Physico-chemical Investigation of Mixed Micelle Formation Between Tetradecyltrimethylammonium Bromide and Dodecyltrimethylammonium Chloride in Water and Aqueous Solutions of Sodium Chloride

Conductometric measurements have been employed to gain a detailed insight into the interactions between two cationic surfactants, tetradecyltrimethylammonium bromide (TTAB) and dodecyltrimethylammonium chloride (DTAC), in water and in an aqueous solution of sodium chloride. The experimental data were analyzed according to Rubingh’s model within the framework of the pseudophase separation model. The evaluated values of critical micelle concentration (cmc) were found to be lower than their corresponding cmc ^id values, signifying attractive interactions involving both components in the solutions. The micellar mole fractions (\( X_{1}^{\text{Rub}} \)) of TTAB evaluated by Rubingh’s model were always larger than the ideal values (\( X_{1}^{\text{id}} \)), signifying the higher involvement of TTAB in mixed micelles of TTAB and DTAC. Activity coefficients (\( f_{ 1}^{\text{Rub}} \) and \( f_{ 2}^{\text{Rub}} \)) were always below one in all cases signifying synergism in the mixed micelles. All the outcomes point to synergism and attractive interactions in the mixed systems. Values of excess Gibbs energy were evaluated by employing Rubingh’s model (\( \Delta G_{\text{ex}}^{\text{Rub}} \)) and the \( \Delta G_{\text{ex}}^{\text{Rub}} \) values obtained are negative. The values of \( \Delta H_{\text{m}}^{\text{o}} \) and \( \Delta S_{\text{m}}^{\text{o}} \) reveal that hydrophobic interaction is expected to be the binding force between TTAB and DTAC in aqueous media at lower temperatures, while both hydrophobic interactions as well as exothermic interactions are involved at higher temperatures. The interaction forces between the surfactants were found to be enhanced in the presence of NaCl.     

Lego-like spheres and tori

Given a connected surface \({\mathbb {F}}^2\) with Euler characteristic \(\chi \) and three integers \(b>a\ge 1<k\), an \((\{a,b\};k)\)-\({\mathbb {F}}^2\) is a \({\mathbb {F}}^2\)-embedded graph, having vertices of degree only k and only a- and b-gonal faces. The main case are (geometric) fullerenes (5, 6; 3)-\({\mathbb {S}}^2\). By \(p_a\), \(p_b\) we denote the number of a-gonal, b-gonal faces. Call an \((\{a,b\};k)\)-map lego-admissible if either \(\frac{p_b}{p_a}\), or \(\frac{p_a}{p_b}\) is integer. Call it lego-like if it is either \(ab^f\)-lego map, or \(a^fb\)-lego map, i.e., the face-set is partitioned into \(\min (p_a,p_b)\) isomorphic clusters, legos, consisting either one a-gon and \(f=\frac{p_b}{p_a}\,b\)-gons, or, respectively, \(f=\frac{p_a}{p_b}\,a\)-gons and one b-gon; the case \(f=1\) we denote also by ab. Call a \((\{a,b\};k)\)-map elliptic, parabolic or hyperbolic if the curvature \(\kappa _b=1+\frac{b}{k}-\frac{b}{2}\) of b-gons is positive, zero or negative, respectively. There are 14 lego-like elliptic \((\{a,b\};k)\)-\({\mathbb {S}}^2\) with \((a,b)\ne (1,2)\). No \((\{1,3\};6)\)-\({\mathbb {S}}^2\) is lego-admissible. For other 7 families of parabolic \((\{a,b\};k)\)-\({\mathbb {S}}^2\), each lego-admissible sphere with \(p_a\le p_b\) is \(a^fb\) and an infinity (by Goldberg–Coxeter operation) of \(ab^f\)-spheres exist. The number of hyperbolic \(ab^f\,(\{a,b\};k)\)-\({\mathbb {S}}^2\) with \((a,b)\ne (1,3)\) is finite. Such \(a^f b\)-spheres with \(a\ge 3\) have \((a,k)=(3,4),(3,5),(4,3),(5,3)\) or (3, 3); their number is finite for each b, but infinite for each of 5 cases (a, k). Any lego-admissible \((\{a,b\};k)\)-\({\mathbb {S}}^2\) with \(p_b=2\le a\) is \(a^f b\). We list, explicitly or by parameters, lego-admissible \((\{a,b\};k)\)-maps among: hyperbolic spheres, spheres with \(a\in \{1,2\}\), spheres with \(p_b\in \{2,\frac{p_a}{2}\}\), Goldberg–Coxeter’s spheres and \((\{a,b\};k)\)-tori. We present extensive computer search of lego-like spheres: 7 parabolic (\(p_b\)-dependent) families, basic examples of all 5 hyperbolic \(a^fb\) (b-dependent) families with \(a\ge 3\), and lego-like \((\{a,b\};3)\)-tori.     

