Sm(â ¢), Gd(â ¢), and Eu(â ¢) complexes with 8-hydroxyquinoline derivatives as potential anticancer agents via inhibiting cell proliferation, blocking cell cycle, and inducing apoptosis in NCI-H460 cells.

Four lanthanide complexes with 8-hydroxyquinoline-2-aldehyde-2-hydrazinopyridine (H-L1), 8-hydroxyquinoline-2-aldehyde-2-hydrazimidazole (H-L2): [Sm(L1)2][Sm(L1)(NO3)3]·CHCl3·2CH3OH (1), [Gd(L1)2][Gd(L1)(NO3)3]·CHCl3·2CH3OH (2), [Sm(L2)(NO3)2]2·CH3OH (3), and [Eu(L2)(NO3)2]2·CH3OH (4) were synthesized and characterized. In vitro cytotoxicity evaluation showed that the ligands and four lanthanide complexes exhibited cytotoxicity to the five tested tumor cell lines. Among them, complex 1 showed the best antiproliferative activity against NCI-H460 tumor cells. Mechanistic studies demonstrated that complex 1 arrested the cell cycle of NCI-H460 cells in G1 phase and induced mitochondria-mediated apoptosis, which resulted in the loss of mitochondrial membrane potential, enhanced intracellular Ca2+ levels and reactive oxygen species generation. In addition, complex 1 affected the expression levels of intracellular apoptosis-related proteins and activated the caspase-3/9 in NCI-H460 cells. Therefore, complex 1 is a potential anticancer agent.

8-Hy-droxy-quinolinium tri-chlorido-(pyridine-2,6-di-carb-oxy-lic acid-κ3 O,N,O')copper(II) dihydrate.

The title compound, (C9H8NO)[CuCl3(C7H5NO4)]·2H2O, was prepared by reacting CuII acetate dihydrate, solid 8-hy-droxy-quinoline (8-HQ), and solid pyridine-2,6-di-carb-oxy-lic acid (H2pydc), in a 1:1:1 molar ratio, in an aqueous solution of dilute hydro-chloric acid. The CuII atom exhibits a distorted CuO2NCl3 octa-hedral geometry, coordinating two oxygen atoms and one nitro-gen atom from the tridentate H2pydc ligand and three chloride atoms; the nitro-gen atom and one chloride atom occupy the axial positions with Cu-N and Cu-Cl bond lengths of 2.011 (2) Šand 2.2067 (9) Å, respectively. In the equatorial plane, the oxygen and chloride atoms are arranged in a cis configuration, with Cu-O bond lengths of 2.366 (2) and 2.424 (2) Å, and Cu-Cl bond lengths of 2.4190 (10) and 2.3688 (11) Å. The asymmetric unit contains 8-HQ+ as a counter-ion and two uncoordinated water mol-ecules. The crystal structure features strong O-H⋯O and O-H⋯Cl hydrogen bonds as well as weak inter-actions including C-H⋯O, C-H⋯Cl, Cu-Cl⋯π, and π-π, which result in a three-dimensional network. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing involving the main residues are from H⋯Cl/Cl⋯H inter-actions, contributing 40.3% for the anion. Weak H⋯H contacts contribute 13.2% for the cation and 28.6% for the anion.

Crystal structure of bis-(µ2-5-nona-noylquinolin-8-olato)bis-[aqua-dichlorido-indium(III)].

Crystallization of 5-nona-noyl-8-hy-droxy-quinoline in the presence of InCl3 in aceto-nitrile yields a dinuclear InIII complex crystallizing in the space group P. In this complex, [In2(C18H22NO2)2Cl4(H2O)2], each indium ion is sixfold coordinated by two chloride ions, one water mol-ecule and two 8-quinolino-late ions. The crystal of the title complex is composed of two-dimensional supra-molecular aggregates, resulting from the linkage of the Owater-H⋯O=C and Owater-H⋯Cl hydrogen bonds as well as bifurcated Carene-H⋯Cl contacts.

Nitroxoline: treatment and prevention of urinary tract infections from the urologist's perspective.

