Curly Kale (Brassica oleracea var. Sabellica L.) Biofortified with 5,7-Diiodo-8-quinolinol: The Influence of Heat Treatment on Iodine Level, Macronutrient Composition and Antioxidant Content.

Many disorders are a result of an inadequate supply of macronutrients and micronutrients in the diet. One such element is iodine. This study used curly kale (Brassica oleracea var. Sabellica L.) biofortified with the 5,7-diiodo-8-quinolinol iodine compound. The effect of the heat treatment on the chemical composition of the curly kale was studied. In addition, iodine bioavailability was evaluated in in vivo studies. Our investigation showed that iodine loss depends on the type of heat treatment as well as on the variety of kale. Curly kale biofortified with iodoquinoline had significantly higher iodine levels after thermal processing (steaming, blanching, boiling) than the vegetable biofortified with KIO3. Generally, steaming was the best thermal processing method, as it contributed to the lowest iodine loss in curly kale. The red variety of kale, 'Redbor F1', showed a better iodine stability during the heat treatment than the green variety, 'Oldenbor F1'. The thermal treatment also significantly affected the dry matter content and the basic chemical composition of the tested varieties of the 5,7-diI-8-Q biofortified kale. The steaming process caused a significant increase in total carbohydrates, fiber, protein and crude fat content ('Oldenbor F1', 'Redbor F1'), and antioxidant activity ('Oldenbor F1'). On the other hand, boiling caused a significant decrease, while steaming caused a significant increase, in protein and dry matter content ('Oldenbor F1', 'Redbor F1'). The blanching process caused the smallest significant decrease in ash compared to the other thermal processes used ('Oldenbor F1'). A feeding experiment using Wistar rats showed that iodine from the 5,7-diI-8-Q biofortified kale has a higher bioavailability than that from the AIN-93G diet. A number of promising results have been obtained, which could form the basis for further research.

Spatio-temporal biodistribution of 89Zr-oxine labeled huLym-1-A-BB3z-CAR T-cells by PET imaging in a preclinical tumor model.

Quantitative in vivo monitoring of cell biodistribution offers assessment of treatment efficacy in real-time and can provide guidance for further optimization of chimeric antigen receptor (CAR) modified cell therapy. We evaluated the utility of a non-invasive, serial 89Zr-oxine PET imaging to assess optimal dosing for huLym-1-A-BB3z-CAR T-cell directed to Lym-1-positive Raji lymphoma xenograft in NOD Scid-IL2Rgammanull (NSG) mice. In vitro experiments showed no detrimental effects in cell health and function following 89Zr-oxine labeling. In vivo experiments employed simultaneous PET/MRI of Raji-bearing NSG mice on day 0 (3 h), 1, 2, and 5 after intravenous administration of low (1.87 ± 0.04 × 106 cells), middle (7.14 ± 0.45 × 106 cells), or high (16.83 ± 0.41 × 106 cells) cell dose. Biodistribution (%ID/g) in regions of interests defined over T1-weighted MRI, such as blood, bone, brain, liver, lungs, spleen, and tumor, were analyzed from PET images. Escalating doses of CAR T-cells resulted in dose-dependent %ID/g biodistributions in all regions. Middle and High dose groups showed significantly higher tumor %ID/g compared to Low dose group on day 2. Tumor-to-blood ratios showed the enhanced extravascular tumor uptake by day 2 in the Low dose group, while the Middle dose showed significant tumor accumulation starting on day 1 up to day 5. From these data obtained over time, it is apparent that intravenously administered CAR T-cells become trapped in the lung for 3-5 h and then migrate to the liver and spleen for up to 2-3 days. This surprising biodistribution data may be responsible for the inactivation of these cells before targeting solid tumors. Ex vivo biodistributions confirmed in vivo PET-derived biodistributions. According to these studies, we conclude that in vivo serial PET imaging with 89Zr-oxine labeled CAR T-cells provides real-time monitoring of biodistributions crucial for interpreting efficacy and guiding treatment in patient care.

Biodegradable pH-responsive micelles loaded with 8-hydroxyquinoline glycoconjugates for Warburg effect based tumor targeting.

