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1.
l-cysteine undergoes facile electron transfer with heteropoly 10-tungstodivanadophosphate,
[ \textPV\textV \textV\textV \textW 1 0 \textO 4 0 ]5 - , \left[ {{\text{PV}}^{\text{V}} {\text{V}}^{\text{V}} {\text{W}}_{ 1 0} {\text{O}}_{ 4 0} } \right]^{5 - } , at ambient temperature in aqueous acid medium. The stoichiometric ratio of [cysteine]/[oxidant] is 2.0. The products of the
reaction are cystine and two electron-reduced heteropoly blue, [PVIVVIVW10O40]7−. The rates of the electron transfer reaction were measured spectrophotometrically in acetate–acetic acid buffers at 25 °C.
The orders of the reaction with respect to both [cysteine] and [oxidant] are unity, and the reaction exhibits simple second-order
kinetics at constant pH. The pH-rate profile indicates the participation of deprotonated cysteine in the reaction. The reaction
proceeds through an outer-sphere mechanism. For the dianion −SCH2CH(NH3
+)COO−, the rate constant for the cross electron transfer reaction is 96 M−1s−1 at 25 °C. The self-exchange rate constant for the
- \textSCH2 \textCH( \textNH3 + )\textCOO - \mathord | / |
\vphantom - \textSCH2 \textCH( \textNH3 + )\textCOO - ·\textSCH2 \textCH( \textNH3 + )\textCOO - ·\textSCH2 \textCH( \textNH3 + )\textCOO - {{{}^{ - }{\text{SCH}}_{2} {\text{CH}}\left( {{{\text{NH}}_{3}}^{ + } } \right){\text{COO}}^{ - } } \mathord{\left/ {\vphantom {{{}^{ - }{\text{SCH}}_{2} {\text{CH}}\left( {{{\text{NH}}_{3}}^{ + } } \right){\text{COO}}^{ - } } {{}^{ \bullet }{\text{SCH}}_{2} {\text{CH}}\left( {{{\text{NH}}_{3}}^{ + } } \right){\text{COO}}^{ - } }}} \right. \kern-\nulldelimiterspace} {{}^{ \bullet }{\text{SCH}}_{2} {\text{CH}}\left( {{{\text{NH}}_{3}}^{ + } } \right){\text{COO}}^{ - } }} couple was evaluated using the Rehm–Weller relationship. 相似文献
2.
[
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]M (M = K, Tl) reacts with “GaI” to give a series of compounds that feature Ga–Ga bonds, namely [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]Ga→GaI 3, [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]GaGaI 2GaI 2(
\text Hpz\textMe2 {\text{Hpz}}^{{{\text{Me}}_{2} }} ) and [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]Ga(GaI 2) 2Ga[
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ], in addition to the cationic, mononuclear Ga(III) complex {[
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ] 2Ga} +. Likewise, [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]M (M = K, Tl) reacts with (HGaCl 2)
2
and Ga[GaCl 4] to give [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]Ga→GaCl 3, {[
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ] 2Ga}[GaCl 4], and {[
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]GaGa[
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]}[GaCl 4] 2. The adduct [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]Ga→B(C 6F 5) 3 may be obtained via treatment of [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]K with “GaI” followed by addition of B(C 6F 5) 3. Comparison of the deviation from planarity of the GaY 3 ligands in [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]Ga→GaY 3 (Y = Cl, I) and [
\text Tm\textBu\textt {\text{Tm}}^{{{\text{Bu}}^{\text{t}} }} ]Ga→GaY 3, as evaluated by the sum of the Y–Ga–Y bond angles, Σ(Y–Ga–Y), indicates that the [
\text Tm\textBu\textt {\text{Tm}}^{{{\text{Bu}}^{\text{t}} }} ]Ga moiety is a marginally better donor than [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]Ga. In contrast, the displacement from planarity for the B(C 6F 5) 3 ligand of [
\text Tp\textMe2 {\text{Tp}}^{{{\text{Me}}_{2} }} ]Ga→B(C 6F 5) 3 is greater than that of [
\text Tm\textBu\textt {\text{Tm}}^{{{\text{Bu}}^{\text{t}} }} ]Ga→B(C 6F 5) 3, an observation that is interpreted in terms of interligand steric interactions in the former complex compressing the C–B–C
bond angles. 相似文献
3.