Introduction: Nitroxoline is an old antimicrobial agent with a broad spectrum of pharmacological applications and a unique mechanism of action. However, its use in the treatment and prevention of urinary tract infections (UTIs) has not been popular in the recent past. Recently, nitroxoline is gaining interest, due to frequent drug-resistance in uropathogens. Unfortunately, there are few modern clinical trials assessing this antibiotic. Also, older researchers often do not meet current scientific standards. This review seeks to provide a comprehensive overview of nitroxoline as a viable option in treating uncomplicated lower UTIs. Material and methods: A comprehensive literature search regarding the use of nitroxoline in UTIs was conducted using Pubmed, Cochrane Library and Embase databases. A cross-reference search was also performed. Case reports, editorials and non-peer-reviewed literature were excluded from further analysis. As a result, 21 publications were included in this review. Results: The available literature on nitroxoline's mechanism of action, pharmacokinetics, minimum inhibitory concentrations, in vitro activity and resistance rates strongly suggests that nitroxoline is a potent broad-spectrum antimicrobial agent. Moreover, clinical efficacy of the drug was analyzed - 2 articles proved high eradication rates in women with uncomplicated lower UTIs and 1 reported unsuccessful treatment in geriatric patients with lower complicated and uncomplicated UTIs. Finally, the present data on adverse effects indicate that nitroxoline is well-tolerated. Conclusions: Nitroxoline is an obscure, yet potentially effective and safe antimicrobial agent in uncomplicated lower UTIs. Unfortunately, it is available only in a few countries. Nonetheless, nitroxoline can be useful in urological practice.

Synthesis, spectroscopic characterization, DFT calculations, in silico-ADMET and molecular docking analysis of novel quinoline-substituted 5H-chromeno [2,3-b] pyridine derivatives as antibacterial agents.

A convenient, straightforward, and effective one-step reaction for the synthesis of a three-component compound of biologically relevant novel 2,4-diamino-5-(8-hydroxyquinolin-7-yl)-5H-chromeno[2,3-b] pyridine-3-carbonitrile derivatives was designed and synthesized. The synthesis was developed by the reaction between salicylaldehyde 1, 8-hydroxyquinoline 2, 2-aminopropene-1,1,3-tricarbonitrile 3, and the catalytic amount of triethylamine in ethanol at 78 °C. This methodology has many beneficial features, including the use of inexpensive and non-hazardous starting materials, single-flask reactions, optimized reaction conditions, the termination of intermediate isolation, easy workup, reducing organic waste products, being chromatography-free, and decreasing the reaction time along with quantitative yields with high functional group tolerance. A proposed mechanism with supporting experimental data is presented, including 1H NMR, 13C NMR, 2D NMR (HMBC, COSY, HSQC), mass, and IR spectroscopy, which are used to characterize the complete derivatives. All synthesized compounds were evaluated in vitro for their antibacterial activities against Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa bacterial strains via the agar-well diffusion method compared with the reference drug gentamicin. The data indicated that compounds 4A, 4F, 4G, 4 J, and 4K consistently demonstrated strong antimicrobial activity against Gram-positive and Gram-negative bacteria. Furthermore, a molecular docking investigation was carried out to gain insight into the binding mode of the most promising compounds via the crystal structure of the S. aureus DNA gyrase complex with ciprofloxacin (PDB ID: 2XCT). Density functional theory (DFT) calculations were performed to determine the various molecular properties of the synthesized novel 2,4-diamino-5-(8-hydroxyquinolin-7-yl)-5H-chromeno [2,3-b] pyridine-3-carbonitrile derivatives (4A-4 M). On the basis of the reactive sites explored by the molecular electrostatic potential maps, the antibacterial activities of the compounds were screened.

Design, Synthesis, and Anticancer and Antibacterial Activities of Quinoline-5-Sulfonamides.

