Vibrational study of 8-quinolinol and 7-(4-ethyl-1-methyloctyl)-8-quinolinol (Kelex 100), two representative members of an important chelating agent family

Determination of Cadmium (II) in Aqueous Solutions by In Situ MID-FTIR-PLS Analysis Using a Polymer Inclusion Membrane-Based Sensor: First Considerations

Environmental monitoring is one of the most dynamically developing branches of chemical analysis. In this area, the use of multidimensional techniques and methods is encouraged to allow reliable determinations of metal ions with portable equipment for in-field applications. In this regard, this study presents, for the first time, the capabilities of a polymer inclusion membrane (PIM) sensor to perform cadmium (II) determination in aqueous solutions by in situ visible (VIS) and Mid- Fourier transform infrared spectroscopy (MID-FTIR) analyses of the polymeric films, using a partial least squares (PLS) chemometric approach. The influence of pH and metal content on cadmium (II) extraction, the characterization of its extraction in terms of the adsorption isotherm, enrichment factor and extraction equilibrium were studied. The PLS chemometric algorithm was applied to the spectral data to establish the relationship between cadmium (II) content in the membrane and the absorption spectra. Furthermore, the developed MID-FTIR method was validated through the determination of the figures of merit (accuracy, linearity, sensitivity, analytical sensitivity, minimum discernible concentration difference, mean selectivity, and limits of detection and quantitation). Results showed reliable calibration curves denoting systems' potentiality. Comparable results were obtained in the analysis of real samples (tap, bottle, and pier water) between the new MID-FTIR-PLS PIM based-sensor and F-AAS.

Final Report on the Safety Assessment of Oxyquinoline and Oxyquinoline Sulfate

Oxyquinoline is a heterocyclic phenol which is used as a fungicide and bactericide in cosmetic formulations at concentrations at, or less than 1.0%. Oxyquinoline is metabolized and excreted in the urine as glucuronides. The acute oral LD50 toxicity in rats was 1.2 g/kg. In subchronic studies, no deaths occurred in male and female rats at 5 doses up to 12,000 ppm or in male and female mice up to doses of 6000 ppm. Solid 100% Oxyquinoline was mildly irritating to rabbit skin and a 100 mg dose of Oxyquinoline was only slightly irritating to the eye. No sensitization test data were available for either of these cosmetic ingredients. Oxyquinoline and Oxyquinoline Sulfate were mutagenic when assayed using the Ames procedure with metabolic activation. Mutagenic activity was also demonstrated in the mouse lymphoma assay. Oxyquinoline was noncarcinogenic in several oral rodent feeding studies. The data from this negative oral carcinogenic assay were judged to be insufficient to evaluate the safety of use of Oxyquinoline and Oxyquinoline Sulfate when cosmetic products containing these ingredients are applied to the skin.

It is concluded that the available carcinogenicity and sensitization test data are insufficient to support a conclusion on the safety of Oxyquinoline and Oxyquinoline Sulfate as used in cosmetic products.

Synthesis, structure, and spectral and electrochemical properties of chromium(iii) tris-(8-hydroxyquinolinate)

Having the HOMO of chromium(iii) tris-(8-hydroxyquinolinate) mainly on metal 3d orbitals and the LUMO on the ligand leads to increased electrochemical stability.

Gelation-induced visible supramolecular chiral recognition by fluorescent metal complexes of quinolinol-glutamide

Three metal complexes consisting of Li(+), Zn(2+), and Al(3+) and quinolinol-functionalized L-glutamides (HQLG), (abbreviated as LiHQLG, Zn(HQLG)2, and Al(HQLG)3) were found to form fluorescent metallogels in several organic solvents. In solution, these chiral complexes showed neither any CD signal in the chromophore region nor chiral recognition of the chiral species. However, upon gel formation, the supramolecular chirality emerged because of the self-assembled nanostructures, which provided an opportunity for the chiral recognition of enantiomeric ligands. The metallogels showed different fluorescence changes when they met with enantiomeric (R,R)- or (S,S)-1,2-diaminocyclohexane. Among them, the Al(HQLG)3 metallogels did not show any change whereas the LiHQLG gels exhibited the same decrease in fluorescence. Interestingly, the Zn(HQLG)2 gels showed obviously different fluorescent color with respect to (R,R)- and (S,S)-1,2-diaminocyclohexane, thus providing visible chiral recognition via the naked eye. Such different recognition ability was discussed on the basis of the assembled chiral nanostructures and the primary molecular structures of the metal complexes. It was shown that both of them played important roles in chiral recognition.

Vibrational spectra of the Ga(III) complexes with oxine and clioquinol

The FTIR and FT-Raman spectra of the gallium(III) complexes of 8-hydroxyquinoline (oxine) and 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol), were recorded and briefly discussed by comparison with the spectra of the uncoordinated ligands and with some related species.