Thermochemical Properties of Dissolution of Nicotinic Acid C<Subscript>6</Subscript>H<Subscript>5</Subscript>NO<Subscript>2</Subscript>(s) in Aqueous Solution

Nicotinic acid (also known as niacin) was recrystallized from anhydrous ethanol. X-ray crystallography was applied to characterize its crystal structure. The crystal belongs to the monoclinic system, space group P2₍₁₎/c. The crystal cell parameters are a = 0.71401(4) nm, b = 1.16195(7) nm, c = 0.71974(6) nm, α = 90°, β = 113.514(3)°, γ = 90° and Z = 4. Molar enthalpies of dissolution of the compound, at different molalities m/(mol·kg^?1) were measured with an isoperibol solution–reaction calorimeter at T = 298.15 K. The molar enthalpy of solution at infinite dilution was calculated, according to Pitzer’s electrolyte solution model and found to be \( \Delta_{\text{sol}} H_{m}^{\infty } = ( 2 7. 3 \pm 0. 2) \) kJ·mol^?1 and Pitzer’s parameters (\( \beta_{{\text{MX}}}^{{\text{(0)}L}} \), \( \beta_{{\text{MX}}}^{{\text{(1)}L}} \) and \( C_{{\text{MX}}}^{\phi L} \)) were obtained. The values of apparent relative molar enthalpies (\( {}^{\phi }L \)) and relative partial molar enthalpies (\( \overline{{L_{2} }} \) and \( \overline{{L_{1} }} \)) of the solute and the solvent at different molalities were derived from the experimental enthalpy of dissolution values of the compound. Also, the standard molar enthalpy of formation of the anion \( {\text{C}}_{ 6} {\text{H}}_{ 4} \text{NO}_{2}^{-} \) in aqueous solution was calculated to be \( {\Delta_{\text{f}}^{} H}_{\text{m}}^{\text{o}} ({\text{C}}_{ 6} {\text{H}}_{ 4} {\text{NO}}_{2}^{-} \text{,aq}) = - \left( {603.2 \pm 1.2} \right)\;{\text{kJ}}{\cdot}{\text{mol}}^{-1} \).     

Thermodynamic Properties of Ternary Ionic Liquid Mixture Containing a Common Ion: Excess Molar Volumes,Excess Isentropic Compressibilities,Excess Molar Enthalpies and Excess Heat Capacities

In the present investigations, the excess molar volumes, \( V_{ijk}^{\text{E}} \), excess isentropic compressibilities, \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), and excess heat capacities, \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \), for ternary 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (i) + 1-butyl-3-methylimidazolium tetrafluoroborate (j) + 1-ethyl-3-methylimidazolium tetrafluoroborate (k) mixture at (293.15, 298.15, 303.15 and 308.15) K and excess molar enthalpies, \( \left( {H^{\text{E}} } \right)_{ijk} \), of the same mixture at 298.15 K have been determined over entire composition range of x _i and x _j . Satisfactorily corrections for the excess properties \( V_{ijk}^{\text{E}} \), \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), \( \left( {H^{\text{E}} } \right)_{ijk} \) and \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \) have been obtained by fitting with the Redlich–Kister equation, and ternary adjustable parameters along with standard errors have also been estimated. The \( V_{ijk}^{\text{E}} \), \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), \( \left( {H^{\text{E}} } \right)_{ijk} \) and \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \) data have been further analyzed in terms of Graph Theory that deals with the topology of the molecules. It has also been observed that Graph Theory describes well \( V_{ijk}^{\text{E}} \), \( \left( {\kappa_{S}^{\text{E}} } \right)_{ijk} \), \( \left( {H^{\text{E}} } \right)_{ijk} \) and \( \left( {C_{p}^{\text{E}} } \right)_{ijk} \) values of the ternary mixture comprised of ionic liquids.     