Biodegradable triblock copolymer poly(ethylene glycol)-b-polycarbonate-b-oligo([R]-3-hydroxybutyrate) was prepared via metal-free ring-opening polymerization of ketal protected six-membered cyclic carbonate followed by esterification with bacterial oligo([R]-3-hydroxybutyrate) (oPHB). Amphiphilic triblock copolymer self-organizes into micelles with a diameter of ~25 nm. Acid-triggered hydrolysis of ketal groups to two hydroxyl groups causes an increase in hydrophilicity of the hydrophobic micelle core, resulting in the micelles swell and drug release. oPHB was added as core-forming block to increase the stability of prepared micelles in all pH (7.4, 6.4, 5.5) studied. Doxorubicin and 8-hydroxyquinoline glucose- and galactose conjugates were loaded in the micelles. In vitro drug release profiles in PBS buffers with different pH showed that a small amount of loaded drug was released in PBS at pH 7.4, while the drug was released much faster at pH 5.5. MTT assay showed that the blank micelles were non-toxic to different cell lines, while glycoconjugates-loaded micelles, showed significantly increased ability to inhibit the proliferation of MCF-7 and HCT-116 cells compared to free glycoconjugates. The glycoconjugation of anti-cancer drugs and pH-responsive nanocarriers have separately shown great potential to increase the tumor-targeted drug delivery efficiency. The combination of drug glycoconjugation and the use of pH-responsive nanocarrier opens up new possibilities to develop novel strategies for efficient tumor therapy.

Synthesis of Novel 8-Hydroxyquinoline Derivatives through Mannich Reaction and their Biological Evaluation as Potential Immunomodulatory Agents.

BACKGROUND: In continuation of our work on Mannich reaction on 8-hydroxyquinoline, fifteen different combinations of aromatic aldehydes and aniline were subjected to Mannich reaction from which twelve products (eight Mannich bases, two imines and two intramolecularly cyclized products with benzofuranone skeleton) were obtained. Among them six compounds (1, 2, 6, 8, 9 and 12) are the new compounds. The structures of the compounds were characterized by UV, IR, MS and 1H NMR. METHODS: The compounds were tested for the inhibition of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and Interleukin-1ß (IL-1ß) at a concentration of 25 µg/mL. The cytokines were produced by THP-1 cells differentiated with PMA for 24hrs and stimulated with LPS for 4 hrs and supernatant were analyzed through ELISA technique. RESULTS AND DISCUSSION: Compounds 1-5, 8 and 9 inhibited the production of TNF-α and IL-1ß. Compounds 1, 3, and 8 exerted potent inhibitions of TNF-α with 71%, 71%, and 83% inhibition, respectively. Compounds 1 and 8 significantly inhibited the production of IL-1ß with 64% and 78% inhibition, respectively. CONCLUSION: Compounds 1 and 8 significantly inhibited the production of IL-1ß with 64% and 78% inhibition, respectively. Notably compound 8 showed the most potent inhibition of these cytokines. Additionally, the effect of compounds on viability of THP-1 cells was also evaluated. Moreover, molecular docking was carried out to study the mechanism of inhibition of TNF-α production.

Design and synthesis of fluorescent activity probes for protein phosphatases.

Protein phosphatases act in concert with protein kinases to regulate and maintain the phosphoproteome. However, the catalog of chemical tools to directly monitor the enzymatic activity of phosphatases has lagged behind their kinase counterparts. In this chapter, we provide protocols for repurposing the phosphorylation-sensitive sulfonamido-oxine fluorophore known as Sox to afford direct activity probes for phosphatases. With validated activity probes in-hand, inhibitor screens can be conducted with recombinant enzyme and the role of phosphatases in cell signaling can be investigated in unfractionated cell lysates.

Microbiota Metabolism Promotes Synthesis of the Human Ah Receptor Agonist 2,8-Dihydroxyquinoline.

The aryl hydrocarbon receptor (AHR) is a major regulator of immune function within the gastrointestinal tract. Resident microbiota are capable of influencing AHR-dependent signaling pathways via production of an array of bioactive molecules that act as AHR agonists, such as indole or indole-3-aldehyde. Bacteria produce a number of quinoline derivatives, of which some function as quorum-sensing molecules. Thus, we screened relevant hydroxyquinoline derivatives for AHR activity using AHR responsive reporter cell lines. 2,8-Dihydroxyquinoline (2,8-DHQ) was identified as a species-specific AHR agonist that exhibits full AHR agonist activity in human cell lines, but only induces modest AHR activity in mouse cells. Additional dihydroxylated quinolines tested failed to activate the human AHR. Nanomolar concentrations of 2,8-DHQ significantly induced CYP1A1 expression and, upon cotreatment with cytokines, synergistically induced IL6 expression. Ligand binding competition studies subsequently confirmed 2,8-DHQ to be a human AHR ligand. Several dihydroxyquinolines were detected in human fecal samples, with concentrations of 2,8-DHQ ranging between 0 and 3.4 pmol/mg feces. Additionally, in mice the microbiota was necessary for the presence of DHQ in cecal contents. These results suggest that microbiota-derived 2,8-DHQ would contribute to AHR activation in the human gut, and thus participate in the protective and homeostatic effects observed with gastrointestinal AHR activation.