A series of new unique acetylene derivatives of 8-hydroxy- and 8-methoxyquinoline- 5-sulfonamide 3a-f and 6a-f were prepared by reactions of 8-hydroxy- and 8-methoxyquinoline- 5-sulfonyl chlorides with acetylene derivatives of amine. A series of new hybrid systems containing quinoline and 1,2,3-triazole systems 7a-h were obtained by reactions of acetylene derivatives of quinoline-5-sulfonamide 6a-d with organic azides. The structures of the obtained compounds were confirmed by 1H and 13C NMR spectroscopy and HR-MS spectrometry. The obtained quinoline derivatives 3a-f and 6a-f and 1,2,3-triazole derivatives 7a-h were tested for their anticancer and antimicrobial activity. Human amelanotic melanoma cells (C-32), human breast adenocarcinoma cells (MDA-MB-231), and human lung adenocarcinoma cells (A549) were selected as tested cancer lines, while cytotoxicity was investigated on normal human dermal fibroblasts (HFF-1). All the compounds were also tested against reference strains Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 and representatives of multidrug-resistant clinical isolates of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant E. faecalis. Only the acetylene derivatives of 8-hydroxyquinoline-5-sulfonamide 3a-f were shown to be biologically active, and 8-hydroxy-N-methyl-N-(prop-2-yn-1-yl)quinoline-5-sulfonamide (3c) showed the highest activity against all three cancer lines and MRSA isolates. Its efficacies were comparable to those of cisplatin/doxorubicin and oxacillin/ciprofloxacin. In the non-cancer HFF-1 line, the compound showed no toxicity up to an IC50 of 100 µM. In additional tests, compound 3c decreased the expression of H3, increased the transcriptional activity of cell cycle regulators (P53 and P21 proteins), and altered the expression of BCL-2 and BAX genes in all cancer lines. The unsubstituted phenolic group at position 8 of the quinoline is the key structural fragment necessary for biological activity.

Synthesis of Tumor Selective Indole and 8-Hydroxyquinoline Skeleton Containing Di-, or Triarylmethanes with Improved Cytotoxic Activity.

The reaction between glycine-type aminonaphthol derivatives substituted with 2- or 1-naphthol and indole or 7-azaindole has been tested. Starting from 2-naphthol as a precursor, the reaction led to the formation of ring-closed products, while in the case of a 1-naphthol-type precursor, the desired biaryl ester was isolated. The synthesis of a bifunctional precursor starting from 5-chloro-8-hydroxyquinoline, morpholine, and ethyl glyoxylate via modified Mannich reaction is reported. The formed Mannich base 10 was subjected to give bioconjugates with indole and 7-azaindole. The effect of the aldehyde component and the amine part of the Mannich base on the synthetic pathway was also investigated. In favor of having a preliminary overview of the structure-activity relationships, the derivatives have been tested on cancer and normal cell lines. In the case of bioconjugate 16, as the most powerful scaffold in the series bearing indole and a 5-chloro-8-hydroxyquinoline skeleton, a potent toxic activity against the resistant Colo320 colon adenocarcinoma cell line was observed. Furthermore, this derivative was selective towards cancer cell lines showing no toxicity on non-tumor fibroblast cells.

Identification of antimycobacterial 8-hydroxyquinoline derivatives as in vitro enzymatic inhibitors of Mycobacterium tuberculosis enoyl-acyl carrier protein reductase.

The increasing prevalence of drug-resistant Mycobacterium tuberculosis strains stimulates the discovery of new drug candidates. Among them are 8-hydroxyquinoline (8HQ) derivatives that exhibited antimicrobial properties. Unfortunately, there is a lack of data assessing possible targets for this class mainly against Mycobacterium tuberculosis enoyl-acyl carrier protein reductase (MtInhA), a validated target in this field. Thus, the main purpose of this study was to identify 8HQ derivatives that are active against M. tuberculosis and MtInhA. Initially, the screening against the microorganism of a small antimicrobial library and its new derivatives that possess some structural similarity with MtInhA inhibitors identified four 7-substituted-8HQ (series 5 - 5a, 5c, 5d and 5i) and four 5-substituted-8HQ active derivatives (series 7 - 7a, 7c, 7d and 7j). In general, the 7-substituted 8-HQs were more potent and, in the enzymatic assay, were able to inhibit MtInhA at low micromolar range. However, the 5-substituted-8-HQs that presented antimycobacterial activity were not able to inhibit MtInhA. These findings indicate the non-promiscuous nature of 8-HQ derivatives and emphasize the significance of selecting appropriate substituents to achieve in vitro enzyme inhibition. Finally, 7-substituted-8HQ series are promising new derivatives for structure-based drug design and further development.

Zn(II) enhances the antimicrobial effect of chloroxine and structural analogues against drug-resistant ESKAPE pathogens in vitro.

