Showing 3 results for Spectrophotometr
Roya Karamian,
Volume 15, Issue 2 (2-2015)
Abstract
Saponins are secondary metabolites that are found in many plants and some animals. These compounds are high molecular weight glycosides, consisting of a sugar moiety linked to a triterpene or steroid aglycone. Many saponins have detergency properties and give stable foam in water. The genus Silene L. with more than 700 species is one of the largest genera of the family Caryophyllaceae mainly distributed in north hemisphere. Saponins are one of important secondary metabolites in members of the genus. Quantitative and qualitative study of the saponins in the aerial parts and roots of three Silene species, namely S. ginodioca, S. spergulifolia and S. swertiifolia were carried out by spectrophotometry and TLC methods. In this study, 5 fractions were obtained from each plant part and in both parts of three species, fraction 1 contain the highest amounts of saponins. On the other hands, root extracts have a high amount of saponins. In addition, thin layer chromatography (TLC) of the extracts evaluated some saponins spots with different Rf.
Volume 18, Issue 49 (11-2006)
Abstract
The Complex formation reaction between iodine with tetrabutylammonium halides (TBAX) has been studied spectrophotometrically in chloroform solution at 25ºC. Various aspects of the spectra of iodine in the presence of various concentration of different tetrabutylammonium halides have been discussed in terms of electronic specifications of iodine and halides. In the case of tetrabutylammonium iodide and at high concentrations of iodine, both 1:1 (I3-) and 2:1 (I5-) complexes have been formed. Formation constants of charge transfer complexes were evaluated from the computer fitting of the absorbance-mole ratio data and found to vary in the order: TBAI>TBABr>TBACl>TBAF.
Volume 18, Issue 58 (8-2004)
Abstract
A spectrophotometric study concering the charge transfer interaction between 2,3-dichloro-5,6-dicyano-1,4-benzoquione (DDQ) and some benzophenoes has been carried out in chloroform at 25°C. Comparision of the spectra of the complexes of 1.2-dimethoxybenzene-DDQ and benzophenone-DDQ is indicative of two kinds of transitions: (i) n→π*, and (ii) π→π* respectively,). Formation constants of the resulting 1:1 molecular complexes were determined by using the Hildebrand method. The values of formation constants are in parallel with the charge density on the oxygen atoms of cabonyl groups. Also steric hindrance of substituents affects the stability of the resulting complexes. The shifts in stretching frequency of carbonyl groups of benzophenones, brought about upon complexation, further supports that donation takes place from oxygens of the carbonyl groups.
