羰基在室温下能迅速地与~(13)CO发生交换，而[Pt_3(CO)_6]~(2-)_n(n＝3,4)的羰基与~(13)CO的同位素交换即使在343 K也进行得很慢，室温下，NO能逐步破坏Pt羰基簇合物的层间和层内Pt－Pt键，得到中间物种“Pt_3(CO)_6”和PtO(CO)，同时在气相产生CO_2和N_2O．而由上述两中间物种出发，300－353 K温度下，在CO气氛中的还原羰基化又能可逆地得到原羰基簇合物．     

Rheology,electrical conductivity,and the phase behavior of cocontinuous PA6/ABS blends with MWNT: Correlating the aspect ratio of MWNT with the percolation threshold

Multiwalled carbon nanotubes (purified, p‐MWNT and ～ NH₂ functionalized, f‐MWNT) were melt‐mixed with 50/50 cocontinuous blends of polyamide 6 (PA6) and acrylonitrile–butadiene–styrene in a conical twin‐screw microcompounder to obtain conductive polymer blends utilizing the conceptual approach of double‐percolation. The state of dispersion of the tubes was assessed using AC electrical conductivity measurements and melt‐rheology. The rheological and the electrical percolation threshold was observed to be ～ 1–2 wt % and ～ 3–4 wt %, respectively, for blends with p‐MWNT. In case of blends with f‐MWNT, the rheological percolation threshold was observed to be higher (2–3 wt %) than p‐MWNT but the electrical percolation threshold remained almost same. However, the absolute values were significantly lower than blends with p‐MWNT. In addition, significant refinement in the cocontinuous morphology of the blends with increasing concentration of MWNT was observed in both the cases. Further, an attempt was made to understand the underlying concepts in relation to cocontinuous morphologies that how the geometrical percolation threshold which adversely suffered because of the attrition of tubes under prolonged shear contributed further in retaining the rheological percolation threshold. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1619–1631, 2008     

Single-walled polytetrazolate metal-organic channels with high density of open nitrogen-donor sites and gas uptake

The self-assembly between zinc dimer and 1,3,5-tris(2H-tetrazol-5-yl)benzene (H(3)BTT), promoted by a urea derivative, leads to a highly porous 3D framework with a large percentage (67%) of N-donor sites unused for bonding with metals. The material exhibits high gas storage capacity (ca. 1.89 wt % H(2) at 77 K and 1 atm; 98 cm(3)/g CO(2) at 273 K and 1 atm), even in the absence of open metal sites. The high percentage of open N-donor sites, coupled with the low framework density resulting from single-walled channels, is believed to contribute to the high uptake capacity.