The emerging antibiotic-resistant bacteria, especially the "ESKAPE" pathogens, pose a continuous threat to global health. In this study, we explored metalloantibiotics as promising therapeutics and innovative antimicrobial agents. The role of metal in the antimicrobial activity of chloroxine (5,7-dichloro-8-hydroxyquinoline), as a metalloantibiotic, was investigated by minimal inhibit concentration (MIC) assay and a series of assays, including growth curve, time-killing, and UV-visible spectroscopy and PAR (4-(2-pyridylazo)-resorcinol) competition assays. Both chloroxine and its structural analogues exhibited increased antibacterial potency against Gram-positive bacteria compared to Gram-negative bacteria. The introduction of exogenous manganese or zinc ions significantly boosted chloroxine's antibacterial efficacy against Gram-negative bacteria, including the notorious ESKAPE pathogens. However, the enhanced antibacterial activity induced by zinc ions could be negated in the presence of copper or ferrous iron ions, as well as changes in oxygen availability, highlighting the involvement of proton motive force, oxidative and antioxidative systems. Notably, chloroxine effectively inhibited the enzymatic activity of superoxide dismutase (SOD). In addition, chloroxine could reverse polymyxin and carbapenem resistance in E. coli in vitro. Therefore, these results suggested that chloroxine with zinc ions are promising therapeutics and antibiotics potentiator to combat multidrug-resistant ESKAPE pathogens.

Mitochondrial-targeted cyclometalated Ir(III)-5,7-dibromo/dichloro-2-methyl-8-hydroxyquinoline complexes and their anticancer efficacy evaluation in Hep-G2 cells.

Both 8-hydroxyquinoline compounds and iridium (Ir) complexes have emerged as potential novel agents for tumor therapy. In this study, we synthesized and characterized two new Ir(III) complexes, [Ir(L1)(bppy)2] (Br-Ir) and [Ir(L2)(bppy)2] (Cl-Ir), with 5,7-dibromo-2-methyl-8-hydroxyquinoline (HL-1) or 5,7-dichloro-2-methyl-8-hydroxyquinoline as the primary ligand. Complexes Br-Ir and Cl-Ir successfully inhibited antitumor activity in Hep-G2 cells. In addition, complexes Br-Ir and Cl-Ir were localized in the mitochondrial membrane and caused mitochondrial damage, autophagy, and cellular immunity in Hep-G2 cells. We tested the proteins related to mitochondrial and mitophagy by western blot analysis, which showed that they triggered mitophagy-mediated apoptotic cell death. Remarkably, complex Br-Ir showed high in vivo antitumor activity, and the tumor growth inhibition rate was 63.0% (P < 0.05). In summary, our study on complex Br-Ir revealed promising results in in vitro and in vivo antitumor activity assays.

Insights into the antineoplastic activity and mechanisms of action of coumarin-coordinated 8-hydroxyquinoline ruthenium(II/III) compounds.