Glutathione (GSH) undergoes facile electron transfer with vanadium(V)-substituted Keggin-type heteropolyoxometalates,
[ \text PV\textV \text W 1 1 \text O 4 0 ] 4 - [ {\text{PV}}^{\text{V}} {\text{W}}_{ 1 1} {\text{O}}_{ 4 0} ]^{{ 4 { - }}} (HPA1) and
[ \text PV\textV \text V\textV \text W 1 0 \text O 4 0 ] 5 - [ {\text{PV}}^{\text{V}} {\text{V}}^{\text{V}} {\text{W}}_{ 1 0} {\text{O}}_{ 4 0} ]^{{ 5 { - }}} (HPA2). The kinetics of these reactions have been investigated in phthalate buffers spectrophotometrically at 25 °C in aqueous
medium. One mole of HPA1 consumes one mole of GSH and the product is the one-electron reduced heteropoly blue,
[ \text PV\textIV \text W 1 1 \text O 40 ] 5- [ {\text{PV}}^{\text{IV}} {\text{W}}_{ 1 1} {\text{O}}_{ 40} ]^{ 5- } . But in the GSH-HPA2 reaction, one mole of HPA2 consumes two moles of GSH and gives the two-electron reduced heteropoly blue
[ \text PV\textIV \text V\textIV \text W 10 \text O 40 ] 7- [ {\text{PV}}^{\text{IV}} {\text{V}}^{\text{IV}} {\text{W}}_{ 10} {\text{O}}_{ 40} ]^{ 7- } . Both reactions show overall third-order kinetics. At constant pH, the order with respect to both [HPA] species is one and
order with respect to [GSH] is two. At constant [GSH], the rate shows inverse dependence on [H +], suggesting participation of the deprotonated thiol group of GSH in the reaction. A suitable mechanism has been proposed
and a rate law for the title reaction is derived. The antimicrobial activities of HPA1, HPA2 and
[ \text PV\textV \text V\textV \text V\textV \text W 9 \text O 4 0 ] 6 - [ {\text{PV}}^{\text{V}} {\text{V}}^{\text{V}} {\text{V}}^{\text{V}} {\text{W}}_{ 9} {\text{O}}_{ 4 0} ]^{{ 6 { - }}} (HPA3) against MRSA were tested in vitro in combination with vancomycin and penicillin G. The HPAs sensitize MRSA towards
penicillin G. 相似文献
4.
The oxidation of aquaethylenediaminetetraacetatocobaltate(II) [Co(EDTA)(H 2O)] −2 by N-bromosuccinimide (NBS) in aqueous solution has been studied spectrophotometrically over the pH 6.10–7.02 range at 25 °C.
The reaction is first-order with respect to complex and the oxidant, and it obeys the following rate law:
\textRate = k\textet K 2 K 3 [ \textCo\textII ( \textEDTA )( \textH 2 \textO ) - 2 ]\textT [\textNBS] \mathord | / |
\vphantom [\textNBS] ( [ \textH + ] + K 2 ) ( [ \textH + ] + K 2 ) {\text{Rate}} = k^{\text{et} } K_{ 2} K_{ 3} \left[ {{\text{Co}}^{\text{II}} \left( {\text{EDTA}} \right)\left( {{\text{H}}_{ 2} {\text{O}}} \right)^{ - 2} } \right]_{\text{T}} {{[{\text{NBS}}]} \mathord{\left/ {\vphantom {{[{\text{NBS}}]} {\left( {\left[ {{\text{H}}^{ + } } \right]{ + }K_{ 2} } \right)}}} \right. \kern-\nulldelimiterspace} {\left( {\left[ {{\text{H}}^{ + } } \right]{ + }K_{ 2} } \right)}} 相似文献
5.
