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1.
A triphosphaazatriangulene (H3L) was synthesized through an intramolecular triple phospha-Friedel–Crafts reaction. The H3L triangulene contains three phosphinate groups and an extended π-conjugated framework, which enables the stimuli-responsive reversible transformation of [Cu(HL)(DMSO)⋅(MeOH)]n, a 3D-MOF that exhibits reversible sorption characteristics, into (H3L⋅0.5 [Cu2(OH)4⋅6 H2O] ⋅4 H2O), a 1D-columnar assembled proton-conducting material. The hydrophilic nature of the latter resulted in a proton conductivity of 5.5×10−3 S cm−1 at 95 % relative humidity and 60 °C.  相似文献   

2.
Anhydrous silicophosphoric acid glass with an approximate composition of H5Si2P9O29 was synthesized and its thermal and proton-conducting properties were characterized. Despite exhibiting a glass transition at 192 °C, the supercooled liquid could be handled as a solid up to 280 °C owing to its high viscosity. The glass and its melt exhibited proton conduction with a proton transport number of ∼1. Although covalent O−H bonds were weakened by relatively strong hydrogen bonding, the proton conductivity (4×10−4 S cm−1 at 276 °C) was considerably lower than that of phosphoric acid. The high viscosity of the melt was due to the tight cross-linking of phosphate ion chains by six-fold-coordinated Si atoms. The low proton conductivity was attributed to the trapping of positively charged proton carriers around anionic SiO6 units (expressed as (SiO6/2)2−) to compensate for the negative charges.  相似文献   

3.
Phosphate-based silver–bipyridine (Ag-bpy) 1D coordination polymer {[{Ag(4,4′-bpy)}2{Ag(4,4′-bpy)(H2PO4)}] ⋅ 2 H2PO4 ⋅ H3PO4 ⋅ 5 H2O}n ( 1 ) with free phosphoric acid (H3PO4), its conjugate base (H2PO4) and water molecules in its lattice was synthesized by room-temperature crystallization and the hydrothermal method. An XRD study showed that coordinated H2PO4, lattice H2PO4 anions, free H3PO4 and lattice water molecules are interconnected by H-bonding interactions, forming an infinitely extended 2D H-bonded network that facilitates proton transfer. This material exhibits a high proton conductivity of 3.3×10−3 S cm−1 at 80 °C and 95 % relative humidity (RH). Furthermore, synthesis of this material from commercially available starting materials in water can be easily scaled up, and it is highly stable under extreme conditions of conductivity measurements. This report inaugurates the usage and design principle of proton-conducting frameworks based on crystallized phosphoric acid and phosphate.  相似文献   

4.
The deactivation of I(2P½) by R-OH compounds (R = H, CnH2n+1) was studied using time-resolved atomic absorption at 206.2 nm. The second-order quenching rate constants determined for H2O, CH3OH, C2H5OH, n-C3H7OH, i-C3H7OH, n-C4H9OH, i-C4H9OH, s-C4H9OH, t-C4H9OH, are respectively, 2.4 ± 0.3 × 10−12, 5.5 ± 0.8 × 10−12, 8 ± 1 × 10−12, 10 ± 1 × 10−12, 10 ± 1 × 10−12, 11.1 ± 0.9 × 10−12, 9.8 ± 0.9 × 10−12, 7.1 ± 0.7 × 10−12, and 4.1 ± 0.4× 10−12 cm3 molec−1 s−1 at room temperature. It is believed that a quasi-resonant electronic to vibrational energy transfer mechanism accounts for most of the features of the quenching process. The influence of the alkyl group and its role in the total quenching rate is also discussed. © 1997 John Wiley & Sons, Inc.  相似文献   

