Voltammetric sensor for glutathione determination based on ferrocene-modified carbon paste electrode

The electrocatalytic oxidation of glutathione (GSH) has been studied at the surface of ferrocene-modified carbon paste electrode (FMCPE). Cyclic voltammetry (CV), double potential step chronoamperometry, and differential pulse voltammetry (DPV) techniques were used to investigate the suitability of incorporation of ferrocene into FMCPE as a mediator for the electrocatalytic oxidation of GSH in buffered aqueous solution. Results showed that pH 7.00 is the most suitable for this purpose. In the optimum condition (pH 7.00), the electrocatalytic ability of about 480 mV can be found and the heterogeneous rate constant of catalytic reaction was calculated as . Also, the diffusion coefficient of glutathione, D, was found to be 3.61 × 10^–5 cm² s⁻¹. The electrocatalytic oxidation peak current of glutathione at the surface of this modified electrode was linearly dependent on the GSH concentration and the linear analytical curves were obtained in the ranges of 3.2 × 10^–5 M–1.6 × 10^–3 M and 2.2 × 10^–6 M–3.5 × 10^–3 M with cyclic voltammetry and differential pulse voltammetry methods, respectively. The detection limits (3σ) were determined as 1.8 × 10^–5 M and 2.1 × 10^–6 M using CV and DPV, respectively. Finally, the electrocatalytic oxidation of GSH at the surface of this modified electrode can be employed as a new method for the voltammetric determination of glutathione in real samples such as human plasma.     

Electrocatalytic oxidation of nitrite at a terpyridine manganese(II) complex modified carbon past electrode

A carbon past electrode modified with [Mn(H₂O)(N₃)(NO₃)(pyterpy)], ( \textpyterpy = 4￠- ( 4 - \textpyridyl ) - 2,2￠:\text6￠,\text2￠￠- \textterpyridine ) \left( {{\text{pyterpy}} = 4\prime - \left( {4 - {\text{pyridyl}}} \right) - 2,2\prime:{\text{6}}\prime,{\text{2}}\prime\prime - {\text{terpyridine}}} \right) complex have been applied to the electrocatalytic oxidation of nitrite which reduced the overpotential by about 120 mV with obviously increasing the current response. Relative standard deviations for nitrite determination was less than 2.0%, and nitrite can be determined in the ranges of 5.00 × 10⁻⁶ to 1.55 × 10⁻² mol L⁻¹, with a detection limit of 8 × 10⁻⁷ mol L⁻¹. The treatment of the voltammetric data showed that it is a pure diffusion-controlled reaction, which involves one electron in the rate-determining step. The rate constant k′, transfer coefficient α for the catalytic reaction, and diffusion coefficient of nitrite in the solution, D, were found to be 1.4 × 10⁻², 0.56× 10⁻⁶, and 7.99 × 10⁻⁶ cm² s⁻¹, respectively. The mechanism for the interaction of nitrite with the Mn(II) complex modified carbon past electrode is proposed. This work provides a simple and easy approach to detection of nitrite ion. The modified electrode indicated reproducible behavior, anti-fouling properties, and stability during electrochemical experiments, making it particularly suitable for the analytical purposes.     

Effect of the cathode structure on the electrochemical performance of anode-supported solid oxide fuel cells