Ruthenium(II/III) coordination compounds have gained widespread attention as chemotherapy drugs, photosensitizers, and photodynamic therapy reagents. Herein, a family of 11 novel coumarin-coordinated 8-hydroxyquinoline ruthenium(II/III) compounds, i.e., [RuII2(µ2-Cl)2(QL1a)2(DMSO)4] (YNU-4a = Yulin Normal University-4a), [RuII2(µ2-Cl)2(QL1b)2(DMSO)4] (YNU-4b), [RuII2(µ2-Cl)2(QL1c)2(DMSO)4] (YNU-4c), [RuII2(µ2-Cl)2(QL1d)2(DMSO)4]⋅2CH3OH (YNU-4d), [RuII(QL1e)2(DMSO)2] (YNU-4e), [RuIII(QL1e)2(QL3a)] (YNU-4f), [RuIII(QL1e)2(QL3b)] (YNU-4g), [RuIII(QL1e)2(QL3c)] (YNU-4h), [RuIICl2(H-QL3a)2(DMSO)2] (YNU-4i), [RuIICl2(H-QL3b)2(DMSO)2] (YNU-4j), and [RuIICl2(H-QL3c)2(DMSO)2] (YNU-4k), featuring the coligands 5,7-diiodo-8-hydroxyquinoline (H-QL1a), 5,7-dichloro-8-quinolinol (H-QL1b), 5-chloro-7-iodo-8-hydroxyquinolin (H-QL1c), 5,7-dibromo-8-hydroxyquinoline (H-QL1d), and 5,7-dichloro-8-hydroxy-2-methylquinoline (H-QL1e) and the main ligands 6,7-dichloro-3-pyridin-2-yl-chromen-2-one (H-QL3a), 6-bromo-3-pyridin-2-yl-chromen-2-one (H-QL3b), and 6-chloro-3-pyridin-2-yl-chromen-2-one (H-QL3c), respectively. The structure of compounds YNU-4a-YNU-4k was fully confirmed by conducting various spectroscopic analyses. The anticancer activity of YNU-4a-YNU-4k was evaluated in cisplatin-resistant A549/DDP lung cancer cells (LC549) versus normal embryonic kidney (HEK293) cells. Notably, compound YNU-4f bearing QL1e and QL3a ligands showed a more pronounced antiproliferative effect against LC549 cells (IC50 = 1.75 ± 0.09 µM) with high intrinsic selectivity toward LC549 cancer cells than YNU-4a-YNU-4e, H-QL1a-H-QL1e, cisplatin (PDD), YNU-4g-YNU-4k, and H-QL3a-H-QL3c. Additionally, a colocalization assay analysis of YNU-4e and YNU-4f showed that these two ruthenium(II/III) compounds were subcellularly accumulated in the mitochondria and other regions of the cytoplasm, where they induce mitophagy, adenosine triphosphate (ATP) reduction, mitochondrial respiratory chain complex I/IV(RC1/RC4) inhibition, and mitochondrial dysfunction. Accordingly, compounds YNU-4a-YNU-4k can be regarded as mitophagy inductors for the eradication of cisplatin-resistant LC549 cancer cells.

Bis(8-hy-droxy-quinolinium) naphthalene-1,5-di-sulfonate tetra-hydrate.

The inter-action between 8-hy-droxy-quinoline (8HQ, C9H7NO) and naphthalene-1,5-di-sulfonic acid (H2NDS, C10H8O6S2) in aqueous media results in the formation of the salt hydrate bis-(8-hy-droxy-quinolinium) naphthalene-1,5-di-sulfonate tetra-hydrate, 2C9H8NO+·C10H6O6S2 2-·4H2O. The asymmetric unit comprises one protonated 8HQ+ cation, half of an NDS2- dianion symmetrically disposed around a center of inversion, and two water mol-ecules. Within the crystal structure, these components are organized into chains along the [010] and [10] directions through O-H⋯O and N-H⋯O hydrogen-bonding inter-actions, forming a di-periodic network parallel to (101). Additional stabilizing inter-actions such as C-H⋯O, C-H⋯π, and π-π inter-actions extend this arrangement into a tri-periodic network structure.

Synthesis, crystal structure and anti-cancer activity of the complex chlorido-(η2-ethyl-ene)(quinolin-8-olato-κ2N,O)platinum(II) by experimental and theoretical methods.

The complex [Pt(C9H6NO)Cl(C2H4)], (I), was synthesized and structurally characterized by ESI mass spectrometry, IR, NMR spectroscopy, DFT calculations and X-ray diffraction. The results showed that the deprotonated 8-hy-droxy-quinoline (C9H6NO) coordinates with the PtII atom via the N and O atoms while the ethyl-ene coordinates in the η2 manner and in the trans position compared to the coordinating N atom. The crystal packing is characterized by C-H⋯O, C-H⋯π, Cl⋯π and Pt⋯π inter-actions. Complex (I) showed high selective activity against Lu-1 and Hep-G2 cell lines with IC50 values of 0.8 and 0.4 µM, respectively, 54 and 33-fold more active than cisplatin. In particular, complex (I) is about 10 times less toxic to normal cells (HEK-293) than cancer cells Lu-1 and Hep-G2. Furthermore, the reaction of complex (I) with guanine at the N7 position was proposed and investigated using the DFT method. The results indicated that replacement of the ethyl-ene ligand with guanine is thermodynamically more favorable than the Cl ligand and that the reaction occurs via two consecutive steps, namely the replacement of ethyl-ene with H2O and the water with the guanine mol-ecule.