5.
The kinetics and mechanisms of the reactions of aluminium(III) with pentane-2,4-dione (Hpd), 1,1,1-trifluoro pentane-2,4-dione (Htfpd) and heptane-3,5-dione (Hhptd) have been investigated in aqueous solution at 25°C and ionic strength 0.5 mol dm−3 sodium perchlorate. The kinetic data are consistent with a mechanism in which aluminium(III) reacts with the β-diketones by two pathways, one of which is acid independent while the second exhibits a second-order inverse-acid dependence. The acid-independent pathway is ascribed to a mechanism in which [Al(H2O)6]3+ reacts with the enol tautomers of Hpd, Htfpd, and Hhptd with rate constants of 1.7(±1.3)×10−2, 0.79(±0.21), and 7.5(±1.6)×10−3 dm3 mol−1 s−1, respectively. The inverse acid pathway is consistent with a mechanism in which [Al(H2O)5(OH)]2+ reacts with the enolate ions of Hpd, Htfpd, and Hhptd with rate constants of 4.32(±0.18)×106, 5.84(±0.24)×103, and 1.67(±0.05)×107 dm3 mol−1 s−1, respectively. An alternative formulation involves a pathway in which [Al(H2O)4(OH)2]+ reacts with the protonated enol tautomers of the ligands. This gives rate constants of 2.79(±0.12)×104, 3.86(±0.16)×105, and 8.98(±0.25)×103 dm3 mol−1 s−1 for reaction with Hpd, Htfpd, and Hhptd, respectively. Consideration of the kinetic data reported here together with data from the literature, suggest that [Al(H2O)5(OH)]2+ reacts by an associative or associative-interchange mechanism. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 257–266, 1998.  相似文献   

6.
Two new complexes based on 4,4′-[1,3-phenylenebis(oxy)]diphthalic acid (H4L) ligands were synthesized, namely, [Cd2(L)(1,10-phen)2(H2O)]n( 1 ) and [Co2(L)(1,10-phen)2(H2O)]n( 2 ), in which 2D structures transform into 3D supramolecular structures by C H···π interaction. The proton conductivity of complexes 1 and 2 at low temperature is close (σ1 = 3.12 × 10−8 S cm−1 and σ2 = 3.81 × 10−8 S cm−1 at 30°C), but these two complexes show different conduction mechanisms. The Vehicular mechanism in 1 is caused by the O···H/H···O contact in 1 , which is stronger than 2 , and the Grotthuss mechanism in 2 is caused by the N···H/H···N contact in 2 , which is stronger than 1 . At the same time, complex 1 showed excellent antibacterial properties in vitro, mainly reflected in that five kinds of bacteria (Escherichia coli, Bacillus amyloliquefaciens, Pantoea agglomerans, Pseudomonas putida, and Pectobacterium carotovora) could play an obvious inhibitory effect in the concentration range of 20 μg·ml−1.  相似文献   

7.
A detailed study was performed of the interrelationships of the lattice parameters, ionic conductivity, and infrared spectrum of HTi2NbO7 · 2H2O as a function of dehydration. We have shown that the oxide layers in this ion-exchange compound are interespaced with water layers 2-molecules thick, providing a rare example of a bilayer hydrate. Bulk proton transport occurs through these layers, with a conductivity of (8 ± 4) × 10?6 ohm?1cm?1 at 20°C. Upon heating to 55°C, 0.5 H2O per formula was gradually lost, but the conductivity was essentially retained. Upon further heating to 62°C another 0.5 H2O was rapidly lost, resulting in a conductivity drop of a factor of 10. Further water was gradually lost until HTi2NbO7 was reached at 220°C. The X-ray evidence revealed no discrete, fixed-composition hydrate phases, indicating a single isostructural phase from HTi2NbO7 · 2H2O to HTi2NbO7, with a single continuously variable interlayer spacing. The bulk conductivity of CsTi2NbO7 was less than 10?8 ohm?1cm?1.  相似文献   

8.
The Mx Hy (A O4)z acid salts (M = Cs, Rb, K, Na, Li, NH4; A = S, Se, As, P) exhibit ferroelectric properties. The solid acids have low conductivity values and are of interest with regard to their thermal properties and proton conductivity. The crystal structure of caesium dihydrogen orthophosphate monohydrogen orthophosphate dihydrate, Cs3(H1.5PO4)2·2H2O, has been solved. The compound crystallizes in the space group Pbca and forms a structure with strong hydrogen bonds connecting phosphate tetrahedra that agrees well with the IR spectra. The dehydration of Cs3(H1.5PO4)2·2H2O with the loss of two water molecules occurs at 348–433 K. Anhydrous Cs3(H1.5PO4)2 is stable up to 548 K and is then converted completely into caesium pyrophosphate (Cs4P2O7) and CsPO3. Anhydrous Cs3(H1.5PO4)2 crystallizes in the monoclinic C 2 space group, with the unit‐cell parameters a = 11.1693 (4), b = 6.4682 (2), c = 7.7442 (3) Å and β = 71.822 (2)°. The conductivities of both compounds have been measured. In contrast to crystal hydrate Cs3(H1.5PO4)2·2H2O, the dehydrated form has rather low conductivity values of ∼6 × 10−6–10−8 S cm−1 at 373–493 K, with an activation energy of 0.91 eV.  相似文献   

