Authors:P. Lopez-de-Alba, B. Urbina, J. Alvarado, G. Andreu, and J. Lopez
Collection of uranium by salicyliden and glutariliden chitosans /Schiff's Bases/ was investigated to obtain information on uranium recovery from ores, especially carnotites. The collection of uranium by salicyliden /SDQ/ and glutariliden /GDQ/ chitosans was very rapid during the first 20 min and was affected by the pH of the solution, contact time and temperature. Uranium collected on SDQ and GDQ was easily eluted with diluted sodium bicarbonate solution. Also uranyl and vanadyl ions were separated from each other by using these biopolymers.
Solid complexes of two derivatives of Schiff bases SAT and SAZ with Pr(III), Nd(III), Gd(III), Dy(III), Ho(III), Er(III) and
Yb(III) were prepared and characterized by elemental analysis , IR spectra and TG. The suggested formula of the obtained solid
complexes is [MLCl2(H2O)n] for sat and [MLCl (H2O)n] for SAZ where M=trivalent lanthanide ion, L=deprotonated ligand and n=2-3. The TG gives information about the coordinated water molecules, thermal stability and the coordination number of M which was found to be 6–8. A scheme of thermal decomposition of the complexes is also proposed. Comparison of the IR spectra
of the ligands with those of their complexes indicate the center of chelation in SAT and SAZ which act as tridentate ligands.
Solid complexes of five derivatives of thio-Schiff bases with La(III) and Ce(III) ions were prepared and characterized by
elemental and thermogravimetric analyses. The suggested general formula of the solid complexes is [ML2(H2O)X]·2H2O, whereM=trivalent lanthanide ion,L=Schiff base andX=Cl− or ClO
. Information about the water of hydration, the coordinated water molecules, the coordination chemistry and the thermal stability
of these complexes was obtained and is discussed. Additionally, a general scheme of thermal decomposition of the lanthanide-Schiff
base complexes is proposed.
Authors:Yanxia Geng, Zhan Li, Duoqiang Pan, and Wangsuo Wu
For the selective extraction of Am(III) and Eu(III), quadridentate divalent phenolic Schiff bases-bis-salicylaldehyde ethylenediamine
(H2salen) was investigated as a kind of extractant. The influences of alkaline cation, inorganic anion, ionic strength, pH and
the concentration of H2salen on the distribution ratio of Am(III) and Eu(III) were investigated in detail. As a result, Am(III) and Eu(III) made
anionic 1:1 complexes with the ligand (H2salen) and could be extracted into nitrobenzene as ion-pairs with a suitable monovalent counter anion in the aqueous solution,
the extracted species were possibly of the type Am(H2salen) Eu(salen)Cl and Eu(H2salen)Cl3, respectively. The extractability of Eu(III) was significantly stronger than that of Am(III) and the maximum separation factor,
SF(Am/Eu), was 96 at pH 4.0. The results indicated that H2salen had good selectivity for Am(III) and Eu(III).
Four new complexes of UO2(II) and Th(IV) with bis-Schiff bases, derived from N,N'-bis[(l-phenyl-3-methyl-5-oxo-4-pyrazolinyl)-a-furylmethylidyne]-1,2-propylenediimine [1,2-BPMOPFP-H2] and N,N'- bis[(l-phenyl-3-methyl-5-oxo-4-pyrazolinyl)-a-furylmethylidyne]-1,3-propylenediimine [1,3-BPMOPFP-H2], were synthesized and characterized by elemental analysis, IR, UV, 1HNMR spectroscopy, and molar conductivity. The general formula of the complexes was confirmed to be [UO2(BPMOPFP)], [Th(BPMOPFP)(NO3)]NO3. A possible structure for the complexes have been proposed.
Authors:Rodica Olar, Mihaela Badea, Dana Marinescu, Veronica Lazar, and Carmen Chifiriuc
Schiff bases obtained by the condensation of 2-amino-5-mercapto-1,3,4-thiadiazole with 2,4-pentandione or 1-phenyl-1,3-butandione
were synthesized and characterized in order to obtain polydentate ligands HL1 and HL2, respectively. The complexes with these ligands of the type M(L)Cl·nH2O [(1) M:Ni, L:L1, n = 0.5; (3) M:Ni, L:L2, n = 0.5]; [(2) M:Cu, L:L1, n = 1; (4) M:Cu, L:L2, n = 0] were also synthesized and characterized. The modifications evidenced in IR spectra of complexes were correlated with
the presence of monodeprotonate Schiff bases. The electronic spectra display the characteristic pattern of square-planar stereochemistry.
The in vitro qualitative and quantitative antimicrobial activity assays showed that the new complexes exhibited variable antimicrobial
activity. The thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany
them. Schiff bases and complexes have a similar thermal behaviour. Processes as water elimination, melting, chloride anion
removal as well as oxidative degradation of the organic ligands were observed.
Authors:Rodica Olar, Mihaela Badea, Dana Marinescu, and Ramona Mardale
ability to perform the DNA cleavage [ 21 ]. Also, complexes with Schiffbases derived from 1,2,4-triazine display antibacterial activities against both Gram-negative and Gram-positive strains [ 22 ].
Thermal stability of some complexes with
Authors:F. Lemos, M. Muraro, J. Zukerman-Schpector, É. Cavalheiro, and E. Dockal
The iron(II) complex of the Schiff bases trans-N,N'-bis(salicylidene)-1,2-cyclohexanediamine (Salcn), manganese(II) and vanadyl complexes of the Schiff bases cis- andtrans-N,N'-bis(salicylidene)-1,2-cyclohexanediamine (Salcn) were prepared and characterized by IR spectroscopy, and elemental analysis.
These new complexes were submitted to thermal analysis (TG and DSC) under dynamic air atmosphere. The differences in the decomposition
profiles were related to the structure of isomers and decomposition intermediates were characterized according to their X-ray
diffraction pattern and by their infrared spectrum.