Complex formation of ML324, the histone demethylase inhibitor, with essential metal ions: Relationship between solution chemistry and anticancer activity.

N-(3-(dimethylamino)propyl-4-(8-hydroxyquinolin-6-yl)benzamide (ML324, HL) is a potent inhibitor of the iron-containing histone demethylase KDM4, a recognized potential target of cancer therapeutics. Herein, we report the proton dissociation and complex formation processes of ML324 with essential metal ions such as Fe(II), Fe(III), Cu(II) and Zn(II) using UV-visible, fluorescence, electron paramagnetic resonance and 1H NMR spectroscopic methods. The electrochemical behaviour of the copper and iron complexes was characterized by cyclic voltammetry and spectroelectrochemistry. The solid phase structure of ML324 analysed by X-ray crystallography is also provided. Based on the solution equilibrium data, ML324 is present in solution in H2L+ form with a protonated dimethylammonium moiety at pH 7.4, and this (N,O) donor bearing ligand forms mono and bis complexes with all the studied metal ions and the tris-ligand species is also observed with Fe(III). At pH 7.4 the metal binding ability of ML324 follows the order: Fe(II) < Zn(II) < Cu(II) < Fe(III). Complexation with iron resulted in a negative redox potential (E'1/2 = -145 mV vs. NHE), further suggesting that the ligand has a preference for Fe(III) over Fe(II). ML324 was tested for its anticancer activity in chemosensitive and resistant human cancer cells overexpressing the efflux pump P-glycoprotein. ML324 exerted similar activity in all tested cells (IC50 = 1.9-3.6 µM). Co-incubation and complexation of the compound with Cu(II) and Zn(II) had no impact on the cytotoxicity of ML324, whereas Fe(III) decreased the toxicity in a concentration-dependent manner, and this effect was more pronounced in the multidrug resistant cells.

Discovery of two novel bioactive algicidal substances from Brevibacillus sp. via metabolomics profiling and back-validation.

Identifying potent bacterial algicidal agents is essential for the development of effective, safe, and economically viable algaecides. Challenges in isolating and purifying these substances from complex secretions have impeded progress in this field. Metabolomics profiling, an efficient strategy for identifying metabolites, was pioneered in identifying bacterial algicidal substances in this study. Extracellular secretions from different generations of the algicidal bacterium Brevibacillus sp. were isolated for comprehensive analysis. Specifically, a higher algicidal efficacy was observed in the secretion from Generation 3 (G3) of Brevibacillus sp. compared to Generation 1 (G1). Subsequent metabolomics profiling comparing G3 and 1 revealed 83 significantly up-regulated metabolites, of which 9 were identified as potential algicidal candidates. Back-validation highlighted the potency of 4-acetamidobutanoic acid (4-ABC) and 8-hydroxyquinoline (8-HQL), which exhibited robust algicidal activity with 3d-EC50 values of 6.40 mg/L and 92.90 µg/L, respectively. These substances disrupted photosynthetic activity in M. aeruginosa by ceasing electron transfer in PSⅡ, like the impact exerted by Brevibacillus sp. secretion. These findings confirmed that 4-ABC and 8-HQL were the main algicidal components derived from Brevibacillus sp.. Thus, this study presents a streamlined strategy for identifying bacterial algicidal substances and unveils two novel and highly active algicidal substances. ENVIRONMENTAL IMPLICATION: Harmful cyanobacterial blooms (HCBs) pose significant environmental problems and health effects to humans and other organisms. The increasing frequency of HCBs has emerged as a pressing global concern. Bacterial-derived algicidal substances are expected to serve as effective, safe, and economically viable algaecides against HCBs. This study presents a streamlined strategy for identifying bacterial algicidal substances and unveils two novel substances (4-ABC and 8-HQL). These two substances demonstrate remarkable algicidal activity and disrupt the photosynthetic system in M. aeruginosa. They hold potential as prospective algaecides for addressing HCBs.

A Cu2+ fluorescent chemosensor suitable for quantitative detection of tyrosinase in potatoes over a wide pH range.

