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  • 1
    Electronic Resource
    Electronic Resource
    Apparent molar heat capacities and volumes, van der Waals volumes and accessible surface areas of alkylated derivatives of cytosine and uracil in aqueous solutions at 25°C. (1993)
    Springer
    Journal of solution chemistry 22 (1993), S. 907-918 
    Details
    ISSN: 1572-8927
    Keywords: Nucleic acid bases ; uracil ; cytosine ; apparent molar heat capacities ; apparent molar volumes ; van der Waals volumes ; accessible surface areas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Densities and specific heat capacities of aqueous solutions: 1,3,5,6-tetramethyluracil, 1,6-dimethyl-3-ethyluracil, 1,6-dimethyl-3-propyluracil, 1,6-dimethyl-3-butyluracil, 1,N4-trimethylcytosine, 1,N4-dimethyl-5-ethylcytosine, 1,N4 dimethyl-5-propylcytosine, 1,N4-dimethyl-5-butylcytosine were determined using flow calorimetry and flow densimetry at 25°C. Apparent molar volumes and heat capacities, van der Waals volumes and accessible surface areas were determined. It was stated that for alkylcytosines and alkyluracils partial molar volumes and heat capacities correlate linearly with the number of substituted methylene groups-CH2-as well as with the van der Waals volumes and accessible surface areas of the compounds studied; for cyclooligouracils the cyclization effect was discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00646602
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  • 2
    Electronic Resource
    Electronic Resource
    Apparent molar volumes, heat capacities, and molecular excluded volumes of methylated, hydroxy and methoxy derivatives of 1-methylcytosine in aqueous solutions at 25°C (1996)
    Springer
    Journal of solution chemistry 25 (1996), S. 529-539 
    Details
    ISSN: 1572-8927
    Keywords: Derivatives of cytosine ; apparent molar heat capacities ; apparent molar volumes ; molecular excluded volumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Densities and specific heat capacities of aqueous solutions: 1-methylcytosine; 1-methyl-N4-hydroxycytosine; 1,5-dimethylcytosine; I,N4-dimethylcytosine; 1,5-dimethyl-N4-hydroxycytosine; 1-methyl-N4-methoxycytosine; 1,N4,N4-trimethylcytosine, 1,5-dimethyl-N4-methoxycytosine were determined using flow calorimetry and flow densimetry at 25°C. Apparent molar volumes and heat capacities were then determined. Molecular excluded volumes were evaluated. A relationship was found between the values of the increments in partial molar values and the kind of groups substituted. Four types of contributions were distinguished: substitution of hydrogen on C, N, and O (in OH group on N4) atoms by CH3 group and replacement of hydrogen on N4 atom by OH group. The correlation between the experimental partial molar volumes and calculated molecular excluded volumes was also elaborated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00973083
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  • 3
    Electronic Resource
    Electronic Resource
    Molecular Interactions of Macrocycles with Dipeptides in Aqueous Solutions. Partial Molar Volumes and Heat Capacities of Transfer of a Chiral 18-Crown-6 and of a Calix[4]resorcinarene Derivative from Water to Aqueous Dipeptide Solutions at 25°C (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 121-134 
    Details
    ISSN: 1572-8927
    Keywords: Partial molar volumes ; partial molar heat capacities ; D-α-manno-naphtho-18-crown-6-ether ; calix[4]resorcinarene ; Peptides: Ala–Ala, Ala–Glu, Ala-Ser, Ser-Leu
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Densities and specific heat capacities of ternary aqueous systems containing a dipeptide (alanyl-alanine, alanyl-glutamic acid, alanyl-serine or L-seryl-L-leucine) and a macrocycle (D-α-manno-naphtho-18-crown-6-ether or 2,8,14,20-tetrakis[-methyl (aminoformyl)]-4,6,10,12,16,18,22,24-octahydroxycalix[4]arene) were determined at 25°C by flow densimetry and flow calorimetry. The partial molar volume and heat capacity of transfer of a macrocycle from water to the dipeptide solution was determined as a function of the dipeptide concentration. Positive values for transfer volumes and transfer heat capacities are observed with all the solutions studied. With the crown ether, except for alanyl-glutamic acid where a 1:1 complex is clearly evidenced due to specific interactions of the side-chain functional group of the peptide with the crown ether, no stoichiometric complexes are confirmed and the partial molar quantities of transfer increase with the hydrophobic character of the dipeptide. Partial quantities of transfer are smaller with the calixarene than with the crown ether and stoichiometric complexes [calixarene]/[dipeptide] from 2:1 to 1:4 are evidenced, depending on the nature and the concentration of the dipeptide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022653222581