9.
A multi-responsive Cd metal–organic framework {[Cd (ttpe)(H2O)(ip)]•4H2O•DMAC}n ( 1•4H 2 O•DMAC ) was synthesized using hydrothermal method (ttpe = 1,1,2,2-tetra(4-(1H-1,2,4-triazol-1-yl)phenyl)ethylene, ip = isophthalate, DMAC = N,N-dimethylacetamide), and characterized. 1 exhibits a 2D (4,4) network. The luminescent sensing experimrnts showed that 1•4H 2 O•DMAC as a new MOF luminescent sensor can detect Cr2O72−, CrO42−, MnO4, Cu2+, Ag+ and Fe3+ in aqueous solution with simultaneously high efficiency and high sensitivity. The quenching constants Ksv for Cr2O72−, CrO42−, MnO4, Cu2+, Ag+ and Fe3+ are 4.231 × 104 M−1, 2.471 × 104 M−1, 6.459 × 103 M−1, 7.617 × 103 M−1, 1.563 × 104 M−1 and 3.574 × 104 M−1, respectively. The detection limits are 0.094 μM for Cr2O72−, 0.108 μM for CrO42 − , 0.346 μM for MnO4, 0.302 μM for Cu2+, 0.221 μM for Ag + , and 0.100 μM for Fe3+. 1•4H 2 O•DMAC exhibits high photocatalytic efficiency for degradation of methylene blue under visible light irradiation.  相似文献   

10.
The rate constants of the reactions of ethoxy (C2H5O), i‐propoxy (i‐C3H7O) and n‐propoxy (n‐C3H7O) radicals with O2 and NO have been measured as a function of temperature. Radicals have been generated by laser photolysis from the appropriate alkyl nitrite and have been detected by laser‐induced fluorescence. The following Arrhenius expressions have been determined: (R1) C2H5O + O2 → products k1 = (2.4 ± 0.9) × 10−14 exp(−2.7 ± 1.0 kJmol−1/RT) cm3 s−1 295K < T < 354K p = 100 Torr (R2) i‐C3H7O + O2 → products k2 = (1.6 ± 0.2) × 10−14 exp(−2.2 ± 0.2 kJmol−1/RT) cm3 s−1 288K < T < 364K p = 50–200 Torr (R3) n‐C3H7O + O2 → products k3 = (2.5 ± 0.5) × 10−14 exp(−2.0 ± 0.5 kJmol−1/RT) cm3 s−1 289K < T < 381K p = 30–100 Torr (R4) C2H5O + NO → products k4 = (2.0 ± 0.7) × 10−11 exp(0.6 ± 0.4 kJmol−1/RT) cm3 s−1 286K < T < 388K p = 30–500 Torr (R5) i‐C3H7O + NO → products k5 = (8.9 ± 0.2) × 10−12 exp(3.3 ± 0.5 kJmol−1/RT) cm3 s−1 286K < T < 389K p = 30–500 Torr (R6) n‐C3H7O + NO → products k6 = (1.2 ± 0.2) × 10−11 exp(2.9 ± 0.4 kJmol−1/RT) cm3s−1 289K < T < 380K p = 30–100 Torr All reactions have been found independent of total pressure between 30 and 500 Torr within the experimental error. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 860–866, 1999  相似文献   

11.
A novel metal–organic framework [Zn3(Ni-H2TPPP)(Ni-H4TPPP)(Ni-H5TPPP) ⋅ 7(CH3)2NH2 ⋅ DMF ⋅ 7 H2O] (where Ni-HxTPPP (x=2,4,5) are partially deprotonated [5,10,15,20-tetrakis(3-(phosphonatophenyl)-porphyrinato(2-))]nickel(II) species), IPCE-2Ni , with outstanding proton conductivity (1.0×10−2 S cm−1 at 75 °C and 95 % relative humidity) has been obtained. The high concentration of free phosphonate groups and compensating dimethylammonium cations bound by hydrogen bonds in the unique crystal structure of IPCE-2Ni is a key factor responsible for the observed high proton conductivity, which is one order of magnitude higher than for the corresponding MOF based on 5,10,15,20-tetrakis(4-(phosphonatophenyl)porphyrinato(2-))]nickel(II) IPCE-1Ni and comparable with that of leaders among MOFs.  相似文献   