Cu2+ as an important trace element plays an essential role in various biologic processes due to the unique redox active nature. For this reason, much effort has been made to develop effective methods for Cu2+ detection. In this study, a novel structure fluorescent chemosensor, 1-(6-(((5-(5, 5-difluoro-1, 3, 7, 9-tetramethyl-5H-4λ4, 5λ4-dipyrrolo[1, 2-c:2', 1'-f][1, 3, 2] diazaborinin-10-yl)quinolin-8-yl)oxy)methyl)pyridin-2-yl)-N, N-bis(pyridin-2-ylmethyl)methanamine (1), was synthesized and characterized by 1H and 13C nuclear magnetic resonance spectroscopy, and electrospray ionization mass spectrometry. Sensor 1 showed an obviously "on-off" fluorescence response to Cu2+ with a 1:1 binding stoichiometry by UV-vis and fluorescence spectrophotometry. The detection limit of sensor 1 to Cu2+ was determined to be 1.9 µM, and the stable pH range for Cu2+ detection was from 3 to 13. Sensor 1 can be used for recognition and detection of tyrosinase in potatoes.

Determination of Lead in Bee Products by Solid Surface Fluorescence Using Complexation and Coacervation at Room Temperature Processes. An Environmental Friendly Methodology.

An accurate, economic and green methodology for Pb(II) monitoring in bee products is proposed. Complexed metal traces were preconcentrated on Nylon membranes using the coacervation phenomenon based on room temperature reaction between the cationic surfactant hexadecyltrimethylammonium bromide and the bile salt sodium cholate. The increase in solid surface fluorescence signal of dyes 8-hydroxyquinoleine and o-phenanthroline due to Pb(II) presence was used for the metal quantification. Experimental variables that influence on preconcentration step and fluorimetric sensitivity were optimized using uni-varied assays. Pb(II) concentration was determined on membranes by solid surface fluorescence at λem = 470 nm (λexc = 445 nm), using a solid sample holder. The calibration at optimal experimental conditions showed a LOD of 4.2 × 10-4 mg Kg-1 with a linear range of 1.28 × 10-3 mg Kg-1 to 8.73 mg Kg-1 and was successfully applied to Pb(II) quantification in different bee products produced in central west region of Argentina. The proposed methodology was applied to all samples after appropriate dilution. Accuracy methodology was evaluated by comparison of the obtained results with those found by ICP-MS, with percentage relative error under 8%. The precision was better than 0.0344 CV for Pb(II) determination.

Aluminium 8-Hydroxyquinolinate N-Oxide as a Precursor to Heterometallic Aluminium-Lanthanide Complexes.

A reaction in anhydrous toluene between the formally unsaturated fragment [Ln(hfac)3] (Ln3+ = Eu3+, Gd3+ and Er3+; Hhfac = hexafluoroacetylacetone) and [Al(qNO)3] (HqNO = 8-hydroxyquinoline N-oxide), here prepared for the first time from [Al(OtBu)3] and HqNO, affords the dinuclear heterometallic compounds [Ln(hfac)3Al(qNO)3] (Ln3+ = Eu3+, Gd3+ and Er3+) in high yields. The molecular structures of these new compounds revealed a dinuclear species with three phenolic oxygen atoms bridging the two metal atoms. While the europium and gadolinium complexes show the coordination number (CN) 9 for the lanthanide centre, in the complex featuring the smaller erbium ion, only two oxygens bridge the two metal atoms for a resulting CN of 8. The reaction of [Eu(hfac)3] with [Alq3] (Hq = 8-hydroxyquinoline) in the same conditions yields a heterometallic product of composition [Eu(hfac)3Alq3]. A recrystallization attempt from hot heptane in air produced single crystals of two different morphologies and compositions: [Eu2(hfac)6Al2q4(OH)2] and [Eu2(hfac)6(µ-Hq)2]. The latter compound can be directly prepared from [Eu(hfac)3] and Hq at room temperature. Quantum mechanical calculations confirm (i) the higher stability of [Eu(hfac)3Al(qNO)3] vs. the corresponding [Eu(hfac)3Alq3] and (ii) the preference of the Er complexes for the CN 8, justifying the different behaviour in terms of the Lewis acidity of the metal centre.

