Bioinspired nanoarchitectonics at the air-water interface to understand the interaction of lipids with a Europium-coordinated quinoline derivative.

5SO3H-8-hydroxyquinoline coordinated to Europium (Eu-5SO3-HQ) was incorporated in biomembrane models using Langmuir monolayers. Dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylserine (DPPS) were employed, representing mammalian cells and dioctadecyldimethylammonium bromide (DODAB) as a positively charged lipid to study the contrast with negatively charged lipids. Tensiometric, rheological and spectroscopic techniques were employed to characterize Eu-5SO3-HQ- lipid monolayer interactions. The complex condenses all the monolayer indicating interactions with the lipids' polar heads, but with distinctive effects on the mechanical and rheological properties. While the complex decreases the compression and elastic moduli of DPPC and DPPS monolayers, it increases for DODAB, also decreasing its lateral viscosity. Infrared spectroscopy shows that the interaction of Eu-5-SO3-HQ alters the ordering of the lipids' alkyl chains, impacting the monolayer's molecular packing. These results show that the interaction of Eu-5SO3-HQ with lipid monolayers at the air-water is modulated by the composition of the polar head, which can be supportive in the preparation of nanodevices for molecular probing.

Quinoline-derivative coordination compounds as potential applications to antibacterial and antineoplasic drugs.

Quinoline-derivative coordination compounds were synthesized with Zn(II), Al(III), Cu(II), Ru(II) producing 1-4 compounds using 5-nitro-8-hydroxyquinoline and 5-8 compounds using 5-chloro-8-hydroxyquinoline. These coordination compounds were characterized by elemental analysis and 1H NMR, IR, UV-Vis and fluorescence spectroscopies, representing the coherent data matched all compounds. Myelotoxicity data, as well as the biochemical data, depicted the compounds have low cytotoxicity towards the blood cells. All coordination compounds displayed slight antimicrobial activity against E. coli, S. aureus, P. aeruginosa and E. faecalis; [RuCl(NO)(5-chloro-8-oxyquinoline)2] compound (8) represent the best result to inhibitions of Gram-positive and Gram-negative bacteria. Antineoplasic action depicted the [Ru(NO)(5-nitro-8-oxyquinoline)2Cl] compound (4) as a potential chemotherapeutic agent against MCF-7 (a breast cancer cell line), compared to cisplatin (Platistine® CS) and cyclophosphamide (Genuxal®) drugs.

Selective azo dye-based colorimetric chemosensor for F-, CH3COO- and PO43.

Developing anionic receptors is a huge challenge, especially those using hydrogen bonds to interact with the analytes. Azobenzene-derivative selective chemosensor has been evaluated for anion recognition properties. 2­(4­Hydroxiazobenzene)benzoic acid (HABA) has two hydrogens groups available for interaction; one is the phenol group and the other is the carboxylic acid group, enabling interaction with cations and anions. Subsequently titrations of chromophore 2­(4­hydroxiazobenzene) benzoic acid were performed with cations and anions; however, only the interactions with fluoride, acetate, and phosphate were significant. These data demonstrated the sensitivity of the ligand HABA by these anions, characterized by the displacement of the absorbance bands at 372nm to 491nm in acetonitrile. The association constants found to fluoride, acetate, and phosphate were 1.56×104±0.28, 1.25×104±0.60, and 1.90×104±0.67mol-1dm3 respectively. 1H NMR titrations data confirmed association constants values in agreement with those of UV-Vis, besides showing evidence of the analyte interaction by the hydrogen-bonding of the carboxylic acid group. Overall, UV-Vis limit of detection data for fluoride (1.05×10-7moldm-3), acetate (3.77×10-8moldm-3) and phosphate (3.00×10-8moldm-3), support that HABA can detect low concentration of these anions.

A Cr(VI) selective probe based on a quinoline-amide calix[4]arene.