Volumetric,Acoustic and Transport Properties of Metformin Hydrochloride Drug in Aqueous <Emphasis Type="SmallCaps">d</Emphasis>-Glucose Solutions at <Emphasis Type="Italic">T</Emphasis> = (298.15–318.15) K

Apparent molar volumes, apparent molar adiabatic compressibilities and viscosity B-coefficients for metformin hydrochloride in aqueous d-glucose solutions were determined from solution densities, sound velocities and viscosities measured at T = (298.15–318.15) K and at pressure p = 101 kPa as a function of the metformin hydrochloride concentrations. The standard partial molar volumes (\( \phi_{V}^{0} \)) and slopes (\( S_{V}^{*} \)) obtained from the Masson equation were interpreted in terms of solute–solvent and solute–solute interactions, respectively. Solution viscosities were analyzed using the Jones–Dole equation and the viscosity A and B coefficients discussed in terms of solute–solute and solute–solvent interactions, respectively. Adiabatic compressibility (\( \beta_{s} \)) and apparent molar adiabatic compressibility (\( \phi_{\kappa }^{{}} \)), limiting apparent molar adiabatic compressibility (\( \phi_{\kappa }^{0} \)) and experimental slopes (\( S_{\kappa }^{*} \)) were determined from sound velocity data. The standard volume of transfer (\( \Delta_{t} \phi_{V}^{0} \)), viscosity B-coefficients of transfer (\( \Delta_{t} B \)) and limiting apparent molar adiabatic compressibility of transfer (\( \Delta_{t} \phi_{\kappa }^{0} \)) of metformin hydrochloride from water to aqueous glucose solutions were derived to understand various interactions in the ternary solutions. The activation parameters of viscous flow for the studied solutions were calculated using transition state theory. Hepler’s coefficient \( (d\phi /dT)_{p} \) indicated the structure making ability of metformin hydrochloride in the ternary solutions.     

Measurement and Calculation the Excess Molar Properties of Binary Mixtures Containing Isobutanol, 1-Amino-2-Propanol,and 1-Propanol at Temperatures of (293.15 to 333.15) K

Densities, ρ, and viscosities, η, of pure isobutanol, 1-amino-2-propanol, and 1-propanol, along with their binary mixtures of {x ₁isobutanol + x ₂1-propanol}, {x ₁1-amino-2-propanol + x ₂1-propanol}, and {x ₁1-amino-2-propanol + x ₂isobutanol} were measured over the entire composition range and at temperatures (293.15–333.15) K at ambient pressure (81.5 kPa). Excess molar properties such as the excess molar volume, V _m ^E , partial molar volumes, \( \bar{V}_{1} \) and \( \bar{V}_{2} \), excess partial molar volumes, \( \bar{V}_{1}^{\text{E}} \) and \( \bar{V}_{2}^{\text{E}} \), thermal expansion coefficient, α, excess thermal expansion coefficient, α ^E, viscosity deviation, Δη, and the excess Gibbs energy of activation, ?G ^E*, for the binary mixtures were calculated from the experimental values of densities and viscosities. The excess values of the binary mixtures are negative in the entire composition range and at all temperatures, and increase with increasing temperature. Viscosity deviations, Δη, are negative over the entire composition range and decrease with increasing temperature. The viscosities of the mixtures were correlated by the models of McAllister, Heric, Hind, Katti, and Nissan. The obtained data were correlated by Redlich–Kister equation and the fitting parameters and standard deviations were determined.     

