Investigation of substituent effects on the 1H NMR spectra of chalcones

¹H NMR spectra of 26 substituted chalcones (3-aryl-1 phenyl-2-propene-1-ones and 1-aryl-3-phenyl-2-propene-1-ones) have been studied. The chemical shifts of the α and β protons to the carbonyl group were correlated with Hammett s? parameters. To gain information on the effect of the transmission of the resonance and inductive contributions of the substituents on the chemical shifts of H-α and H-β, two parameter correlations with ?? and ?? parameters were also perfomed. The chemical shifts of the aromatic protons of the para-disubstituted benzene ring correlated with the a_i substituent increments.     

Interactions in multicomponent systems containing surfactants. System silver iodide — methylene blue and sodium dodecyl sulphate

The precipitation and dissolution of AgI in the presence of methylene blue (MB · Cl) and sodium dodecyl sulphate (NaDS) was followed by X-ray diffraction analysis.At high MB · Cl concentration, the absence of AgI precipitates was observed, which is explained by considering the redox process MB⁺ + 2I^– MB^– + I₂. The decrease in I^– concentration causes dissolution or inhibition of growth of solid AgI which is significant at relatively high MB · Cl concentrations. The addition of NaDS causes the disappearance of these effects, which is explained by the incorporation of MB in NaDS micelles.These explanations are supported by the potentiometric measurements using Ag/Ag₂S and Pt electrodes.     

Xα SW study of bonding,photoelectron spectra and photoionization transition states of (cyclobutadiene)iron tricarbonyl

We report Xα SW MO calculations on (η²-C₄H₄)Fe(CO)₃ and its five transition states, formed by removing a half of an electron from each of the five uppermost filled MO_s. Eigenvalues in the transition states depend only slightly upon the MO from which the “high-ionization” occurs. The MOs are more polarized in the transition states than in the ground state. The C₄H₄-Fe bonding is highly covalent.     

NMR investigations on alanyl-[15% 13C, 95% 15N]-proline: 15N chemical shifts and 13C?15N coupling constants

The dipeptide alanylproline has been prepared with the proline residue both ¹³C (15%) and ¹⁵N (95%) enriched. ¹⁵N NMR spectra of alanylproline reveal signals for both possible conformations—cis and trans—of the dipeptide backbone in solution. Different pK values for both conformers are obtained from the pH dependence of the ¹⁵N chemical shifts using a least square programme based on the Henderson–Hasselbach equation. These different values are discussed in terms of interaction between the α-amino group and the carboxylate group and between the carboxylate oxygen and the carbonyl oxygen of the dipeptide via hydrogen bonding. Further evidence for these interactions is obtained from the pH dependence of the ratio of the ¹⁵N NMR signal intensities of the two conformers. One, two or three bonded ¹³C? ¹⁵N coupling constants measured in the ¹³C NMR high resolution spectra have different values in the cis and trans isomers of alanylproline and thus indicate different geometry in the pyrrolidine ring.     

Long-term interactions in clay/electrolyte systems

The influence of long-term interactions on sorption of cesium on montmorillonite has been examined. After initial fast sorption due to ion-exchange, the additional two-step sorption as a result of dissolution of main clay constituents, changes in solution chemistry and readsorption and/or precipitation of resultant species, were observed.     

NMR studies of metal-nonmetal transition in lithium-methylamine solutions

The Knight shift and the spin-lattice relaxation time of ⁷Li and ¹H have been measured in Li-methylamine solutions, in which a transition from the metallic to the nonmetallic states occurs.     

Self-Inquisitiveness: the Structure and Role of an Epistemic Virtue

The motivating virtue account claims that inquisitiveness or curiosity is the motivating epistemic virtue. In the case of self-knowledge, self-inquisitiveness, intrinsic and instrumental, is the motivating epistemic virtue that mobilizes other virtues, skills, and epistemic character virtues, needed to achieve such knowledge. Its proper object is substantial self-knowledge, knowledge of one’s dispositions and causal powers that has historically played a central role in philosophy, and is now, under various names, investigated by psychologists. It has been, until recently, comparatively neglected within analytical epistemology of self-knowledge. Self-inquisitiveness thus instantiates the general paradigm of curiosity-inquisitiveness that organizes and motivates other epistemic virtues (virtues-abilities and character virtues). And it is perhaps responsible for intrinsic value of self-knowledge.