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  • 4
    Electronic Resource
    Electronic Resource
    Thermodynamic Properties of CTAB in Aqueous Solutions of Neutral Polymers at 25°C (1998)
    Springer
    Journal of thermal analysis and calorimetry 54 (1998), S. 271-278 
    Details
    ISSN: 1572-8943
    Keywords: heat capacities ; hexadecyltrimethylammonium bromide ; molar volumes ; polyethylene glycols ; polypropylene glycols ; surfactant-polymer interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Interactions of polyethylene glycols (PEGs) and polypropylene glycols (PPOs) in aqueous solutions of hexadecyltrimethylammonium bromide (CTAB) were investigated through thermodynamic properties at 25°C. The densities and heat capacities of the solutions were measured with a vibrating tube densimeter and a Picker flow microcalorimeter, respectively. The variations in the apparent molar volumes and heat capacities of both solutes, calculated from the densities and heat capacities of the solutions, are unusually large in the vicinity of the CMC, reflecting the existence of very strong interactions between CTAB and PPOs. With the more hydrophilic polymers, PEGs, the apparent properties of CTAB are less affected by the presence of the polymer, indicating that PEGs interact only weakly with CTAB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010162112407
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  • 5
    Electronic Resource
    Electronic Resource
    Excess heat capacities of ternary systems containing chlorobenzene or chloronaphthalene (1994)
    Springer
    Journal of solution chemistry 23 (1994), S. 307-323 
    Details
    ISSN: 1572-8927
    Keywords: Excess volumes and heat capacities ; ternary systems ; linear alkanes ; cyclohexane ; isooctane ; chlorobenzene ; 1-chloronaphthalene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Densities and heat capacities of ternary systems were determined at 25°C. The ternary systems consisted of: a polar molecule (component 1) + a mixture of alkanes (components 2 and 3) of different sizes and shapes. Five such systems were studied: chlorobenzene + cyclohexane + n-heptane; chlrobenzene + cyclohexane + n-hexadecane; chlorobenze + cyclohexane + isooctane; chlorobenzene + isooctane + n-heptane; 1-chloronaphthalene + isooctane + n-heptane. The excess molar volumes and heat capacities were obtained along dilution lines by component 1 (chlorobenzene or 1-chloronaphthalene) of mixtures of components 2 and 3 (at fixed component 2 mole fraction X2). Unexpectedly the excess heat capacities C p1(23) E of the pseudo-binaries {1+(2+3)} do not always fall between the two (limiting) curves of C p12 E and C p13 E corresponding to the two binaries {1+2} and {1+3}. Instead, especially for {chlorobenzene + cyclohexane + an n-alkane} the C p1(23) E curves are displaced toward less negative values, even beyond the limiting values corresponding to the binaries. This correlates semi-quantitatively with the negative C p23 E of the binary {2+3}.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00973552
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  • 6
    Electronic Resource
    Electronic Resource
    Molar heat capacities and volumes of transfer of cytosine, thymine, caffeine and 1,3-diethylthymine to aqueous solutions of glycyl-glycine and L-α-alanyl-L-α-alanine at 25°C (1995)
    Springer
    Journal of solution chemistry 24 (1995), S. 623-632 
    Details
    ISSN: 1572-8927