Densities and Speeds of Sound of Binary Liquid Mixtures of 1,4-Butanediol with 2-Methoxyethanol and 2-Propoxyethanol at <Emphasis Type="Italic">T</Emphasis> = (303.15, 308.15, 313.15 and 318.15) K

Densities, ρ, and speeds of sound, u, for the binary liquid mixtures of 1,4-butanediol (1,4-BD) + 2-alkoxyethanols {2-methoxyethanol (2-ME), or 2-propoxyethanol (2-PE)} over the whole composition range have been measured at T = (303.15, 308.15, 313.15 and 318.15) K, and at atmospheric pressure (p = 0.1 kPa). Experimental data for the densities and speeds of sound have been used to derive the quantities like excess molar volume, \( V_{\text{m}}^{\text{E}} \), excess isentropic compressibility, \( \kappa_{S}^{\text{E}} \), excess molar isentropic compressibility, \( K_{{S,{\text{m}}}}^{\text{E}} \), excess speed of sound, \( u^{\text{E}} \), and excess isobaric thermal expansion \( \alpha_{p}^{\text{E}} \). These excess parameters were correlated by Redlich–Kister polynomials. Excess partial molar volumes (\( \bar{V}_{\text{m,1}}^{\text{E}} \) and \( \bar{V}_{\text{m,2}}^{\text{E}} \)) and their limiting values at infinite dilution (\( \bar{V}_{\text{m,1}}^{{ 0 {\text{E}}}} \) and \( {\bar{\text{V}}}_{\text{m,2}}^{{ 0 {\text{E}}}} \)) have been calculated from the experimental density measurements and were analytically obtained using the Redlich–Kister polynomials. The results are discussed in terms of intermolecular interactions and their dependence on composition and temperature.     

Densities,Ultrasonic Velocities,Excess Properties and IR Spectra of Binary Liquid Mixtures of Organic Esters (Ethyl Lactate,Some Organic Carbonates)

Organic esters of carbonic acid {dimethyl carbonate (DMC)/diethyl carbonate (DEC)/propylene carbonate (PC)}, in combination with a lactate ester {ethyl lactate (EL)}, with green chemistry characteristics were chosen for the present study of molecular interactions in binary liquid mixtures. Densities (ρ) and ultrasonic velocities (U) of the pure solvents and liquid mixtures were measured experimentally over the entire composition range at temperatures (303.15, 308.15, 313.15 and 318.15) K and atmospheric pressure. The experimental data was used to calculate thermodynamic and acoustic parameters \( V_{\text{m}}^{\text{E}} \), \( \kappa_{S}^{\text{E}} \), \( L_{\text{f}}^{\text{E}} \), \( \bar{V}_{\text{m,1}}^{{}} \), \( \bar{V}_{\text{m,2}}^{{}} \), \( \bar{V}_{\text{m,1}}^{\text{E}} \), \( \bar{V}_{\text{m,2}}^{\text{E}} \), \( \bar{V}_{ 1}^{\text{E,0}} \) and \( \bar{V}_{ 2}^{\text{E,0}} \) and the excess functions were fitted with the Redlich–Kister polynomial equation to obtain the binary solution coefficients and the standard deviations. It was observed that the values of \( V_{\text{m}}^{\text{E}} \), \( \kappa_{S}^{\text{E}} \) and \( L_{\text{f}}^{\text{E}} \) are positive for the mixtures of (EL + DMC/DEC) and negative for those of (EL + PC) over the entire range of composition and temperature. The positive values of \( V_{\text{m}}^{\text{E}} \), \( \kappa_{S}^{\text{E}} \) and \( L_{\text{f}}^{\text{E}} \) indicate the action of dispersion forces between the component molecules of (EL + DMC/DEC) mixtures whereas negative values for the mixture (EL + PC) suggest the existence of strong specific interactions between the component molecules, probably resulting from chemical and structural contributions. The excess properties have also been analyzed by using the reduced (\( Y^{\text{E}} /x_{1} x_{2} \)) excess function approach and the results are found to be in agreement with those from the corresponding \( Y^{\text{E}} \)(= \( V_{\text{m}}^{\text{E}} \), \( \kappa_{S}^{\text{E}} \) and \( L_{\text{f}}^{\text{E}} \)) values. This is further supported by FTIR spectral analysis.     