The study elementarily investigated the effect of the cathode structure on the electrochemical performance of anode-supported solid oxide fuel cells. Four single cells were fabricated with different cathode structures, and the total cathode thickness was 15, 55, 85, and 85 μm for cell-A, cell-B, cell-C, and cell-D, respectively. The cell-A, cell-B, and cell-D included only one cathode layer, which was fabricated by ( \textLa_0.74 \textBi_0.10 \textSr_0.16 )\textMnO_{3 - d} \left( {{\text{La}}_{0.74} {\text{Bi}}_{0.10} {\text{Sr}}_{0.16} } \right){\text{MnO}}_{{3 - \delta }} (LBSM) electrode material. The cathode of the cell-C was composed of a ( \textLa_0.74 \textBi_0.10 \textSr_0.16 )\textMnO_{3 - d} - ( \textBi_0.7 \textEr_0.3 \textO_1.5 ) \left( {{\text{La}}_{0.74} {\text{Bi}}_{0.10} {\text{Sr}}_{0.16} } \right){\text{MnO}}_{{3 - \delta }} - \left( {{\text{Bi}}_{0.7} {\text{Er}}_{0.3} {\text{O}}_{1.5} } \right) (LBSM–ESB) cathode functional layer and a LBSM cathode layer. Different cathode structures leaded to dissimilar polarization character for the four cells. At 750°C, the total polarization resistance (R _p) of the cell-A was 1.11, 0.41 and 0.53 Ω cm² at the current of 0, 400, and 800 mA, respectively, and that of the cell-B was 1.10, 0.39, and 0.23 Ω cm² at the current of 0, 400, and 800 mA, respectively. For cell-C and cell-D, their polarization character was similar to that of the cell-B and R _p also decreased with the increase of the current. The maximum power density was 0.81, 1.01, 0.79, and 0.43 W cm⁻² at 750°C for cell-D, cell-C, cell-B, and cell-A, respectively. The results demonstrated that cathode structures evidently influenced the electrochemical performance of anode-supported solid oxide fuel cells.     

Novel quintet and triplet (nitrenoethynyl)halomethylenes at theoretical levels

Coupling of a local triplet carbene with a local triplet nitrene through an acetylene linkage gives a new brand of high spin quintet minima ( \textX-\textC ^··-\textC o \textC-\textN _·· ^·· {\text{X}}{-}\mathop {\text{C}}\limits^{ \cdot \cdot }{-}{\text{C}} \equiv {\text{C}}{-}\mathop {\text{N}}\limits_{ \cdot \cdot }^{ \cdot \cdot } , where X = H, F, Cl, Br), which are rather experimentally unreachable. Placing the same linkage between the local open-shell singlet carbene (σ¹π¹) and the local triplet nitrene (π¹π¹) gives triplet minima which are 54–56 kcal/mol more stable than their corresponding quintets. The carbenic angles in both quintets and triplets follow electropositivity of X (H > Br > Cl > F), with every divalent angle in quintet being smaller than the corresponding one in the triplet. Finally no reactive intermediate is observed through connecting singlet states of carbene and nitrene subunits which gives a neutral linear molecule with X–C≡C–C≡N formula, and show about 70 kcal/mol more stability than the corresponding triplet states. Our results are compared at B3LYP, HF, MP2, MP4(SDTQ), CCSD(T), and QCISD(T) levels using 6-311++G** basis set.     

$$ {{\text{C}}_{\alpha }} - {\text{C}} $$ Bond Cleavage of the Peptide Backbone in MALDI In-Source Decay Using Salicylic Acid Derivative Matrices

The use of 5-formylsalicylic acid (5-FSA) and 5-nitrosalicylic acid (5-NSA) as novel matrices for in-source decay (ISD) of peptides in matrix-assisted laser desorption/ionization (MALDI) is described. The use of 5-FSA and 5-NSA generated a- and x-series ions accompanied by oxidized peptides [M – 2 H + H]⁺. The preferential formation of a- and x-series ions was found to be dependent on the hydrogen-accepting ability of matrix. The hydrogen-accepting ability estimated from the ratio of signal intensity of oxidized product [M – 2 H + H]⁺ to that of non-oxidized protonated molecule [M + H]⁺ of peptide was of the order 5-NSA > 5-FSA > 5-aminosalicylic acid (5-ASA) ≒ 2,5-dihydroxyl benzoic acid (2,5-DHB) ≒ 0. The results suggest that the hydrogen transfer reaction from peptide to 5-FSA and 5-NSA occurs during the MALDI-ISD processes. The hydrogen abstraction from peptides results in the formation of oxidized peptides containing a radical site on the amide nitrogen with subsequent radical-induced cleavage at the \textC_a - \textC {{\text{C}}_{\alpha }} - {\text{C}} bond, leading to the formation of a- and x-series ions. The most significant feature of MALDI-ISD with 5-FSA and 5-NSA is the specific cleavage of the \textC_a - \textC {{\text{C}}_{\alpha }} - {\text{C}} bond of the peptide backbone without degradation of side-chain and post-translational modifications (PTM). The matrix provides a useful complementary method to conventional MALDI-ISD for amino acid sequencing and site localization of PTMs in peptides.     