Klebsiella oxytoca enterotoxins tilimycin and tilivalline have distinct host DNA-damaging and microtubule-stabilizing activities.

Establishing causal links between bacterial metabolites and human intestinal disease is a significant challenge. This study reveals the molecular basis of antibiotic-associated hemorrhagic colitis (AAHC) caused by intestinal resident Klebsiella oxytoca Colitogenic strains produce the nonribosomal peptides tilivalline and tilimycin. Here, we verify that these enterotoxins are present in the human intestine during active colitis and determine their concentrations in a murine disease model. Although both toxins share a pyrrolobenzodiazepine structure, they have distinct molecular targets. Tilimycin acts as a genotoxin. Its interaction with DNA activates damage repair mechanisms in cultured cells and causes DNA strand breakage and an increased lesion burden in cecal enterocytes of colonized mice. In contrast, tilivalline binds tubulin and stabilizes microtubules leading to mitotic arrest. To our knowledge, this activity is unique for microbiota-derived metabolites of the human intestine. The capacity of both toxins to induce apoptosis in intestinal epithelial cells-a hallmark feature of AAHC-by independent modes of action, strengthens our proposal that these metabolites act collectively in the pathogenicity of colitis.

Optimization of 8-Hydroxyquinolines as Inhibitors of Catechol O-Methyltransferase.

A series of 8-hydroxy quinolines were identified as potent inhibitors of catechol O-methyltransferase (COMT) with selectivity for the membrane-bound form of the enzyme. Small substituents at the 7-position of the quinoline were found to increase metabolic stability without sacrificing potency. Compounds with good pharmacokinetics and brain penetration were identified and demonstrated in vivo modulation of dopamine metabolites in the brain. An X-ray cocrystal structure of compound 21 in the S-COMT active site shows chelation of the active site magnesium similar to catechol-based inhibitors. These compounds should prove useful for treatment of many neurological and psychiatric conditions associated with compromised cortical dopamine signaling.

Direct and Continuous Measurement of Phospholipase D Activities Using the Chelation-Enhanced Fluorescence Property of 8-Hydroxyquinoline.

Phospholipase D (PLD) hydrolyzes phospholipids to form phosphatidic acid (PA) and the corresponding headgroup. To date, PLD has been linked to several pathologies, such as cancer, making this enzyme an important therapeutic target. However, most PLD assays developed so far are either discontinuous or based on the indirect determination of choline released upon phosphatidylcholine (PC) hydrolysis. Therefore, we designed a PLD assay that is based on the chelation-enhanced fluorescence property of 8-hydroxyquinoline. This assay exhibits a strong fluorescence signal upon Ca2+ complexation with the PLD-generated PA and is not limited to PC as the substrate but allows the use of natural phospholipids with various headgroups. Besides, this easy-to-handle assay allows to monitor prokaryotic and eukaryotic PLD activities in a continuous way and on a microplate scale.

PET of Adoptively Transferred Chimeric Antigen Receptor T Cells with 89Zr-Oxine.

Chimeric antigen receptor (CAR) T cell therapy is a promising clinical approach for reducing tumor progression and prolonging patient survival. However, improvements in both the safety and the potency of CAR T cell therapy demand quantitative imaging techniques to determine the distribution of cells after adoptive transfer. The purpose of this study was to optimize 89Zr-oxine labeling of CAR T cells and evaluate PET as a platform for imaging adoptively transferred CAR T cells. Methods: CAR T cells were labeled with 0-1.4 MBq of 89Zr-oxine per 106 cells and assessed for radioactivity retention, viability, and functionality. In vivo trafficking of 89Zr-oxine-labeled CAR T cells was evaluated in 2 murine xenograft tumor models: glioblastoma brain tumors with intracranially delivered IL13Rα2-targeted CAR T cells, and subcutaneous prostate tumors with intravenously delivered prostate stem cell antigen (PSCA)-targeted CAR T cells. Results: CAR T cells were efficiently labeled (75%) and retained more than 60% of the 89Zr over 6 d. In vitro cytokine production, migration, and tumor cytotoxicity, as well as in vivo antitumor activity, were not significantly reduced when labeled with 70 kBq/106 cells. IL13Rα2-CAR T cells delivered intraventricularly were detectable by PET for at least 6 d throughout the central nervous system and within intracranial tumors. When intravenously administered, PSCA-CAR T cells also showed tumor tropism, with a 9-fold greater tumor-to-muscle ratio than for CAR-negative T cells. Conclusion:89Zr-oxine can be used for labeling and imaging CAR T cells while maintaining cell viability and function. On the basis of these studies, we conclude that 89Zr-oxine is a clinically translatable platform for real-time assessment of cell therapies.

