Search

New solid compounds of Tb(III), Ho(III), Er(III) and Yb(III) with chrysin were synthesized and characterized by elementary analysis, thermogravimetric studies and magnetic measurements. The molecular formula of the complexes is Ln(C15H9O4)3 · 4H2O where Ln is the cation of lanthanides. The oxidation state of metal ion in the complexes does not change and equals +3. The thermogravimetric analysis shows that two water molecules are present in the inner coordination sphere of the complex and the two molecules are in the outer sphere. The structure of the complexes was determined on the basis of UV–visible, IR and 1H NMR spectroscopies. It was found that chelation of the metal ion occurs at the 5-hydroxy-4-keto site. [ABSTRACT FROM AUTHOR]

The melting temperature of nine piperidinoethyl esters of alkoxyphenylcarbamic acid (hexaoxy-octyloxy) including all site isomers was investigated. The analyses were performed using DSC apparatus, sample mass ranged from 0.2 to 2.5 mg, heating rate was 5 K min-1 and in static air atmosphere. On the basis of melting peak, thermodynamic figures like: enthalpy, entropy, height and area of the peak and temperature of the partial peak were fixed. For evaluation of the results Principal Component Analysis was applied. Thanks to this method the influence of length (mass) and position of alkoxy substituents on the thermodynamic parameters of melting of compounds under investigation were determined. [ABSTRACT FROM AUTHOR]