Stability constants of some metal cation complexes of tetraphenyl p - tert -butylcalix[4]arene tetraketone in nitrobenzene saturated with water

Abstract  

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium \textM^{2 +} ( \textaq ) + 1 ·\textSr^{2 +} ( \textnb ) \rightleftarrows 1 ·\textM^{2 +} ( \textnb ) + \textSr^{2 +} ( \textaq ) {\text{M}}^{2 + } \left( {\text{aq}} \right) + {\mathbf{1}} \cdot {\text{Sr}}^{2 + } \left( {\text{nb}} \right) \rightleftarrows {\mathbf{1}} \cdot {\text{M}}^{2 + } \left( {\text{nb}} \right) + {\text{Sr}}^{2 + } \left( {\text{aq}} \right) taking place in the two-phase water–nitrobenzene system (M²⁺ = Ca²⁺, Ba²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, UO₂ ²⁺, Mn²⁺, Co²⁺, Ni²⁺; 1 = tetraphenyl p-tert-butylcalix[4]arene tetraketone; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Further, the stability constants of the 1 · M²⁺ complexes in water-saturated nitrobenzene were calculated; they were found to increase in the cation order Ba²⁺, Mn²⁺ < Co²⁺ < Cu²⁺, Ni²⁺ < Zn²⁺, Cd²⁺, UO₂ ²⁺ < Ca²⁺ < Pb²⁺.     

Extraction and DFT study on the complexation of the cesium cation with dibenzo-21-crown-7

From extraction experiments and γ-activity measurements, the extraction constant corresponding to the equilibrium \textCs ⁺ ( \textaq ) + \textA ^- ( \textaq ) + 1( \textnb )\underset \rightleftharpoons 1·\textCs ⁺ ( \textnb ) + \textA ^- ( \textnb ) {\text{Cs}}^{ + } \left( {\text{aq}} \right) + {\text{A}}^{ - } \left( {\text{aq}} \right) + {\mathbf{1}}\left( {\text{nb}} \right)\underset {} \rightleftharpoons {\mathbf{1}}\cdot{\text{Cs}}^{ + } \left( {\text{nb}} \right) + {\text{A}}^{ - } \left( {\text{nb}} \right) taking place in the two-phase water-nitrobenzene system (A⁻ = picrate, 1 = dibenzo-21-crown-7; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log K _ex (1·Cs⁺, A⁻) = 4.4 ± 0.1. Further, the stability constant of the 1·Cs⁺ complex in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log β_nb (1·Cs⁺) = 6.3 ± 0.1. Finally, by using quantum mechanical DFT calculations, the most probable structure of the resulting cationic complex species 1·Cs⁺ was solved.     

Effect of Ammonium Salts on the Volumetric and Viscometric Behavior of D(+)-Glucose,D(−)-Fructose and Sucrose in Aqueous Solutions at 25°C

Apparent molar volumes, V _φ, and viscosity, η, of D(+)-glucose, D(−)-fructose and sucrose in water and in 0.02, 0.05, 0.5, 1.0 and 2.0 mol·kg⁻¹ aqueous solutions of ammonium bromide, tetraethylammonium bromide and tetra-n-butylammonium bromide have been determined at 25 °C from density and efflux time measurements by using a vibrating-tube digital densimeter and a capillary viscometer, respectively. Partial molar volumes, , at infinite dilution that were extrapolated from the V _φ data were used to obtain the corresponding transfer volumes, , for saccharides from water to different aqueous solutions of co-solutes. The Jones-Dole equation viscosity B-coefficients were obtained from the viscosity data. Positive values of were obtained for the saccharides in the presence of ammonium bromide, whereas both positive and negative values were obtained in the presence of tetraethylammonium and tetra-n-butylammonium bromides. The negative values at very low concentrations have small magnitudes. Volumetric interaction coefficients have been calculated by using the McMillan-Mayer theory and Gibbs energies of activation of viscous flow have been calculated by using Feakin’s transition-state theory equation. The parameters obtained from the volumetric and viscometric studies were used to understand various mixing effects due to the interactions between saccharides and ammonium salts in aqueous solutions.     