A Thermodynamic and Physical Study on (1-Hexyl-3-methylimidazolium Chloride + 1-Pentanol and Ethylene Glycol) Binary Mixtures at Temperatures (293.15–333.15) K

Densities, ρ, viscosities, η, and refractive indices, n _D, for 1-hexyl-3-methyl imidazolium chloride ([hmim]Cl) (IL), 1-pentanol, and ethylene glycol (EG), and for the binary mixtures {x ₁[hmim]Cl + x ₂1-pentanol} and {x ₁[hmim]Cl + x ₂EG} were measured over the entire composition range at temperatures (293.15–333.15) K and ambient pressure. The excess molar volumes, \( V_{\text{m}}^{\text{E}} \), and viscosity deviations, Δη, for the binary mixtures were calculated from the experimental data. The \( V_{\text{m}}^{\text{E}} \) values of {x ₁[hmim]Cl + x ₂1-pentanol} mixtures are negative over the entire composition range at all temperatures, and increase with increasing temperature in the alcohol rich region and decrease with increasing temperature in the IL rich range. The \( V_{\text{m}}^{\text{E}} \) values of {x ₁[hmim]Cl + x ₂EG} mixture are positive in the alcohol rich range and negative in the IL rich range at all temperatures, and decrease with increasing temperature. Viscosity deviations of both mixtures are negative over the entire composition range at all temperatures and decrease with increasing temperature. The excess molar properties were correlated by Redlich–Kister equation, and the excess molar volumes were correlated using the PFP model. The fitting parameters and standard deviations were determined.     

Solvent extraction of calcium and strontium into nitrobenzene by using synergistic mixture of hydrogen dicarbollylcobaltate and diphenyl-<Emphasis Type="Italic">N</Emphasis>-butylcarbamoylmethyl phosphine oxide

Extraction of microamounts of calcium and strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H⁺B^?) in the presence of diphenyl-N-butylcarbamoylmethyl phosphine oxide (DPBCMPO, L) has been investigated. The equilibrium data have been explained assuming that the species HL⁺, \( {\text{HL}}_{2}^{ + } \), \( {\text{ML}}_{2}^{2 + } \), \( {\text{ML}}_{3}^{2 + } \) and \( {\text{ML}}_{4}^{2 + } \) (M²⁺ = Ca²⁺, Sr²⁺) 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 of the \( {\text{SrL}}_{2,{\text{org}}}^{2 + } \) complex is somewhat higher than that of species \( {\text{CaL}}_{2,{\text{org}}}^{2 + } \), while the stability constants of the remaining strontium complexes \( {\text{SrL}}_{3,{\text{org}}}^{2 + } \) and \( {\text{SrL}}_{4,{\text{org}}}^{2 + } \) are smaller than those of the corresponding complex species \( {\text{CaL}}_{n}^{2 + } \) (n = 3, 4).     

Binary self-similar chemical structures

The recursive series \(f_{n+1} =l\cdot f_n +m\cdot f_{n-1} \) (l, m = 1,2,3...) defines the generators of a chain of components L and S, \(\left\{ {\begin{array}{l} L\rightarrow \underbrace{LL{\ldots }L}_l\underbrace{SS{\ldots }S}_m \\ S\rightarrow L \\ \end{array}} \right\} \), such that L and S have a geometric dimension equal to \(d = 0, 1, 2, 3,{\ldots }\). If L, S are the atoms of two different elements A, B (dimension \(d = 0\)) or two self-similar structures with \(d > 0\) that are composed of these elements, then such a generator forms a self-similar binary structure with the dimension \(d+1\) (a quasicrystal), composed of \(\hbox {A}_{x^{\prime }}\hbox {B}\), where \(x^{\prime }\) depends solely on the parameters l and m. In this study, the stoichiometric coefficient \(x^{\prime }\) was calculated for about 20 of such quasicrystals. The generator was found to enable, for certain values of l and m, the formation of structures with degenerate symmetry, that is, the transition from self-similar to translational symmetry. Thus, the generated structures can be divided according to l and m into three groups: structures that contain only one type of homobonds, A–A, with self-similarity as the only permissible symmetry; structures that at least sometimes contain both types of homobonds, A–A and B–B, with self-similarity as the only permissible symmetry; and structures that sometimes show translational symmetry. All of the researched structures in the first group have the same estimated values of internal energy and configuration entropy determined by the isotopic composition. All structures in the second group have the same configuration entropy but different internal energies. In the third group, the configuration entropy of structures that show translational symmetry is lower than that of the self-similar structures. On the other hand, internal energy favours (that is, is lower in) structures with translational symmetry over self-similar structures only when the energy of the A–B bonds is higher than the mean energy of A–A and B–B bonds. In other words, self-similar systems can be energetically more stable compared to crystals as long as the energy of the A–B heterobonds is low. The method for generating self-similar objects proposed in this paper seems to be the first method in which the means of generation do not change with the geometric dimension d of the generated structure.     