Final amended report on the safety assessment of oxyquinoline and oxyquinoline sulfate as used in cosmetics

Oxyquinoline is a heterocyclic phenol and Oxyquinoline Sulfate is its salt, both of which are described as cosmetic biocides for use in cosmetic formulations. In an earlier Cosmetic Ingredient Review (CIR) safety assessment, the available data were found insufficient to support safety. Currently, some uses are reported to the Food and Drug Administration (FDA) by industry, but industry reports to CIR indicate no use. In Europe, Oxyquinoline and Oxyquinoline Sulfate are accepted for use as stabilizers for hydrogen peroxide in rinse-off and leave-on hair care preparations, with concentration limitations. Oxyquinoline is metabolized and excreted in the urine as glucuronides. Oxyquinoline and Oxyquinoline Sulfate exhibit little acute or subchronic toxicity in animal studies. A 100-mg dose of Oxyquinoline was only slightly irritating to the eye. Oxyquinoline and Oxyquinoline Sulfate were genotoxic in certain Salmonella typhimirium strains with metabolic activation and in a mouse lymphoma assay. There was some evidence of increased chromosome aberrations in an in vitro study, and an increase in sister-chromatid exchanges (but not chromosome aberrations) in rats treated with Oxyquinoline, but no genotoxicity was found in a Drosophilia sex-linked recessive lethal test, mouse bone marrow micronucleus test, a rat bone marrow and hepatocyte micronucleus test, and unscheduled DNA synthesis in rat hepatocytes. Oxyquinoline did bind to DNA in the presence of liver enzymes. Although the International Agency for Research on Cancer concluded that the existing evidence is inadequate to determine carcinogenicity in animals, Oxyquinoline was noncarcinogenic in several rodent feeding studies, and newly available studies using genetically altered mice, in one case carrying the human c-Ha-ras gene, demonstrated that Oxyquinoline was not carcinogenic. In clinical tests, Oxyquinoline is neither an irritant nor a sensitizer when tested at 1% in petrolatum. The available data demonstrate that Oxyquinoline and Oxyquinoline Sulfate are safe as stabilizers for hydrogen peroxide in rinse-off hair care cosmetic products in the present practices of use. For leave-on cosmetic products, however, the absence of impurities and ultraviolet (UV) absorption data resulted in a finding that the available data are insufficient to support safety. The data needed in order to complete the safety assessment of Oxyquinoline and Oxyquinoline Sulfate in leave-on cosmetic products are (1) UV absorption data -- if significant absorption occurs, then photoirritation/photosensitization data will be needed; and (2) data on impurities.

Hydrogen bonding and dipolar interactions between quinolines and organic solvents. Nuclear magnetic resonance and ultraviolet-visible spectroscopic studies

Solvatochromic studies on quinoline (Q), 3-cyanoquinoline (CNQ), 3-bromoquinoline (BrQ) and 8-hydroxyquinoline (OHQ) in pure solvents and alcohol-cyclohexane mixtures have been performed. The results are compared with Proton Nuclear Magnetic Resonance, 1H NMR. studies and AMI calculations. Taft and Kamlet's solvatochromic comparison method was used to disclose solvent effects in pure solvents. These studies shows that the hydrogen bond acceptor ability of the Q ring is diminished and its polarity is increased by the presence of the cyano group in CNQ and the bromo group in BrQ. In OHQ, intramolecular hydrogen bonding has been observed. This interaction is weakened by the interaction with protic solvents. The studies in binary mixtures, alcohol-cyclohexane, show solute-solvent interactions, which compete with solvent self-association in the preferential solvation phenomena. Alcohols with strong ability to self-associate have less preference toward solvation of these compounds. The association constants for solute-ethanol systems were determined by 1H NMR. The results show that the solvent hydrogen bond donor ability is the main factor involved in the interaction with these solutes at the aza aromatic site.

Surface enhanced Raman scattering of 2,2' biquinoline adsorbed on colloidal silver particles

Surface enhanced Raman scattering (SERS) in silver sol and normal Raman spectra in the bulk and in solution of 2,2' biquinoline (BQ) molecule have been investigated. The observed Raman bands along with their corresponding FTIR bands have been assigned based on the established assignments of the vibrational bands of the parent napthalene and quinoline molecules. Existence of both the cis and trans form of the BQ molecule in solution and in the bulk are inferred from the normal Raman and FTIR spectra, whereas SERS study reveal that in the surface adsorbed state the molecule exists in the cis form. Definite evidence of the charge transfer interaction to the overall contribution in the SER enhancement have been reported. The excitation profile also supports the CT interaction. Estimated enhancement factor of the principal SERS bands indicate that the molecule is adsorbed on the silver surface through both the nitrogen atoms with the molecular plane almost perpendicular to the surface. This preferred orientation of the molecule is in conformity with its existence in the cis form in the surface adsorbed state.

pH-Dependent Surface-Enhanced Raman Scattering of 8-Hydroxy Quinoline Adsorbed on Silver Hydrosol

Surface-enhanced Raman scattering (SERS) of 8-hydroxy quinoline (HQ) adsorbed on silver hydrosols are compared with the FTIR and normal Raman spectrum in the bulk and in solution. Definite evidence of the charge transfer interaction to the overall contribution in the SER enhancement has been reported. The excitation profile study also supports the evidence of a charge transfer interaction. The effect of pH variation on the SER band intensity is explained in terms of chemisorption of the molecule on bare and chlorinated silver surfaces. The apparent enhancement factor calculations of the principal Raman bands indicate that in the surface-adsorbed state, an HQ molecule is oriented neither flat nor vertical to the silver surface but is tilted. Copyright 2000 Academic Press.