8-hydroxyquinoline-N-oxide copper(II)- and zinc(II)-phenanthroline and bipyridine coordination compounds: Design, synthesis, structures, and antitumor evaluation.

Fourteen novel tumor-targeting copper(II) and zinc(II) complexes, [Cu(ONQ)(QD1)(NO3)]·CH3OH (NQ3), [Cu(ONQ)(QD2)(NO3)] (NQ2), [Cu(NQ)(QD2)Cl] (NQ3), [Cu(ONQ)(QD1)Cl] (NQ4), [Cu(ONQ)(QD3)](NO3) (NQ5), [Cu(ONQ)(QD3)Cl] (NQ6), [Zn(ONQ)(QD4)Cl] (NQ7), [Zn(ONQ)(QD1)Cl] (NQ8), [Zn(ONQ)(QD5)Cl] (NQ9), [Zn(ONQ)(QD2)Cl] (NQ10), [Zn(ONQ)(QD6)Cl] (NQ11), [Zn(ONQ)(QD7)Cl] (NQ12), and [Zn(ONQ)(QD3)Cl] (NQ13) supported on 8-hydroxyquinoline-N-oxide (H-ONQ), 2,2'-dipyridyl (QD1), 5,5'-dimethyl-2,2'-bipyridyl (QD2), 1,10-phenanthroline (QD3), 4,4'-dimethoxy-2,2'-bipyridyl (QD4), 4,4'-dimethyl-2,2'-bipyridyl (QD5), 5-chloro-1,10-phenanthroline (QD6), and bathophenanthroline (QD7), were first synthesized and characterized using various spectroscopic techniques. Furthermore, NQ1-NQ13 exhibited higher antiproliferative activity and selectivity for cisplatin-resistant SK-OV-3/DDP tumor cells (CiSK3) compared to normal HL-7702 cells based on results obtained from the cell counting Kit-8 (CCK-8) assay. The complexation of copper(II) ion with QD2 and ONQ ligands resulted in an evident increase in the antiproliferation of NQ1-NQ6, with NQ6 exhibiting the highest antitumor potency against CiSK3 cells compared to NQ1-NQ5, H-ONQ, QD1-QD7, and NQ7-NQ13 as well as the reference cisplatin drug with an IC50 value of 0.17 ± 0.05 µM. Mechanistic studies revealed that NQ4 and NQ6 induced apoptosis of CiSK3 cells via mitophagy pathway regulation and adenosine triphosphate (ATP) depletion. Further, the differential induction of mitophagy decreased in the order of NQ6 > NQ4, which can be attributed to the major impact of the QD3 ligand with a large planar geometry and the Cl leaving group within the NQ6 complex. In summary, these results confirmed that the newly synthesized H-ONQ copper(II) and zinc(II) coordination metal compounds NQ1-NQ13 exhibit potential as anticancer drugs for cisplatin-resistant ovarian CiSK3 cancer treatment.

Organic LEDs Based on Bis(8-hydroxyquinoline) Zinc Derivatives with a Styryl Group.

For the first time, organic light-emitting diodes (OLEDs) based on bis(8-hydroxyquinoline) zinc with a styryl group (ZnStq) dispersed in poly(N-vinylcarbazole) matrix (ZnStq_R:PVK, where R = H, Cl, OCH3) were fabricated. The ZnStq_R:PVK films made via the spin-coating method were used as the active layer in these devices. The produced OLEDs showed strong electroluminescence with yellow emissions at 590, 587 and 578 nm for the ZnStq_H:PVK, ZnStq_Cl:PVK and ZnStq_OCH3:PVK, respectively. For all the studied thin films, the main photoluminescence emission bands were observed between 565 and 571 nm. The OLED with the ZnStq_OCH3:PVK layer with a narrow electroluminescence spectrum was found to have sufficient color purity to produce ultra-high-resolution displays with reduced power consumption (full width at half maximum of 59 nm, maximum brightness of 2244 cd/m2 and maximum current efficiency of 1.24 cd/A, with a turn-on voltage of 6.94 V and a threshold voltage of 7.35 V). To characterize the photophysical properties of the active layer, the ZnStq_R:PVK layers samples were additionally deposited on glass and silicon substrates. We found that the obtained results predestine ZnStq_R:PVK layers for use in the lighting industry in the future.