Measurement and Modeling the Excess Molar Volumes and Refractive Index Deviations of Binary Mixtures of 2-Propanol, 2-Butanol and 2-Pentanol with <Emphasis Type="Italic">N</Emphasis>-Propylamine

The densities, ρ, and refractive indices, n _D, of 2-alkanols (C₃–C₅) with N-propylamine have been measured for the whole range of composition at temperatures from (298.15–328.15) K at 10 K intervals and ambient pressure of 81.5 kPa, using an Anton Paar DMA 4500 oscillating tube densimeter and an Anton Paar Abbemat 500 automatic refractometer. From the experimental data, excess molar volumes \( V_{\text{m}}^{\text{E}} \) partial molar volumes \( \bar{V}_{i} \) apparent molar volumes V _?i and refractive index deviations Δn _D the binary systems consisting of N-propylamine + 2-alkanols (2-propanol, 2-butanol, 2-pentanol) were calculated and \( V_{\text{m}}^{\text{E}} \) and Δn _D values were correlated with the Redlich–Kister polynomial. The effect of temperature and the chain length of the alcohol on the excess molar volumes and refractive index deviations are discussed in terms of molecular interaction between unlike molecules. The excess molar volumes are negative and refractive index deviations are positive over the entire composition range, which indicates strong hydrogen bonding between molecules of the mixtures. A comparative study has been made of the refractive indices obtained experimentally and those calculated by means of the Lorentz–Lorenz, Weiner and Arago–Biot relations. The perturbed chain statistical associating fluid theory (PC-SAFT), simplified PC-SAFT and Prigogine–Flory–Patterson theory were also applied to correlate and predict the density and excess molar volumes of the mixtures.     

Kinetics and mechanism of base hydrolysis of tris(3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine)iron(II) in aqueous and micellar media

The kinetics of base hydrolysis of tris(3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine)iron(II), \( {\text{Fe(PDT)}}_{ 3}^{2 + } \) has been studied in aqueous, cetyltrimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) media at 25, 35 and 45 °C under pseudo-first-order conditions, i.e. \( [ {\text{OH}}^{ - } ]\gg [{\text{Fe(PDT)}}_{ 3}^{2 + } ] \). The reactions are first order in both of substrate \( {\text{Fe(PDT)}}_{ 3}^{2 + } \) and hydroxide ion. The rates decrease with increasing ionic strength in aqueous and CTAB media, whereas SDS medium shows little ionic strength effect. The rate also increases with CTAB concentration but decreases with SDS. The specific rate constant, k and thermodynamic parameters (E _a, ΔH ^#, ΔS ^# and ΔG ^#) have also been evaluated. The near equal values of ΔG ^# obtained in aqueous and CTAB media suggest that these reactions occur essentially by the same mechanism such that \( {\text{Fe(PDT)}}_{ 3}^{2 + } \) reacts with OH^? in the rate-determining step. The ionic strength effect in SDS medium suggests that the rate-determining step involves an ion and a neutral species. The results in this study are compared with those obtained for other iron(II)-bipyridine complexes.     

Analytical evaluation of zero-pressure Joule–Thomson coefficient using second virial coefficient and its application

In this paper, we present an analytical procedure to evaluate the zero-pressure Joule–Thomson coefficient using the second virial coefficient over the Lennard-Jones (12-6) potential. The analytical expressions are derived for the first and second derivatives of the second virial coefficient. The proposed formulae guarantee the accurate and fast calculation of the Joule–Thomson coefficient. As an example of application, the analytical expression obtained is used to calculate results for the molecules He, Xe, \(N_2 \), \(H_2 \), \(O_2 \), \({\textit{CO}}\), \(C_2 H_4 \), \(C_3 H_8 \) and \(C_5 H_{12} \). The results obtained by the present analytical expression are found to be in good agreement with the data in the literature. The calculation of results will help to estimate the Joule–Thomson coefficient with sufficient reliability and to determine the interaction potentials.     

