Absorption Lineshapes in Two-Dimensional Electron Spin Resonance and the Effects of Slow Motions in Complex Fluids

A methodology for obtaining pure absorption two-dimensional electron spin resonance spectra is presented for the case of large inhomogeneous broadening and/or slow motions. For slow motions, the spectra consist of “complex Lorentzians” superimposed with complex weighting factors, presenting a challenge to obtaining absorption spectra. It is shown how absorption-type spectra can be recovered for the two-pulse COSY and SECSY experiments in such cases. For three-pulse 2D ELDOR experiments, absorption lineshapes can be obtained for the autopeaks, whereas the cross peaks would be of mixed-mode character, in general. However, for practical cases the dispersive components in the cross peaks will be relatively small. Theoretical and experimental absorption spectra are provided to illustrate the method and to show the improved resolution obtained from absorption lineshapes. In particular, the variation in linewidths across a SECSY spectrum, which is a key component in elucidating motional dynamics, is clearly rendered in the pure absorption mode. A convenient method for introducing the necessary phase corrections for the slow-motional spectra is also provided.     

Soil moisture movement and groundwater recharge by tritium tracer tagging technique

The paper deals with the study of rate of soil moisture movement and recharge to groundwater system at Indian Agricultural Research Institute (IARI) farm for the years 1973, 1974 and 1975. The utility of artificially injected tritium, experimental techniques adopted and a quantitative determination of recharge and moisture movement rates are discussed. Corrections for upward movement of moisture after the end of monsoon have been used to calculate the average rates of water movement below the injection level and groundwater recharge. Average rates of soil moisture movement and recharge are 9.4 mm/d and 27.4% (193 mm) of monsoon precipitation for three years respectively. Under favourable conditions the diffusion coefficients for soil water system are calculated assuming Gaussian distribution of tritium concentrations in the soil profiles. The average value of diffusion coefficient is 2.5 × 10^?5 cm²/s for the sandy loam soils. The variation in recharge is mainly due to inherent variability in soil physical properties and vegetative cover. The technique is not found reliable for higher water table conditions on account of lateral flow.     

Environmentally benign synthesis of benzopyranopyrimidines

An ecologically benign method has been proposed for the synthesis of benzopyranopyrimidines by reaction of 4-hydroxycoumarins with aldehydes and urea or thiourea in the absence of a solvent under microwave irradiation. The proposed procedure improves the product yield and shortens the reaction time. Published in Russian in Zhurnal Organicheskoi Khimii, 2006, Vol. 42, No, 1. pp. 60-63. The text was submitted by the authors in English.     

Synthesis and characterization of polyamides and poly(amide-imide)s derived from 2,2-bis(4-aminophenoxy) benzonitrile

A series of polyamides and poly(amide-imide)s were prepared by the direct poly-condensation of 2,2-bis(4-aminophenoxy) benzonitrile [4-APBN] with aromatic dicarboxylic acids and bis(carboxyphthalimide)s in N-methyl-2-pyrrolidone [NMP] with triphenyl phosphite and pyridine as condensing agents. The synthesis of 4-APBN involves a nucleophilic displacement reaction in dipolar aprotic solvent with the alkali metal salt of p-aminophenol and an activated aromatic dichloro compound. Bis(carboxyphthalimide)s were prepared by condensation of 4,4^′-diaminodiphenylsulfone, 3,3^′-diaminodiphenylsulfone, 4,4^′-diaminodiphenylether, 4,4^′-diaminodiphenylmethane, 3,3^′-diaminobenzophenone, and trimellitic anhydride at a 1:2 molar ratio. The inherent viscosities of the resulting polymers were found to be in the range of 0.31-0.93 dl/g and glass transition temperatures between 235 and 298 °C. All polymers were soluble in aprotic polar solvents such as dimethylsulfoxide and NMP. The results of thermogravimetry revealed that all the polymers showed no significant weight loss before 400 °C. Wide-angle X-ray diffractograms revealed that all polymers were found to be amorphous except for the polyamide derived from isophthalic acid and polyamide-imides derived from diaminodiphenylether and diaminobenzophenone based bis(carboxyphthalimide)s.     

Zusammensetzung und Stabilität des Thallium(I)-Komplexes der β-Mercaptopropionsäure

Zusammenfassung Durch potentiometrische und konduktometrische Titrationen wird die genaue Zusammensetzung des Komplexes untersucht, der sich aus Thallium(I) und -Mercaptopropionsäure in wäßriger 0,1m-KNO₃-Lösung bildet. Es zeigt sich, daß Thallium nur einen einzigen Komplex bildet. Er ist farblos, hat die Molzusammensetzung 11 und liegt besonders im pH-Bereich 9,0–10,5 vor. Durch Anwendung der vonCalvin undMelchior erweiterten Meßmethode vonBjerrum wird für drei verschiedene Temperaturen der Wert der Komplexbildungskonstante bestimmt. Als Werte für logK ergaben sich bei 20° 2,775, bei 30° 2,850 und bei 40° 2,935. Die Werte der thermodynamischen Zustandsfunktionen berechnen sich für die Komplexbildung zu G=–3,95 kcal/Mol, H=–3,34 kcal/Mol und S=+2,01 cal/grad.

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The precise nature of the complex formation between Thallium(I) and -mercaptopropionic acid in aqueous 0.1M-KNO₃ has been investigated by potentiometric and conductometric titration techniques. It was found that Tl(I) forms only one, 11, colourless complex predominating at pH 9.0–10.5. The stability constant of the complex has been determined by applyingCalvin andMelchior's extention ofBjerrum's method at three different temperatures. The logK values were found to be 2.775, 2.850 and 2.935 at 20, 30 and 40° C respectively. The thermodynamic functions of complexation, G, H and S were also evaluated at 30° C and found to be –3.95 K-cal/mole, –3.34 K-cal/mole and +2.01 Cal/deg. respectively.

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Direct titrimetric microdetermination of tropeolin OO: I. Oxidation of tropeolin OO with ceric sulfate

Two quantitative methods for the determination of tropeoline OO in micro amounts are described. One of the methods is by direct titration with ceric sulfate resulting in the formation of a salt in the ratio of 1:2; in another method oxidation is effected at 51 equivalents. The reason for salt formation in the first method and the identification of formic acid is discussed. Maximum error for the first and second methods is 0.8 and 1.3%, respectively. The two methods are simple, accurate, and reproducible.     

Spin–other–orbit and spin–orbit interactions in ƒ2 and ƒ3 electron configurations

Expressions of the matrix elements of the spin–other–orbit and spin–orbit interactions for the various multiplets of all the states of ?²- and ?³-electron configurations are reported and used to evaluate the Hartree–Fock values of these interactions in the neutral atoms Ce(4?²), Pr(4?³), Ho(4?¹¹) and Er(4?¹²). The required values of the spin–spin parameters M, and the spin-orbit parameter ζ for these atoms were obtained using numerical Hartree–Fock wave functions.