12.
Perovskite phases Ba3In2ZrO8 and Ba4In2Zr2O11 with the nominal concentration of structural oxygen vacancies 1/9 and 1/12, respectively, were synthesized by solid-phase and solution methods. X-ray diffraction showed cubic symmetry of both phases with the unit cell parameter a = 0.4193(2) and 0.4204(3) nm, respectively. The absence of superstructural lines resulted in the conclusion on statistical arrangement of oxygen vacancies. Thermogravimetry and mass spectrometry proved that both phases can reversibly absorb water from gas phase (pH2O = 2 × 10−2 atm) with observed correlation between the concentration of oxygen vacancies and amount of absorbed water. The total water amount was up to 0.9 mol per formula unit or, if recalculated for perovskite unit ABO3, 0.3 and 0.23 mol H2O, respectively. The temperature curves of coductivity in the atmosphere with various partial water vapor pressures (pH2O = 3 × 10−5 and 2 × 10−2 atm) showed significantly higher conductivity and lower activation energy (0.52 eV) in humid atmosphere due to proton transfer. The proton conductivity is up to 5 × 10−4 Ohm−1 cm−1 at 300°C for Ba3In2ZrO8 specimen. IR spectrometry showed that protons in the structure exist primarily in OH-groups.  相似文献   

13.
The rate coefficient for the reaction of the peroxypropionyl radical (C2H5C(O)O2) with NO was measured with a laminar flow reactor over the temperature range 226–406 K. The C2H5C(O)O2 reactant was monitored with chemical ionization mass spectrometry. The measured rate coefficients are k(T) = (6.7 ± 1.7) × 10−12 exp{(340 ± 80)/T} cm3 molecule−1 s−1 and k(298 K) = (2.1 ± 0.2) × 10−11 cm3 molecule−1 s−1. Our results are comparable to recommended rate coefficients for the analogous CH3C(O)O2 + NO reaction. Heterogeneous effects, pressure dependence, and concentration gradients inside the flow reactor are examined. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet: 31: 221–228, 1999  相似文献   

14.
Developing a robust metal-organic framework (MOF) which facilitates proton hopping along the pore channels is very demanding in the context of fabricating an efficient proton-conducting membrane for fuel cells. Herein, we report the synthesis of a novel tetradentate aromatic phosphonate ligand H8L (L=tetraphenylethylene tetraphosphonic acid) based Ni-MOF, whose crystal structure has been solved from single-crystal X-ray diffraction. Ni-MOF [Ni2(H4L)(H2O)9(C2H7SO)(C2H7NCO)] displays a monoclinic crystal structure with a space group of P 21/c, a=11.887 Å, b=34.148 Å, c=11.131 Å, α= γ =90°, β=103.374°, where a nickel-hexahydrate moiety located inside the void space of the framework through several H-bonding interactions. Upon treatment of the Ni-MOF in different pH media as well as solvents, the framework remained unaltered, suggesting the presence of strong H-bonding interactions in the framework. High framework stability of Ni-MOF bearing H-bonding interactions motivated us to explore this metal-organic framework material as proton-conducting medium after external proton doping. Due to the presence of a large number of H-bonding interactions and the presence of water molecules in the framework we have carried out the doping of organic p-toluenesulfonic acid (PTSA) and inorganic sulphuric acid (SA) in this Ni-MOF and observed high proton conductivity of 5.28×10−2 S cm−1 at 90 °C and 98% relative humidity for the SA-doped material. Enhancement of proton conductivity by proton doping under humid conditions suggested a very promising feature of this Ni-MOF.  相似文献   

15.
When complexed with alkaline such as potassium hydroxide, sodium hydroxide or lithium hydroxide, films (40 μm thick) of polybenzimidazole (PBI) show conductivity in the 5 × 10−5–10−1 S/cm−1 range, depending on the type of alkali, the time of immersion in the corresponding base bath and the temperature of immersion. It has been shown that PBI has a remarkable capacity to concentrate KOH, even in an alkaline bath of concentration 3 M. The highest conductivity of KOH-doped PBI (9×10−2 S cm−1) at 25°C obtained in this work is higher than the we had obtained previously as optimum values for H2SO4-doped PBI (5 × 10−2 S cm−1 at 25°C) and H3PO4-doped PBI ( 2 × 10−3 S cm−1 at 25°C). PEMFCs based on an alkali-doped PBI membrane were demonstrated, and their characteristics exhibited the same performance as those of PEMFCs based on Nafion® 117. Their development is currently under active investigation.  相似文献   