Transition-metal dichalcogenide heterostructure solar cells: a numerical study

We evaluate the tunneling short-circuit current density \(J_{TU}\) in a p–i–n solar cell in which the transition metal dichalcogenide heterostructure (\(\hbox {MoS}_2/\hbox {WS}_2\) superlattice) is embedded in the intrinsic i region. The effects of varying well and barrier widths, Fermi energy levels and number of quantum wells in the i region on \(J_{TU}\) are examined. A similar analysis is performed for the thermionic current \(J_{TH}\) that arises due to the escape and recapture of charge carriers between adjacent potential wells in the i-region. The interplay between \(J_{TU}\) and \(J_{TH}\) in the temperature range (300–330 K) is examined. The thermionic current is seen to exceed the tunneling current considerably at temperatures beyond 310 K, a desirable attribute in heterostructure solar cells. This work demonstrates the versatility of monolayer transition metal dichalcogenides when utilized as fabrication materials for van der Waals heterostructure solar cells.     

Interaction of a Surface-Active Ionic Liquid with an Antidepressant Drug: Micellization and Spectroscopic Studies

The interaction of the antidepressant drug nortriptyline hydrochloride (NOT) with the surface-active ionic liquid (SAIL), 1-decyl-3-methylimidazolium chloride, [C₁₀mim][Cl], has been studied using multiple techniques, including conductometric titration, tensiometric, fluorometric, dynamic light scattering and UV–visible spectrophotometric measurements. There is a significant decrease in the cmc of SAIL on the addition of the drug NOT, indicating adsorption of drug molecules in the outer portion of the micelle. In the present study, the values of the packing parameter, P, lie in the range of 0–0.3, which suggests that the micelles formed are spherical in nature. More negative values of the standard Gibbs energy of adsorption, \( \Delta G_{\text{ad}}^{ \circ } \), compared to \( \Delta G_{\text{m}}^{ \circ } \) support our contention that adsorption of SAIL on the air-solution interface is relatively more favorable than its micellization in the presence of NOT. Fluorescence and DLS studies indicate that the aggregation number, N_agg, and hydrodynamic radius of SAIL increase with increase in concentration of NOT. The UV–visible spectroscopic study confirms the formation of a new complex between SAIL and NOT; this is also supported by the negative Gibbs energy of complexation.     

Basicity of isomeric ditetrazolylbenzenes and their <Emphasis Type="Italic">N-tert</Emphasis>-butyl derivatives

The basicity constants \((pK_{BH^ + } ,pK_{BH^{2 + } } )\) of 1,2-, 1,3-, and 1,4-bis(tetrazol-5-yl)benzenes and their N-tert-butyl derivatives in aqueous sulfuric acid and the dissociation constants (pK _HB) of the corresponding H-complexes with p-fluorophenol in carbon tetrachloride were determined by UV and IR spectroscopy. Mono-and diprotonation of isomeric ditetrazolylbenzenes is observed in the acidity range (H ₀) from ?1 to ?5 (\(pK_{BH^ + } \) ?2.5 to ?3.0; \(pK_{BH^{2 + } } \) ?3.8 to ?4.9). Introduction of a tert-butyl group into the 2-position of the heteroring almost does not affect the basicity of ditetrazolyl benzenes. Among the examined compounds, 1,2-bis(2-tert-butyltetrazol-5-yl)benzene is the strongest proton acceptor with respect to p-fluorophenol as standard proton donor, presumably due to formation of a complex with bifurcated (three-center) hydrogen bond.     

