Authors:M. Crespi, H. Zorel, C. Ribeiro, A. Costalonga, and C. Torres
5-Nitro-8-hydroxyquinoline (B) and 5,7-dinitro-8-hydroxyquinoline (C) were obtained from nitration of 8-hydroxyquinoline (A)
and purified in acetone medium and under heating in which the formation of (B) or (C) depends on the amount of HNO3 added. TG curves present mass loss in only one step before and after the melting point (Tm =76C (A) and 180C (B)) in different proportions as a function of the heating rate, characterising the sublimation and the
volatilisation processes, respectively. The thermal stability of the compounds follow the order: A (77C)<B (121C)<C (222C).
Kinetic parameters through TG curves, dynamic process, using heating rates of 1, 2.5, 5, 10 and 20C minȡ1 , enabled to obtain the following increasing order to the activation energy values of the compounds: 80.4 (A), 102.0 (B)
and 153.9 kJ mol−1 (C). Other kinetic parameters as pre-exponential and half-lifetime were also estimated.
A new chelating copolymer (HQDMA) has been synthesized through copolymerization of 8-hydroxyquinoline and dimethylolacetone
monomers in the presence of base as a catalyst. This newly developed copolymer ligand (H2L) has been used to prepare a series of five polymeric chelates (ML) by using Zn(II), Cu(II), Ni(II), Co(II) and Mn(II) metal
ions. Both the parent ligand and its metal chelates have been systemically investigated in detail to elucidate the chemical
structure and thermal behaviour by elemental analyses, spectral (IR and electronic) characterization, number-average molecular
determination and thermogravimetric analysis (TG). In addition to these, magnetic susceptibility measurements have also been
carried out for studying geometry and metal-ligand stoichiometry of polymeric chelates.
The chemical structure of polychelates on the basis of elemental and IR characterization suggests that the bidentate ligand
(H2L) coordinates to metal ions through oxygen atom of the phenolic hydroxyl group by replacing hydrogen atom and nitrogen of
the quinoline ring. The studies of magnetic moments and electronic spectra reveal that all polychelates with octahedral geometry
are paramagnetic in nature except that of Zn(II) chelate, which is diamagnetic. The thermogravimetric analysis of parent ligand
and its metal chelates have shown remarkable difference in mode of thermal decomposition and their thermal stabilities. The
kinetic parameter, energy of activation (Ea) of thermal decomposition has also been estimated by Broido method.
The substoichiometric separation of lanthanum was studied on the system EDTA —lanthanum—8-hydroxyquinoline. The optimum conditions
for the substoichiometric separation of lanthanum were calculated theoretically and these results were examined experimentally.
By using the two chelating agents, EDTA and 8-hydroxyquinoline, lanthanum could be separated substoichiometrically with good
accuracy and precision. This method was applied to the determination of lanthanum by activation analysis, and found to be
available for the determination of trace amount of lanthanum.
Authors:M. Rajasekaran, P. Anbusrinivasan, and S. Mojumdar
A novel nonlinear optical organic crystal 8-hydroxyquinoline has been grown by slow evaporation technique at room temperature
(RT) using chloroform as the solvent. The solubility of 8-hydroxyquinoline in chloroform has been determined at various temperatures.
The grown crystals were found to be transparent in the visible region. The grown crystals were characterized employing several
techniques such as UV, FT-IR, 1H NMR spectral analysis and TG–DTA studies. Preliminary measurements indicate that the second-harmonic generation efficiency
at a fundamental wavelength of 1064 nm is roughly 4.28 times that of KDP crystal.
Authors:I. Pastre, I. do Nascimento Oliveira, A. Moitinho, G. de Souza, E. Ionashiro, and F. Fertonani
The composite montmorillonite-8-hydroxyquinoline (Swy-1-8-HQ) was prepared by two different processes and studied by using
thermogravimetric analysis (TG/DTG and DSC), as well as helpful techniques as fluorescence in the UV-visible region and X-ray
diffraction. The composites developed fluorescent appearance, however with quantum poor efficiency and they exhibited distinct
TG and DSC thermal behavior. The fluorescence data of spectra associated to the TG/DT curves allowed to suggest that the 8-HQ
was present in the composites in two different circumstances: 1 - intercalated in the interlayer spaces (Swy-1-8-HQ2), rigidly
associated to the substrate feasible as a monolayer with the aromatic rings parallel to the silica layer; and/or, 2 - adsorbed
on the surface (Swy-1-8-HQ1), either as a bilayer formation or tilting of the molecules to the silicate layer sheet. All results
confirmed above are in agreement with X-ray diffraction patterns, once the interlayer space increases when 8-HQ is incorporated.
The experimental results confirm the formation of the composites in agreement with the method used in the preparation.
Authors:P. Ünak, T. Özkayalar, D. Özdemir, and F. Yurt
5-Chloro-7-amino-8-hydroxyquinoline which is a 8-hydroxyquinoline derivative was synthesized and its thorium(IV) and uranium(VI) complexes have been determined. 5-Chloro-7-nitro-8-hydroxyquinoline was prepared by nitration reaction of 5-chloro-8-hydroxyquinoline in aqueous solution of nitric acid. Then 5-chloro-7-amino-8-hydroxyquinoline was synthesized by reduction with sodium dithionite. Proton-ligand stability constants of 5-chloro-7-amino-8-hydroxyquinoline and stability constants of thorium(IV) and uranium(VI) complexes forming this ligand were determined by using the Irving-Rossotti method computing the Calvin-Bjerrum pH-titration data. As a result, thorium(IV) complexes were found more stable than uranium(VI) complexes.
The extraction of Co2+ from aqueous 0.1M acetate buffer by thenoyltrifluoroacetone (HTTA) and 8-hydroxyquinoline (HQ) and by a mixture of HTTA+phen and HQ+phen in benzene has been studied at various temperatures allowing for elucidation of the thermodynamics of extraction in the cases investigated.
The thermal behaviour of a series of oxovanadium(IV) complexes of halogenated derivatives of 8-hydroxyquinoline was investigated by means of TG and DTA measurements in oxygen atmosphere. V2O5 was the final pyrolysis residue in all cases.