    Keywords: Partial molar heat capacity ; partial molar volume ; nucleic acid bases ; cytosine ; thymine ; 1,3-diethylthymine ; caffeine ; dipeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Densities and specific heat capacities of ternary aqueous systems containing dipeptides (glycyl-glycine or L-α-alanyl-L-α-alanine) and nucleic acid bases (cytosine or thymine) or their alkyl derivatives (1,3-diethylthymine or caffeine) were determined at 25°C by flow calorimetry and flow densimetry. The partial molar volumes and heat capacities of transfer at infinite dilution of the different nucleic acid bases from water to water+dipeptide solutions were obtained therefrom. Except for the case of the transfer of cytosine to aqueous glycyl-glycine solutions where a small positive dependence of the transfer quantities was observed with the dipeptide concentration, the values of the heat capacities of transfer were in general low, positive or negative, depending on the compensation of hydrophobic-hydrophilic interactions between the dipeptide and the base. The volumes of transfer of most of the bases are very small, within the limit of the experimental error.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00973230
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  • 7
    Electronic Resource
    Electronic Resource
    Apparent molar heat capacities and volumes of electrolytes and ions int-butanol-water mixtures (1989)
    Springer
    Journal of solution chemistry 18 (1989), S. 229-248 
    Details
    ISSN: 1572-8927
    Keywords: Apparent molar heat capacity ; apparent molar volume ; electrolytes ; ions ; tertiary butanol-water ; TPTB assumption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The apparent molar volumes Vϕ and heat capacities C p,ϕ of NaCl, LiCl, NaF, KI, NaBPh4 and Ph4PCl have been determined in solutions of H2O containing up to 40 mass% t-butyl alcohol (TBA) by flow densitometry and flow microcalorimetry. Combination of these results with literature data allows calculation of Vϕ and C p,ϕ for 16 ions in these mixtures using the assumption that ΔtXφ(Ph4P+) = ΔtXφ(BPh 4 − ) where X=V or C p and ΔtXφ is the change in Xϕ for a species on transfer from H2O to TBA-H2O mixtures. These are the first reported single ion values for C p,ϕ in a mixed solvent. While whole electrolyte volumes and heat capacities show relatively smooth changes with solvent composition, ΔtXφ(ion) exhibit two well-developed extrema at around 10 and 25 mass% TBA. The shape of the ΔtXφ(ion) curves shows considerable uniformity among the alkali metal cations and the halide ions but the extrema become more pronounced with increasing size among the tetraalkylammonium ions. These extrema are analogous to those observed in aqueous organic mixtures of surfactants and are probably indicative of microphase transitions in these strongly interacting solvent mixtures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00652986
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  • 8
    Electronic Resource
    Electronic Resource
    Apparent molar heat capacities and volumes of electrolytes and ions in acetonitrile-water mixtures (1990)
    Springer
    Journal of solution chemistry 19 (1990), S. 207-223 
    Details
    ISSN: 1572-8927
    Keywords: Apparent molar volume ; apparent molar heat capacity ; electrolytes ; ions ; acetonitrile-water mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Apparent molar volumes Vφ and heat capacities Cp,φ of NaCl, KCl, KNO3, AgNO3, KI, NaBPh4 and Ph4PCl have been measured in acetonitrile (AN)-water mixtures up to xAN=0.25 by flow densitometry and flow microcalorimetry. Limited data have also been obtained for NaF, LiCl and KBr up to x AN =0.15. Single ion volumes and heat capacities of transfer were obtained using the assumption ΔtXφ(PH4P+) = ΔtXφ(BPh4-) where X=V or C p and ΔtXφ is the change in Xφ for a species on transfer from H2O to AN-H2O mixtures. Volumes and heat capacities for simple salts show relatively little dependence on solvent composition. However, ΔtXφ for simple ions show more pronounced variations, exhibiting at least one extremum. These extrema are similar to but much less pronounced than those derived previously for ions in t-butanol-water mixtures. Surprisingly little correlation is found between the present data and other thermodynamic transfer functions. This is attributed to the predominance of ion-solvent over solvent-solvent interactions in AN-H2O solutions. ΔtVφ and ΔtCp,φ for the silver ion differ markedly from those of the alkali metal ions as a result of the well-known specific interaction between Ag+ and AN.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00650455
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