16.
A triphosphaazatriangulene (H3L) was synthesized through an intramolecular triple phospha‐Friedel–Crafts reaction. The H3L triangulene contains three phosphinate groups and an extended π‐conjugated framework, which enables the stimuli‐responsive reversible transformation of [Cu(HL)(DMSO)?(MeOH)]n, a 3D‐MOF that exhibits reversible sorption characteristics, into (H3L?0.5 [Cu2(OH)4?6 H2O] ?4 H2O), a 1D‐columnar assembled proton‐conducting material. The hydrophilic nature of the latter resulted in a proton conductivity of 5.5×10?3 S cm?1 at 95 % relative humidity and 60 °C.  相似文献   

17.
The hydrolysis of sulfonylamine (HNSO2) results in the formation of sulfuric acid along with ammonia, and is of significant interest due to their negative impact on environment and life on Earth. The formation of H2SO4 through the reaction of HNSO2 with (H2O)2-4 has been studied using high level electronic structure calculations. This hydrolysis reaction is a step-wise process, in the first step a H-atom from H2O is transferred to the N-atom of HNSO2 which results in the formation of NH2, and in the next step, H2SO4, NH3 and water molecule(s) are formed. The results show that the energy barrier associated with the formation of intermediates and product complexes is reduced by 7 to 10 kcal/mol when the number of water molecules is increased from 2 to 4. The rate constant was calculated using canonical variational transition state theory with small curvature tunneling correction over the temperature range of 200 to 1000 K. At 298 K, the calculated rate constant for the formation of intermediate in the first step is 2.24 × 10−16, 1.03 × 10−12, and 2.10 × 10−11 cm3 mol−1 s−1, respectively, for the reaction with water dimer, trimer and tetramer. The calculated enthalpy and free energy show that the reaction corresponding to the formation of H2SO4 is highly exothermic and exoergic in nature.  相似文献   

18.
Developing new materials for anhydrous proton conduction under high-temperature conditions is significant and challenging. Herein, we create a series of highly crystalline covalent organic frameworks (COFs) via a pore engineering approach. We simultaneously engineer the pore geometry (generating concave dodecagonal nanopores) and pore surface (installing multiple functional groups such as −C=N−, −OH, −N=N− and −CF3) to improve the utilization efficiency and host–guest interaction of proton carriers, hence benefiting the enhancement of anhydrous proton conduction. Upon loading with H3PO4, COFs can realize a proton conductivity of 2.33×10−2 S cm−1 under anhydrous conditions, among the highest values of all COF materials. These materials demonstrate good stability and maintain high proton conductivity over a wide temperature range (80–160 °C). This work paves a new way for designing COFs for anhydrous proton conduction applications, which shows great potential as high-temperature proton exchange membranes.  相似文献   

19.
《Polyhedron》1987,6(1):101-103
Ligand substitution properties of the recently characterized pale-yellow [Ir(H2O)6]3+ ion in perchlorate solutions, have been investigated. At 120°C in sealed tubes observations on the exchange with H218O are impaired by a spurious oxidation to purple Ir(IV). Over extended periods at 40°C the ion has been shown to be extremely inert, and the rate constants for substitution of Cl into [Ir(H2O)6]3+ is estimated to be < 2 × 10−9 M−1 S−1.  相似文献   

20.
A few metal–organic frameworks (MOFs), which typically use strong acids as proton sources, display superprotonic conductivity (≈10−1 S cm−1); however, they are rare due to the instability of MOFs in highly acidic conditions. For the first time, we report superprotonic conductivity using a moderately acidic guest, zwitterionic sulfamic acid (HSA), which is encapsulated in MOF-808 and MIL-101. HSA acts not only as a proton source but also as a proton-conducting medium due to its extensive hydrogen bonding ability and zwitterion effect. A new sustained concentration gradient method results in higher HSA encapsulation compared to conventional methods, producing 10HSA@MOF-808-(bSA)2 and 8HSA@MIL-101. These MOFs show impressive superprotonic conductivity of 2.47×10−1 and 3.06×10−1 S cm−1, respectively, at 85 °C and 98 % relative humidity, and maintain stability for 7 days.  相似文献   

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