Kinetic and mechanistic studies on the substitution of aqua ligands from <Emphasis Type="Italic">cis</Emphasis>-diaqua-<Emphasis Type="Italic">bis</Emphasis>-(bypyridyl)-ruthenium(II) ion by vic-dioximes

Kinetics of aqua ligand substitution from cis-[Ru(bpy)₂(H₂O)₂]²⁺ by three vicinal dioximes, namely dimethylglyoxime (L¹H), 1,2-cyclohexane dionedioxime (L²H) and α-furil dioxime (L³H) have been studied spectrophotometrically in the 45–60 °C temperature range. The rate constants increase with increasing dioxime concentration and approach a limiting condition. We propose the following rate law for the reaction in the 3.5–5.5 pH range: where k ₂ is the interchange rate constant from outer sphere to inner sphere complex and K _E is the outer sphere association equilibrium constant. Activation parameters were calculated from the Eyring plots for all three systems: ΔH ^≠ = 59.2 ± 8.8, 63.1 ± 6.8 and 69.7 ± 8.5 kJ mol⁻¹, ΔS ^≠ = −122 ± 27, −117 ± 21 and −99 ± 26 J K⁻¹ mol⁻¹ for L¹H, L²H and L³H, respectively. An associative interchange mechanism is proposed for the substitution process. Thermodynamic parameters calculated from the temperature dependence of the outer sphere association equilibrium constants give negative ΔG ⁰ values for all the systems studied at all the temperatures (ΔH ⁰ = 30.05 ± 2.5, 18.9 ± 1.1 and 11.8 ± 0.2 kJ mol⁻¹; ΔS ⁰ = 123 ± 8, 94 ± 3 and 74 ± 1 J K⁻¹ mol⁻¹ for L¹H, L²H and L³H, respectively), which also support our proposition.     

Oxygen excess nonstoichiometry and thermodynamic quantities of La2NiO4?+?δ

The oxygen excess nonstoichiometry of La₂NiO_4 + δ is measured as a function of temperature and oxygen partial pressure (pO₂) by coulometric titration method. A positive deviation from the ideal dilution solution behavior is exhibited, and the partial molar thermodynamic quantities of La₂NiO_4 + δ are calculated from the Gibbs–Helmholtz equation for regular solution by introducing the activity coefficient of the charge carriers. The activity coefficient of holes is successfully calculated by using the Joyce–Dixon approximation of the Fermi–Dirac integral. The effective mass of holes ( m_\texth^* m_{\text{h}}^{{*}} ) is 1.27–1.29 times the rest mass (m _h), which indicate the action of band-like conduction and allow the effect of the small degree of polaron hopping to be ignored. The activity coefficient of holes calculated against the oxygen nonstoichiometry clearly illustrates the early positive deviation of the activity coefficient of holes from unit, leading to g_{\texth ^·} \gamma_{{{\text{h}}^{ \bullet }}}  ≈ 14 at δ ≈ 0.08, which is quite close to the literature value of g_{\texth ^·} \gamma_{{{\text{h}}^{ \bullet }}}  ≈ 10 at δ ≈ 0.08. All the evaluated thermodynamic quantities are in good agreement with the experimental literature values.     

Individual extraction constants of some divalent metal cations in the two-phase water-phenyltrifluoromethyl sulfone system

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium \textM ²⁺ ( \textaq ) + \textSr ²⁺ ( \textorg ) ? \textM ²⁺ ( \textorg ) + \text Sr ²⁺ ( \textaq ) {\text{M}}^{ 2+ } \left( {\text{aq}} \right) + {\text{Sr}}^{ 2+ } \left( {\text{org}} \right) \Leftrightarrow {\text{M}}^{ 2+ } \left( {\text{org}} \right) + {\text{ Sr}}^{ 2+ } \left( {\text{aq}} \right) taking place in the two-phase water–phenyltrifluoromethyl sulfone (abbrev. FS 13) system (M²⁺ = Mg²⁺, Ca²⁺, Ba²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, \textUO₂^{2 +} {\text{UO}}_{2}^{2 + } , Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺; aq = aqueous phase, org = FS 13 phase) were evaluated. Furthermore, the individual extraction constants of the M²⁺ cations in this two-phase system were calculated; they were found to increase in the series of Mg²⁺, \textUO₂^{2 +} {\text{UO}}_{2}^{2 + }  < Ca²⁺, Co²⁺ < Cd²⁺, Ni²⁺ < Zn²⁺ < Cu²⁺, Mn²⁺, Fe²⁺ < Pb²⁺ < Ba²⁺.     