Synthesis,characterization, crystal structure and cytotoxicity of 2,4-bis(selenomethyl)quinazoline

Organoselenium compounds have already been reported to be good anticarcinogenic candidates. A new selenoquinazoline derivative, 2,4-bis(selenomethyl)quinazoline (compound 1), has been synthesized, spectroscopically characterized and its crystal structure has been studied. An intermolecular coupling between C₂ and \( {\text{H}}_{5}^{\prime } \) in the Heteronuclear Multiple Bond Correlation (HMBC) experiment has been observed. Assuming that the head-to-tail overlap of parallel molecules (as identified by X-ray diffraction) remains in solution to give bimolecular entities, the π–π interaction enables heteronuclear coupling between the former atoms with a three-bond distance [C₂···(π–π)···\( {\text{C}}_{5}^{\prime } \)–\( {\text{H}}_{5}^{\prime } \)]. The crystal structure of compound 1 has been solved by X-ray diffraction. It crystallizes in triclinic system, space group P?1. Unit cell parameters are a = 7.4969(7) Å, b = 8.7008(8) Å, c = 10.1666(9) Å, α = 110.215(2)°, β = 90.354(2)°, γ = 115.017(1)°. Linear chains in crystals of compound 1 are generated by C–H···Se and Se···Se bonds between molecules. Furthermore, head-to-tail overlap of parallel molecules, in which π–π interactions can occur, is observed. Compound 1 exhibited a cytotoxic effect in all of the evaluated tumoral cell lines and showed a higher cytotoxic effect in colon and breast cancer cell lines than etoposide, which was used as a reference compound.     

The Partial Molar Isothermal Compressions of the Nucleosides Adenosine,Cytidine, and Uridine in Aqueous Solution at <Emphasis Type="Italic">T</Emphasis> = (288.15 and 313.15) K

Sound speeds have been measured for aqueous solutions of the nucleosides adenosine, cytidine, and uridine at T = (288.15 and 313.15) K and at ambient pressure. The partial molar isentropic compressions at infinite dilution, \( K_{S,2}^{\text{o}} \), were derived from the speed of sound data. The partial molar heat capacities at infinite dilution, \( C_{p,2}^{\text{o}} \), for the three nucleosides at T = (288.15 and 313.15) K were also determined. These \( K_{S,2}^{\text{o}} \) and \( C_{p,2}^{\text{o}} \) results, along with partial molar isobaric expansions at infinite dilution, \( E_{2}^{\text{o}} = \, (\partial V_{2}^{\text{o}} /\partial T)_{p} \), that were derived using data from the literature, were used to evaluate the partial molar isothermal compressions at infinite dilution, \( K_{T,2}^{\text{o}} \{ K_{T,2}^{\text{o}} = - \, (\partial V_{2}^{\text{o}} /\partial p)_{T} \} \), for the nucleosides. The \( K_{T,2}^{\text{o}} \) results were rationalized in terms of nucleoside hydration and its temperature dependence.     

Synthesis,crystal structure,and thermodynamics of a high-nitrogen copper complex with <Emphasis Type="Italic">N</Emphasis>, <Emphasis Type="Italic">N</Emphasis>-bis-(1(2)H-tetrazol-5-yl) amine

A new high-nitrogen complex [Cu(Hbta)₂]·4H₂O (H₂bta = N,N-bis-(1(2)H-tetrazol-5-yl) amine) was synthesized and characterized by elemental analysis, single crystal X-ray diffraction and thermogravimetric analyses. X-ray structural analyses revealed that the crystal was monoclinic, space group P2(1)/c with lattice parameters a = 14.695(3) Å, b = 6.975(2) Å, c = 18.807(3) Å, β = 126.603(1)°, Z = 4, D _c = 1.888 g cm^?3, and F(000) = 892. The complex exhibits a 3D supermolecular structure which is built up from 1D zigzag chains. The enthalpy change of the reaction of formation for the complex was determined by an RD496–III microcalorimeter at 25 °C with the value of ?47.905 ± 0.021 kJ mol^?1. In addition, the thermodynamics of the reaction of formation of the complex was investigated and the fundamental parameters k, E, n, \( \Updelta S_{ \ne }^{{{\uptheta}}} \), \( \Updelta H_{ \ne }^{{{\uptheta}}} \), and \( \Updelta G_{ \ne }^{{{\uptheta}}} \) were obtained. The effects of the complex on the thermal decomposition behaviors of the main component of solid propellant (HMX and RDX) indicated that the complex possessed good performance for HMX and RDX.