A ternary binuclear complex of dysprosium chloride hexahydrate with m-nitrobenzoic acid and 1,10-phenanthroline, [Dy( m-NBA) 3phen] 2·4H 2O ( m-NBA: m-nitrobenzoate; phen: 1,10-phenanthroline) was synthesized. The dissolution enthalpies of [2phen·H 2O(s)], [6 m-HNBA(s)], [2DyCl 3·6H 2O(s)], and [Dy( m-NBA) 3phen] 2·4H 2O(s) in the calorimetric solvent (V DMSO:V MeOH = 3:2) were determined by the solution–reaction isoperibol calorimeter at 298.15 K to be
\Updelta \texts H\textmq \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2phen·H 2O(s), 298.15 K] = 21.7367 ± 0.3150 kJ·mol −1,
\Updelta \texts H\textmq \Updelta_{\text{s}} H_{\text{m}}^{\theta } [6 m-HNBA(s), 298.15 K] = 15.3635 ± 0.2235 kJ·mol −1,
\Updelta \texts H\textmq \Updelta_{\text{s}} H_{\text{m}}^{\theta } [2DyCl 3·6H 2O(s), 298.15 K] = −203.5331 ± 0.2200 kJ·mol −1, and
\Updelta \texts H\textmq \Updelta_{\text{s}} H_{\text{m}}^{\theta } [[Dy( m-NBA) 3phen] 2·4H 2O(s), 298.15 K] = 53.5965 ± 0.2367 kJ·mol −1, respectively. The enthalpy change of the reaction was determined to be
\Updelta \textr H\textmq = 3 6 9. 4 9 ±0. 5 6 \text kJ·\text mol - 1 . \Updelta_{\text{r}} H_{\text{m}}^{\theta } = 3 6 9. 4 9 \pm 0. 5 6 \;{\text{kJ}}\cdot {\text{mol}}^{ - 1} . According to the above results and the relevant data in the literature, through Hess’ law, the standard molar enthalpy of
formation of [Dy( m-NBA) 3phen] 2·4H 2O(s) was estimated to be
\Updelta \textf H\textmq \Updelta_{\text{f}} H_{\text{m}}^{\theta } [[Dy( m-NBA) 3phen] 2·4H 2O(s), 298.15 K] = −5525 ± 6 kJ·mol −1. 相似文献
6.
From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M + (aq) + NaL + (nb) ⇔ ML + (nb) + Na + (aq) taking place in the two-phase water–nitrobenzene system (M + = H 3O +,
\text NH4+ {\text{NH}}_{4}{}^{+} , Ag +, Tl +; L = hexaethyl p- tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants
of the ML + complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following order:
\text Ag + < NH 4 + < \text H 3 \text O + < \text Na + < \text Tl + . {\text{Ag}}^{ + } \, < \,\hbox{NH}_{4}{}^{ + } \, < \,{\text{H}}_{ 3} {\text{O}}^{ + } \, < \,{\text{Na}}^{ + } \, < \,{\text{Tl}}^{ + }. 相似文献
7.
Combustion calorimetry, Calvet-drop sublimation calorimetry, and the Knudsen effusion method were used to determine the standard
( p
o = 0.1 MPa) molar enthalpies of formation of monoclinic (form I) and gaseous paracetamol, at T = 298.15 K:
\Updelta \textf H\textm\texto ( \text C 8 \text H 9 \text O 2 \text N,\text cr I ) = - ( 4 10.4 ±1. 3)\text kJ \text mol - 1 \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ cr I}}} \right) = - ( 4 10.4 \pm 1. 3){\text{ kJ}}\;{\text{mol}}^{ - 1} and
\Updelta \textf H\textm\texto ( \text C 8 \text H 9 \text O 2 \text N,\text g ) = - ( 2 80.5 ±1. 9)\text kJ \text mol - 1 . \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ g}}} \right) = - ( 2 80.5 \pm 1. 9){\text{ kJ}}\;{\text{mol}}^{ - 1} . From the obtained
\Updelta \textf H\textm\texto ( \text C 8 \text H 9 \text O 2 \text N,\text cr I ) \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ cr I}}} \right) value and published data, it was also possible to derive the standard molar enthalpies of formation of the two other known
polymorphs of paracetamol (forms II and III), at 298.15 K:
\Updelta \textf H\textm\texto ( \text C 8 \text H 9 \text O 2 \text N,\text crII ) = - ( 40 8.4 ±1. 3)\text kJ \text mol - 1 \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ crII}}} \right) = - ( 40 8.4 \pm 1. 3){\text{ kJ}}\;{\text{mol}}^{ - 1} and
\Updelta \textf H\textm\texto ( \text C 8 \text H 9 \text O 2 \text N,\text crIII ) = - ( 40 7.4 ±1. 3)\text kJ \text mol - 1 . \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ crIII}}} \right) = - ( 40 7.4 \pm 1. 3){\text{ kJ}}\;{\text{mol}}^{ - 1} . The proposed