Differentiation of α- or β-Aspartic Isomers in the Heptapeptides by the Fragments of [M + Na]<Superscript>+</Superscript> Using Ion Trap Tandem Mass Spectrometry

Electrospray ionization coupled with low energy collision induced dissociation (CID) in an ion trap mass spectrometer was used to examine the fragmentation patterns of the [M + Na]⁺ of eight pairs of heptapeptides containing α- or β-Asp residues in second and sixth amino acid positions, respectively. Selective cleavages at the peptide backbone C-terminal to two Asp residues were observed, which generated a series of C-terminal y₅ ions and N-terminal b₆ ions. Two typical ions: [ \texty₅ + \textNa-\textH ] ⁺ {\left[ {{{\text{y}}_{{5}}} + {\text{Na}}-{\text{H}}} \right]^{ + }} and [ \textb₆ + \textNa + \textOH ] ⁺ {\left[ {{{\text{b}}_{{6}}} + {\text{Na}} + {\text{OH}}} \right]^{ + }} , produced by α-Asp containing peptides were noted to be much more abundant than those of the peptides with β-Asp, which could be used for distinction of the isomers in Asp2 and Asp6, respectively. In addition, a series of internal ions generated by simultaneous cleavages at Asp residues were detected. Competitive reactions of carboxylic groups occurred between Asp6 side chain and C-terminus. Formation mechanisms of most product ions are proposed. The results obtained in this work are significant since low energy CID has been demonstrated to be effective for the distinction of Asp isomers.     

Thermochemical properties of two nitrothiophene derivatives

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 ( \textg ), {{\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 ( \textcr ) , {{\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.     

Electrochemical impedance study of hydrogen evolution on Bi(001) electrode in the HClO4 aqueous solutions

Electrochemical impedance spectroscopy has been applied for investigation of the hydrogen evolution kinetics at the electrochemically polished Bi(001) plane, and the complicated reaction mechanism (slow adsorption and charge-transfer steps) has been established. The charge-transfer resistance and adsorption capacitance values depend noticeably on the electrode potential applied. The adsorption resistance is maximal in the region of electrode potential E _min = −0.65 V vs. (Hg|Hg₂Cl₂|4 M KCl), where the minimal values of constant phase element (CPE) coefficient Q have been calculated. The fractional exponent α _CPE values of the CPE close to unity (α _CPE ≥ 0.94 and weakly dependent on the electrode potential and pH of solution () have been obtained, indicating the weak deviation of Bi(001)|HClO₄ + H₂O interface from the ideally flat capacitive electrode. Q differs only very slightly from double-layer capacitance C _dl values in the whole region of potentials and , investigated.     

Mechanisms for the formation of layered A<Subscript>4</Subscript>B<Subscript>3</Subscript>O<Subscript>12</Subscript> compounds from coprecipitated hydroxocarbonate and hydroxide systems

We have established and analyzed the sequences of phase transitions in synthesis of layered compounds in the A_nB_n–1O_3n family ( \textA₃^\textII\textLnB₃^\textV\textO₁₂ {\text{A}}_3^{\text{II}}{\text{LnB}}_3^{\text{V}}{{\text{O}}_{{12}}} (A^II = Ba, Sr, Ln = La, Nd, B^V = Nb, Ta) and La₄Ti₃O₁₂ with n = 4) from coprecipitated hydroxocarbonate and hydroxide systems, including steps involving the formation, solid-phase reaction, or structural rearrangement of intermediates.     