Highly sensitive gold nanoparticles-based optical sensing of DNA hybridization using bis(8-hydroxyquinoline-5-solphonate)cerium(III) chloride as a novel fluorescence probe.

A simple and sensitive method for the detection of DNA hybridization in a homogeneous format was developed, using bis(8-hydroxyquinoline-5-solphonate)cerium(III) chloride (Ce(QS)2Cl) as a novel fluorescent probe. The method is based on fluorescence quenching by gold nanoparticles used as both nanoscafolds for the immobilization of the probe DNA sequence, which is related to Alicyclobacillus acidophilus strain TA-67 16S ribosomal RNA, and nanoquenchers of the Ce(QS)2Cl probe. The probe DNA-functionalized GNPs were synthesized by derivatizing the colloidal gold nanoparticles solution with 3-thiolated 16-base oligonucleotides. Addition of sequence-specific target DNAs (16 bases) into the mixture containing probe DNA-functionalized GNPs and fluorescent probe lead to the quenching of Ce(QS)2Cl fluorescence at 360 nm (λex=270 nm), due to DNA hybridization, the resulting quenched intensity being proportional to the concentration of target DNA. Under optimal conditions of pH 7.4 and Ce(QS)2Cl concentration of 1.0 × 10(-7) M, the linear dynamic range found to be 1.0 × 10(-10)-3.0 × 10(-8) M DNA, with a limit of detection of 7.0 × 10(-11) M. The interaction mechanism for the binding of Ce(QS)2Cl to DNA was studied in detail, and results proved that the interaction mode between Ce(QS)2Cl and DNA is groove binding, with a binding constant of 1.0 × 10(5) M(-1).

Targeting mitochondrial metal dyshomeostasis for the treatment of neurodegeneration.

Mitochondrial impairment and metal dyshomeostasis are suggested to be associated with many neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis and Friedreich's ataxia. Treatments aimed at restoring metal homeostasis are highly effective in models of these diseases, and clinical trials hold promise. However, in general, the effect of these treatments on mitochondrial metal homeostasis is unclear, and the contribution of mitochondrial metal dyshomeostasis to disease pathogenesis requires further investigation. This review describes the role of metals in mitochondria in health, how mitochondrial metals are disrupted in neurodegenerative diseases, and potential therapeutics aimed at restoring mitochondrial metal homeostasis and function.

Investigations into the bovine serum albumin binding and fluorescence properties of Tb (III) complex of a novel 8-hydroxyquinoline ligand.

A novel ligand, 2-methyl-6-(8-quinolinyl)-dicarboxylate pyridine (L), and its corresponding Tb (III) complex, Na4Tb(L)2Cl4·3H2O, were successfully prepared and characterized. The luminescence spectra showed that the ligand L was an efficient sensitizer for Tb (III) luminescence. The interaction of the complex with bovine serum albumin (BSA) was investigated through fluorescence spectroscopy under physiological conditions. The Stern-Volmer analysis indicated that the fluorescence quenching was resulted from static mechanism. The binding sites (n) approximated 1.0 and this meant that interaction of Na4Tb(L)2Cl4·3H2O with BSA had single binding site. The results showed van der Waals interactions and hydrogen bonds played major roles in the binding reaction. Furthermore, circular dichroism (CD) spectra indicated that the conformation of BSA was changed.

Metallomics for drug development: serum protein binding and analysis of an anticancer tris(8-quinolinolato)gallium(III) drug using inductively coupled plasma mass spectrometry.