\Updelta \textf H\textm\texto ( \text C 8 \text H 9 \text O 2 \text N,\text g ) \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{O}}_{ 2} {\text{N}},{\text{ g}}} \right) value, together with the experimental enthalpies of formation of acetophenone and 4′-hydroxyacetophenone, taken from the
literature, and a re-evaluated enthalpy of formation of acetanilide,
\Updelta \textf H\textm\texto ( \text C 8 \text H 9 \text ON,\text g ) = - ( 10 9. 2 ± 2. 2)\text kJ \text mol - 1 , \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{C}}_{ 8} {\text{H}}_{ 9} {\text{ON}},{\text{ g}}} \right) = - ( 10 9. 2\,\pm\,2. 2){\text{ kJ}}\;{\text{mol}}^{ - 1} , were used to assess the predictions of the B3LYP/cc-pVTZ and CBS-QB3 methods for the enthalpy of a isodesmic and isogyric
reaction involving those species. This test supported the reliability of the theoretical methods, and indicated a good thermodynamic
consistency between the
\Updelta \textf H\textm\texto \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} (C 8H 9O 2N, g) value obtained in this study and the remaining experimental data used in the
\Updelta \textr H\textm\texto \Updelta_{\text{r}} H_{\text{m}}^{\text{o}} calculation. It also led to the conclusion that the presently recommended enthalpy of formation of gaseous acetanilide in
Cox and Pilcher and Pedley’s compilations should be corrected by ~20 kJ mol −1. 相似文献
8.
In the present work the uranyl hexacyanoferrate (K 2UO 2[Fe(CN) 6]) is deposited on the palladized aluminum (Pd-Al) electrode from a
\text UO22 + + \text Fe( \text CN ) 6 - 3 {\text{UO}}_{2}^{2 + } + {\text{Fe}}\left( {\text{CN}} \right)_{6}^{ - 3} solution. Then the anodic stripping chronopotentiometry (ASCP) was used to strip the K 2UO 2[Fe(CN) 6] from the Pd-Al surface. The operational conditions including: pH, K 3Fe(CN) 6 concentration, deposition potential, deposition time and stripping current were optimized. The ASCP calibration graph was
linear in concentration range 10–460 μM. of
\text UO22 + {\text{UO}}_{2}^{2 + } and the detection limit was 8.5 μM. The interference of some concomitant ions during the deposition process of K 2UO 2[Fe(CN) 6] was studied. The proposed method was successfully applied for analysis of some uranium mineral ores. 相似文献
9.
The assumption that potassium permanganate may serve as a kinetics standard in solid decomposition kinetics made a priori
on the basis of the mechanism of the congruent dissociative vaporization of KMnO 4 and its crystal structure was successfully supported experimentally. As expected, the decomposition rate of KMnO 4 does not depend on the kind of foreign gas (He, air, CO 2 and Ar) and on the measurement technique (isothermal or dynamic). Other requirements for KMnO 4 as an ideal kinetics standard are satisfied as well. The use of the third-law method for determining the molar enthalpy of
a reaction
( \Updelta \textr H\textT\texto / n ) \left( {\Updelta_{\text{r}} H_{\text{T}}^{\text{o}} / \nu } \right) provides an excellent reproducibility of results. The mean value of
\Updelta \textr H\textT\texto / n \Updelta_{\text{r}} H_{\text{T}}^{\text{o}} / \nu from 12 experiments in different gases is 138.3 ± 0.6 kJ mol −1, which coincides with the value of 138.1 kJ mol −1 calculated from the isothermal measurements in different gases by the second-law method. As predicted by theory, the random
errors of the second-law and Arrhenius plot methods are 10–20 times greater. In addition, the use of these methods in the
case of dynamic measurements is related to large systematic errors caused by an inaccurate selection of the geometrical (contraction)
model. The third-law method is practically free of these errors. 相似文献
10.
The standard molar Gibbs free energy of formation of YRhO 3(s) has been determined using a solid-state electrochemical cell wherein calcia-stabilized zirconia was used as an electrolyte.