Oxidation of 3-(4-methoxyphenoxy)-1,2-propanediol by bis(hydrogen periodato)argentate(III) complex anion: a kinetic study

Oxidation of 3-(4-methoxyphenoxy)-1,2-propanediol (MPPD) by bis(hydrogenperiodato) argentate(III) complex anion, [Ag(HIO₆)₂]⁵⁻ has been studied in aqueous alkaline medium by use of conventional spectrophotometry. The major oxidation product of MPPD has been identified as 3-(4-methoxyphenoxy)-2-ketone-1-propanol by mass spectrometry. The reaction shows overall second-order kinetics, being first-order in both [Ag(III)] and [MPPD]. The effects of [OH⁻] and periodate concentration on the observed second-order rate constants k′ have been analyzed, and accordingly an empirical expression has been deduced:

Nickel surface anodic oxidation and electrocatalysis of oxygen evolution

The processes of nickel surface anodic oxidation taking place within the range of potentials preceding oxygen evolution reaction (OER) in the solutions of 1 M KOH, 0.5 M K₂SO₄, and 0.5 M H₂SO₄ have been analyzed in the present paper. Metallic nickel, thermally oxidized nickel, and black nickel coating were used as Ni electrodes. The methods of cyclic voltammetry and X-ray photoelectron spectroscopy were employed. The study was undertaken with a view to find the evidence of peroxide-type nickel surface compounds formation in the course of OER on the Ni electrode surface. On the basis of experimental results and literature data, it has been suggested that in alkaline solution at E ≈ 1.5 V (RHE) reversible electrochemical formation of Ni(IV) peroxide takes place according to the reaction as follows: This reaction accounts for both the underpotential (with respect to ) formation of O₂ from NiOO₂ peroxide and also small experimental values of dE/dlgi slope (<60 mV) at low anodic current densities, which are characteristic for the two-electron transfer process. It has been inferred that the composition of the γ-NiOOH phase, indicated in the Bode and revised Pourbaix diagrams, should be ∼5/6 NiOOH + ∼1/6 NiOO₂. The schemes demonstrating potential-dependent transitions between Ni surface oxygen compounds are presented, and the electrocatalytic mechanisms of OER in alkaline, acid, and neutral medium have been proposed.     

Determination of thermodynamic properties of YRhO3(s) by solid-state electrochemical cell and differential scanning calorimeter

The standard molar Gibbs free energy of formation of YRhO₃(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: ( - )\textPt - Rh/{ \textY₂\textO_\text3( \texts ) + \textYRh\textO₃( \texts ) + \textRh( \texts ) }//\textCSZ//\textO₂( p( \textO₂ ) = 21.21  \textkPa )/\textPt - 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 YRhO₃(s) from elements in their standard state using this electrochemical cell has been calculated and can be represented by: D_\textfG^\texto{ \textYRh\textO₃( \texts ) }/\textkJ  \textmo\textl ^{- 1}( ±1.61 ) = - 1,147.4 + 0.2815  T  ( \textK ) {\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 C^o_p,m C^{o}_{{p,m}} (T) of YRhO₃(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 YRhO₃(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.     

Standard enthalpies of formation of Li,Na, K,and Cs thiolates

The standard enthalpies of formation of alkaline metals thiolates in the crystalline state were determined by reaction-solution calorimetry. The obtained results at 298.15 K were as follows: \Updelta_\textf H_\textm^\texto (\textMSR,  \textcr) \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} ({\text{MSR,}}\;{\text{cr}}) /kJ mol⁻¹ = −259.0 ± 1.6 (LiSC₂H₅), −199.9 ± 1.8 (NaSC₂H₅), −254.9 ± 2.4 (NaSC₄H₉), −240.6 ± 1.9 (KSC₂H₅), −235.8 ± 2.0 (CsSC₂H₅). These results where compared with the literature values for the corresponding alkoxides and together with values for \Updelta_\textf H_\textm^\texto ( \textMSH,  \textcr) \Updelta_{\text{f}} H_{\text{m}}^{\text{o}} \left( {{\text{MSH}},\;{\text{cr}}}\right) were used to derive a consistent set of lattice energies for MSR compounds based on the Kapustinskii equation. This allows the estimation of the enthalpy of formation for some non-measured thiolates.