A new quinoline-amide calix[4]arene 3-receptor for detection of hazardous anions and cations have been synthesized. The 3-receptor was examined for its sensing properties towards several different anions (Cr2O72-, SCN-, F-, Cl-, NO3-) and metal ions (Hg2+, Cd2+, Ag+) by UV-vis and fluorescence spectroscopies. It was detected that the 3-receptor has only sensing ability for Cr2O72- and Hg2+ ions, resulting in the association constants higher for Cr2O72- than to the Hg2+ ions. High selectivity towards Cr2O72- were also observed by fluorescence measurement among other ions (F-, Cl-, SCN-, Hg2+, Cd2+, Ag+) with a low limit of detection (7.36×10-6moldm-3). Proton NMR anion-binding investigations revealed a strong interaction of Cr2O72- anion with NH and CH groups of the receptor, showing that the combination with hydrogen-bonds donor groups strengthened the anion receptor association. Furthermore, remarkable association constants for dichromate anion obtained by all techniques strongly suggest the 3-receptor as a selective Cr(VI) sensor.

Fluorescence in complexes based on quinolines-derivatives: a search for better fluorescent probes.

Quinoline-derived fluorescent complexes were designed; synthesized by the reaction of 5-nitro-8-hydroxyquinoline and 5-chloro-8-hydroxyquinoline with Al(3+), Mg(2+), Zn(2+), and Cd(2+) salts (1-8); and characterized. The (1)H NMR spectra of complexes 1 and 5, containing Al(3+), were consistent with an octahedral structure having approximate D3 symmetry, and the results supported the favored facial isomer (fac). Data for complexes 2-4 and 6-8 supported the formation of tetrahedral structures. Intense luminescence was detected for complexes 5-8, even with the naked eye, as indicated by quantum yield values of 0.087, 0.094, 0.051, and 0.021, respectively. Furthermore, in contrast to 5-nitro-8-hydroxyquinoline, the 5-chloro-8-hydroxyquinoline ligand exhibited bands at different energies depending on the coordinated metal, which supported its potential application in ionic and biological probes, as well as in cell imaging.

Evaluation of the biological effects of 5-Cl-8-oxyquinolinepropoxycalix[4]arene and 8-oxyquinolinepropoxycalix[4]arene in vitro and in vivo.

The development of antibacterial and antifungal drugs has been the target of several pharmaceutical and chemical industries mainly due to the lack of effective drugs with low or no side effect. In this work, studies were conducted both in vitro and in vivo with 8-oxyquinolinepropoxycalix[4]arene (A) and 5-Cl-8-oxyquinolinepropoxycalix[4]arene (B) ligands, showing fairly good results. Cytotoxicity and fungicidal actions of compounds A and B were determined in Wistar male rats and peritoneal macrophages of mice. A slight change in the total of leukocytes and erythrocytes was observed on the hematologic assays, showing almost no inflammation after using both compounds in Wistar male rats. We have also noted some, but not significant, alteration in liver enzymes representing modest hepatotoxicity. Cytotoxicity of peritoneal macrophages, in the presence of compound A or B, showed 50% of survival of macrophages. On the other hand, macrophages previously infected with Candida albicans and treated with substance A or B exhibited an increased cytokine IL-10 at 24h incubation. By checking the effect of substance A or B on growing C. albicans, the results pointed that these substances revealed antifungal activity against C. albicans, in 24h culture with a reduction of yeast cells.

Photoluminescence and thermoanalytical studies of complexes based on 5-Cl-8-hydroxyquinoline and calix[4]arene ligands.

A innovative 5-Cl-8-oxyquinolinepropoxycalix[4]arene ligand (2) have been prepared, exhibiting, at room temperature, blue fluorescent light emission and resulting in shift band to green fluorescent light (fluorescence mode) in the presence of coordinated Eu(III) and Tb(III) ions. Terbium complex presented phosphorescence emission as noted by typical bands at 490 nm, 545 nm and 585 nm. TG/DTG data exhibited typical thermal behavior for these compounds, however DSC curves showed the melting temperature near 300 °C for the samples, demonstrating an unusual thermal stability when quinoline derivatives are attached to calix[4]arene matrix. This fact strongly suggests an effective approach to preparing the photoluminescent compound associating high chemical and thermal stability.