The cell can be represented by:
( - )\text Pt - Rh/{ \text Y2\text O\text3( \text s ) + \text YRh\text O3( \text s ) + \text Rh( \text s ) }//\text CSZ//\text O2( p( \text O2 ) = 21.21 \text kPa )/\text Pt - Rh( + ) \left( - \right){\text{Pt - Rh/}}\left\{ {{{\text{Y}}_2}{{\text{O}}_{\text{3}}}\left( {\text{s}} \right) + {\text{YRh}}{{\text{O}}_3}\left( {\text{s}} \right) + {\text{Rh}}\left( {\text{s}} \right)} \right\}//{\text{CSZ//}}{{\text{O}}_2}\left( {p\left( {{{\text{O}}_2}} \right) = 21.21\;{\text{kPa}}} \right)/{\text{Pt - Rh}}\left( + \right) . The electromotive force was measured in the temperature range from 920.0 to 1,197.3 K. The standard molar Gibbs energy of
the formation of YRhO 3(s) from elements in their standard state using this electrochemical cell has been calculated and can be represented by:
D \textfG\texto{ \text YRh\text O3( \text s ) }/\text kJ \text mo\text l - 1( ±1.61 ) = - 1,147.4 + 0.2815 T ( \text K ) {\Delta_{\text{f}}}{G^{\text{o}}}\left\{ {{\text{YRh}}{{\text{O}}_3}\left( {\text{s}} \right)} \right\}/{\text{kJ}}\;{\text{mo}}{{\text{l}}^{ - 1}}\left( {\pm 1.61} \right) = - 1,147.4 + 0.2815\;T\;\left( {\text{K}} \right) . Standard molar heat capacity Cop,m C^{o}_{{p,m}} ( T) of YRhO 3(s) was measured using a heat flux-type differential scanning calorimeter in two different temperature ranges from 127 to
299 K and 305 to 646 K. The heat capacity in the higher temperature range was fitted into a polynomial expression and can
be represented by: $ {*{20}{c}} {\mathop C\nolimits_{p,m}^{\text{o}} \left( {{\text{YRh}}{{\text{O}}_3},{\text{s,}}T} \right)\left( {{\text{J}}\;{{\text{K}}^{ - 1}}{\text{mo}}{{\text{l}}^{ - 1}}} \right)} & { = 109.838 + 23.318 \times {{10}^{ - 3}}T\left( {\text{K}} \right)} & { - 12.5964 \times {{10}^5}/{T^2}\left( {\text{K}} \right).} \\ {} & {\left( {305 \leqslant T\left( {\text{K}} \right) \leqslant 646} \right)} & {} \\ $ \begin{array}{*{20}{c}} {\mathop C\nolimits_{p,m}^{\text{o}} \left( {{\text{YRh}}{{\text{O}}_3},{\text{s,}}T} \right)\left( {{\text{J}}\;{{\text{K}}^{ - 1}}{\text{mo}}{{\text{l}}^{ - 1}}} \right)} & { = 109.838 + 23.318 \times {{10}^{ - 3}}T\left( {\text{K}} \right)} & { - 12.5964 \times {{10}^5}/{T^2}\left( {\text{K}} \right).} \\ {} & {\left( {305 \leqslant T\left( {\text{K}} \right) \leqslant 646} \right)} & {} \\ \end{array} The heat capacity of YRhO 3(s) was used along with the data obtained from the electrochemical cell to calculate the standard enthalpy and entropy of
formation of the compound at 298.15 K. 相似文献
11.
This article reports the values of the standard ( p
o = 0.1 MPa) molar enthalpies of formation, in the gaseous phase,
\Updelta \textf H\textm\texto ( \text g ), {{\Updelta}}_{\text{f}} H_{\text{m}}^{\text{o}} \left( {\text{g}} \right), at T = 298.15 K, of 2-acetyl-5-nitrothiophene and 5-nitro-2-thiophenecarboxaldehyde as −(48.8 ± 1.6) and (4.4 ± 1.3) kJ mol −1, respectively. These values were derived from experimental thermodynamic parameters, namely, the standard ( p
o = 0.1 MPa) molar enthalpies of formation, in the crystalline phase,
\Updelta \textf H\textm\texto ( \text cr ) , {{\Updelta}}_{\text{f}} H_{\text{m}}^{\text{o}} \left( {\text{cr}} \right) , at T = 298.15 K, obtained from the standard molar enthalpies of combustion,
\Updelta \textc H\textm\texto , {{\Updelta}}_{\text{c}} H_{\text{m}}^{\text{o}} , measured by rotating bomb combustion calorimetry, and from the standard molar enthalpies of sublimation, at T = 298.15 K, determined from the temperature–vapour pressure dependence, obtained by the Knudsen mass loss effusion method.
The results are interpreted in terms of enthalpic increments and the enthalpic contribution of the nitro group in the substituted
thiophene ring is compared with the same contribution in other structurally similar compounds. 相似文献
12.
The molar enthalpies of solution of 2-aminopyridine at various molalities were measured at T=298.15 K in double-distilled water by means of an isoperibol solution-reaction calorimeter. According to Pitzer’s theory,
the molar enthalpy of solution of the title compound at infinite dilution was calculated to be D solHm¥ = 14.34 kJ·mol -1\Delta_{\mathrm{sol}}H_{\mathrm{m}}^{\infty} = 14.34~\mbox{kJ}\cdot\mbox{mol}^{-1}, and Pitzer’s ion interaction parameters b MX(0)L, b MX(1)L\beta_{\mathrm{MX}}^{(0)L}, \beta_{\mathrm{MX}}^{(1)L}, and CMXfLC_{\mathrm{MX}}^{\phi L} were obtained. Values of the relative apparent molar enthalpies (
φ
L) and relative partial molar enthalpies of the compound ([`( L)] 2)\bar{L}_{2}) were derived from the experimental enthalpies of solution of the compound. The standard molar enthalpy of formation of the
cation C 5H 7N 2 +\mathrm{C}_{5}\mathrm{H}_{7}\mathrm{N}_{2}^{ +} in aqueous solution was calculated to be D fHmo(C 5H 7N 2+,aq)=-(2.096±0.801) kJ·mol -1\Delta_{\mathrm{f}}H_{\mathrm{m}}^{\mathrm{o}}(\mathrm{C}_{5}\mathrm{H}_{7}\mathrm{N}_{2}^{+},\mbox{aq})=-(2.096\pm 0.801)~\mbox{kJ}\cdot\mbox{mol}^{-1}. 相似文献
13.
LiMnPO 4, with a particle size of 50–150 nm, was prepared by oleic acid-assisted solid-state reaction. The materials were characterized
by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The electrochemical
properties of the materials were investigated by galvanostatic cycling. It was found that the introduction of oleic acid in
the precursor led to smaller particle size and more homogeneous size distribution in the final products, resulting in improved
electrochemical performance. The electrochemical performance of the sample could be further enhanced by Co doping. The mechanism
for the improvement of the electrochemical performance was investigated by Li-ion chemical diffusion coefficient
( [( D)\tilde] \textLi ) \left( {{{\tilde{D}}_{\text{Li}}}} \right) and electrochemical impedance spectroscopy measurements. The results revealed that the
[( D)\tilde] \textLi {\tilde{D}_{\text{Li}}} values of LiMnPO 4 measured by cyclic voltammetry method increase from 9.2 × 10 −18 to 3.0 × 10 −17 cm 2 s −1 after Co doping, while the charge transfer resistance ( R
ct) can be decreased by Co doping. 相似文献
14.
Theoretical study of several para-substituted O-nitrosyl carboxylate compounds has been performed using density functional B3LYP method with 6-31G(d,p) basis set. Geometries obtained from DFT calculation were used to perform natural bond orbital analysis. It is noted that weakness in the O 3–N 2 sigma bond is due to $ n_{{{\text{O}}_{1} }} \to \sigma_{{{\text{O}}_{3} - {\text{N}}_{2} }}^{*} Theoretical study of several para-substituted O-nitrosyl carboxylate compounds has been performed using density functional B3LYP method with 6-31G(d,p) basis set. Geometries
obtained from DFT calculation were used to perform natural bond orbital analysis. It is noted that weakness in the O3–N2 sigma bond is due to
n\textO1 ? s\textO3 - \textN2 * n_{{{\text{O}}_{1} }} \to \sigma_{{{\text{O}}_{3} - {\text{N}}_{2} }}^{*} delocalization and is responsible for the longer O3–N2 bond lengths in para-substituted O-nitrosyl carboxylate compounds. It is also noted that decreased occupancy of the localized
s\textO3 -\textN2 \sigma_{{{\text{O}}_{3} --{\text{N}}_{2} }} orbital in the idealized Lewis structure, or increased occupancy of
s\textO3 - \textN2 * \sigma_{{{\text{O}}_{3} - {\text{N}}_{2} }}^{*} of the non-Lewis orbital, and their subsequent impact on molecular stability and geometry (bond lengths) are related with
the resulting p character of the corresponding sulfur natural hybrid orbital of
s\textO3 -\textN2 \sigma_{{{\text{O}}_{3} --{\text{N}}_{2} }} bond orbital. In addition, the charge transfer energy decreases with the increase of the Hammett constants of substituent
groups and the partial charges distribution on the skeletal atoms may approve anticipating that the electrostatic repulsion
or attraction between atoms can give a significant contribution to the intra- and intermolecular interaction. 相似文献
15.
A high-performance gas–liquid transmission device (HPTD) was described in this paper. To investigate the HPTD mass transfer
characteristics, the overall volumetric mass transfer coefficients,
K\textLa,\textCO2 \textA K_{{\text{La}},{\text{CO}}_2 }^{\text{A}} for the absorption of gaseous CO 2 and
K\textLa,\textO2 \textD K_{{\text{La}},{\text{O}}_2 }^{\text{D}} for the desorption of dissolved O 2 were determined, respectively, by titration and dissolved oxygen electrode. The mass transfer capability of carbon dioxide
was compared with that of dissolved oxygen in the device, and the operating conditions were optimized to suit for the large-scale
enclosed micro-algae cultivation. Based on the effectiveness evaluation of the HPTD applied in one enclosed flat plate Spirulina culture system, it was confirmed that the HPTD can satisfy the demand of the enclosed system for carbon supplement and excessive
oxygen removal. 相似文献
16.
Abstract The title complexes and have been synthesized in excellent yields by reacting Co(OAc) 2·4H 2O with H 2L 1 and H 2L 2, respectively, in acetonitrile solution. Here, [L 1] 2− and [L 2] 2− are the deprotonated forms of N,N-bis(2-hydroxybenzyl)- N′, N′-dimethylethylenediamine and N,N-bis(2-hydroxybenzyl)-2-picolylamine, respectively. The crystal structures of and were determined by x-ray crystallography. In , each cobalt atom has distorted trigonal bipyramid geometry, while in , each cobalt atom has distorted octahedral geometry. Variable temperature magnetic moment measurements show weak antiferromagnetic
interaction in . The magnetic characterization for is in agreement with the presence of Co(II) and Co(III) centers.
Graphical Abstract The title complexes and have been synthesized in excellent yields by reacting Co(OAc) 2·4H 2O with dianionic N 2O 2 coordinating ligands. In complex 1, each cobalt atom has distorted trigonal bipyramid geometry, while in complex 2, each
cobalt atom has distorted octahedral geometry. Variable temperature magnetic moment measurements show weak antiferromagnetic
interaction in complex 1. The magnetic characterization for complex 2 is in agreement with the presence of Co(II) and Co(III)
centers.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
Extraction of microamounts of cesium by a nitrobenzene solution of ammonium dicarbollylcobaltate
( \text NH 4 + \text B - ) ( {{\text{NH}}_{ 4}^{ + } {\text{B}}^{ - } }) and thallium dicarbollylcobaltate
( \text Tl + \text B - ) ( {{\text{Tl}}^{ + } {\text{B}}^{ - } }) in the presence of 2,3-naphtho-15-crown-5 (N15C5, L) has been investigated. The equilibrium data have been explained assuming
that the complexes
\text ML + {\text{ML}}^{ + } and
\text ML 2 + {\text{ML}}_{ 2}^{ + }
( \text M + = \text NH4 + ,\text Tl + ,\text Cs + ) ( {{\text{M}}^{ + } = {\text{NH}}_{4}^{ + } ,{\text{Tl}}^{ + } ,{\text{Cs}}^{ + } } ) are present in the organic phase. The stability constants of the
\text ML + {\text{ML}}^{ + } and
\text ML2 + {\text{ML}}_{2}^{ + } species
( \text M + = \text NH4 + ,\text Tl + ) ( {{\text{M}}^{ + } = {\text{NH}}_{4}^{ + } ,{\text{Tl}}^{ + } }) in nitrobenzene saturated with water have been determined. It was found that the stability of the complex cations
\text ML + {\text{ML}}^{ + } and
\text ML2 + {\text{ML}}_{2}^{ + }
(\text M + = \text NH4 + ,\text Tl + ,\text Cs + ; \text L = \text N15\text C5) ({{\text{M}}^{ + } = {\text{NH}}_{4}^{ + } ,{\text{Tl}}^{ + } ,{\text{Cs}}^{ + } ;\;{\text{L}} = {\text{N}}15{\text{C}}5}) in the mentioned medium increases in the
\text Cs + < \text NH4 + < \text Tl + {\text{Cs}}^{ + }\,<\, {\text{NH}}_{4}^{ + }\,<\,{\text{Tl}}^{ + } order. 相似文献
18.
Extraction of microamounts of calcium and strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H +B −) in the presence of diphenyl- N,N-dibutylcarbamoylmethyl phosphine oxide (DPDBCMPO, L) has been investigated. The equilibrium data have been explained assuming
that the species HL +,
\text HL2 + {\text{HL}}_{2}^{ + } , CaL 2+,
\text CaL 2 2 + {\text{CaL}}_{ 2}^{{ 2 { + }}} ,
\text CaL 3 2 + {\text{CaL}}_{ 3}^{{ 2 { + }}} , SrL 2+,
\text SrL 2 2 + {\text{SrL}}_{ 2}^{{ 2 { + }}} ,
\text SrL 3 2 + {\text{SrL}}_{ 3}^{{ 2 { + }}} and
\text SrL 4 2 + {\text{SrL}}_{ 4}^{{ 2 { + }}} are extracted into the organic phase. The values of extraction and stability constants of the cationic complexes in nitrobenzene
saturated with water have been determined. In the considered nitrobenzene medium, it was found that the stability constants
of the complexes CaL 2+,
\text CaL 2 2 + {\text{CaL}}_{ 2}^{{ 2 { + }}} and
\text CaL 3 2 + {\text{CaL}}_{ 3}^{{ 2 { + }}} , where L is DPDBCMPO, are somewhat higher than those of the corresponding complex species SrL 2+,
\text SrL 2 2 + {\text{SrL}}_{ 2}^{{ 2 { + }}} and
\text SrL 3 2 + {\text{SrL}}_{ 3}^{{ 2 { + }}} . 相似文献
19.
The mixed-valence 24-vanadophosphate
( 1) has been synthesized and characterized in the solid state by IR, magnetism, EPR, XPS, and elemental analysis. Single-crystal
X-ray analysis was carried out on ( Na-1), which crystallizes in the triclinic system, space group , with a = 17.168(3) ?, b = 18.1971(14) ?, c = 20.1422(13) ?, α = 114.753(3)°, β = 99.390(4)°, γ = 95.124(4)°, and Z = 2. Polyanion 1 has an unusual, open structure composed of 2 Ru IIIO 6 octahedra, 2 V IVO 6 octahedra, 14 V VO 5 square-pyramids, 8 V VO 4 tetrahedra, and 2 PO 4 tetrahedra which are all directly linked via edges and corners. The outer surface of 1 is decorated with six Ru II( dmso) 3 groups. XPS studies on Na-1 confirm the presence of 2 Ru III and 6 Ru II as well as 22 V V and 2 V IV centers. Magnetic susceptibility data on Na-1 show that the V IV–Ru III pairs are coupled antiferromagnetically, with J
1 = −13 K and J
2 ∼ −3 K. We did not detect any peak in our EPR measurements on Na-1, thus supporting the conclusion that Na-1 is diamagnetic in its ground state.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
In Memoriam Prof. F. A. Cotton 相似文献
20.
Abstract Experimental densities ρ, viscosities η, and refractive indices n
D of the ternary mixtures consisting of 2-methyltetrahydrofuran + chlorobenzene + cyclopentanone and constituted binary mixtures
were measured at T = 298.15 K for the liquid region and at ambient pressure for the whole composition range. Excess molar volumes
V\textm\textEV_{\text{m}}^{\text{E}}, deviations in the viscosity Δ η, and deviations in the refractive index Δ n
D from the mole fraction average for the mixtures were derived from the experimental data. The excess partial molar volumes
V\textm,i\textEV_{{\text{m}},i}^{\text{E}} were also calculated. The binary and ternary data of
V\textm\textEV_{\text{m}}^{\text{E}}, Δ η, and Δ n
D were correlated as a function of the mole fraction by using the Redlich–Kister and the Cibulka equations, respectively. McAllister’s
three-body interaction model is used for correlating the kinematic viscosity of binary mixtures with the mole fraction. 相似文献
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