The application of an inductively coupled plasma mass spectrometry (ICP-MS) assay for quantifying in vitro binding of a gallium-based anticancer drug, tris(8-quinolinolato)gallium(III), to serum albumin and transferrin and in human serum is described. The distribution of the drug between the protein-rich and protein-free fractions was assessed via ICP-MS measurement of total gallium in ultrafiltrates. Comparative kinetic studies revealed that the drug exhibits a different reactivity toward individual proteins. While the maximum possible binding to albumin (~10%) occurs practically immediately, interaction with transferrin has a step-like character and the equilibrium state (with more than 50% binding) is reached for about 48 h. Drug transformation into the bound form in serum, also very fast, results in almost quantitative binding (~95%). The relative affinity of protein-drug binding was characterized in terms of the association constants ranging from 10(3) to 10(4)M(-1). In order to further promote clinical testing of the gallium drug, the ICP-MS method was applied for direct quantification of gallium in human serum spiked with the drug. The detection limit for gallium was found to be as low as 20 ng L(-1). The repeatability was better than 8% (as RSD) and the achieved recoveries were in the range 99-103%.

Pollutant-induced modulation in conformation and ß-lactamase activity of human serum albumin.

Structural changes in human serum albumin (HSA) induced by the pollutants 1-naphthol, 2-naphthol and 8-quinolinol were analyzed by circular dichroism, fluorescence spectroscopy and dynamic light scattering. The alteration in protein conformational stability was determined by helical content induction (from 55 to 75%) upon protein-pollutant interactions. Domain plasticity is responsible for the temperature-mediated unfolding of HSA. These findings were compared to HSA-hydrolase activity. We found that though HSA is a monomeric protein, it shows heterotropic allostericity for ß-lactamase activity in the presence of pollutants, which act as K- and V-type non-essential activators. Pollutants cause conformational changes and catalytic modifications of the protein (increase in ß-lactamase activity from 100 to 200%). HSA-pollutant interactions mediate other protein-ligand interactions, such as HSA-nitrocefin. Therefore, this protein can exist in different conformations with different catalytic properties depending on activator binding. This is the first report to demonstrate the catalytic allostericity of HSA through a mechanistic approach. We also show a correlation with non-microbial drug resistance as HSA is capable of self-hydrolysis of ß-lactam drugs, which is further potentiated by pollutants due to conformational changes in HSA.

Gluconjugates of 8-hydroxyquinolines as potential anti-cancer prodrugs.

8-Hydroxyquinolines are systems of great interest in the field of inorganic and bioinorganic chemistry. They are metal-binding compounds and are known to exhibit a variety of biological activities, such as antibacterial and anticancer activities. Among these systems, clioquinol has been the focus of a renewed interest in recent years. In this scenario, we synthesized and characterized the new clioquinol glucoconjugate, 5-chloro-7-iodo-8-quinolinyl-ß-D-glucopyranoside in order to compare this system to that of clioquinol. We also synthesized, 8-quinolinyl-ß-D-glucopyranoside, an 8-hydroxyquinoline glucoconjugate. The reason for the development of glucoconjugates is the glucose avidity, and the over-expression of glucose transporters in cancer cells. Here we demonstrate that glycoconjugates are cleaved in vitro by ß-glucosidase and these systems exhibit antiproliferative activity against different tumor cell lines in the presence of copper(II) ions.

Enabling lead discovery for histone lysine demethylases by high-throughput RapidFire mass spectrometry.

A high-throughput RapidFire mass spectrometry assay is described for the JMJD2 family of Fe(2+), O(2), and α-ketoglutarate-dependent histone lysine demethylases. The assay employs a short amino acid peptide substrate, corresponding to the first 15 amino acid residues of histone H3, but mutated at two positions to increase assay sensitivity. The assay monitors the direct formation of the dimethylated-Lys9 product from the trimethylated-Lys9 peptide substrate. Monitoring the formation of the monomethylated and des-methylated peptide products is also possible. The assay was validated using known inhibitors of the histone lysine demethylases, including 2,4-pyridinedicarboxylic acid and an α-ketoglutarate analogue. With a sampling rate of 7 s per well, the RapidFire technology permitted the single-concentration screening of 101 226 compounds against JMJD2C in 10 days using two instruments, typically giving Z' values of 0.75 to 0.85. Several compounds were identified of the 8-hydroxyquinoline chemotype, a known series of inhibitors of the Lys9-specific histone demethylases. The peptide also functions as a substrate for JMJD2A, JMJD2D, and JMJD2E, thus enabling the development of assays for all 3 enzymes to monitor progress in compound selectivity. The assay represents the first report of a RapidFire mass spectrometry assay for an epigenetics target.

In vivo tracking of 111In-oxine labeled mesenchymal stem cells following infusion in patients with advanced cirrhosis.

BACKGROUND: Several animal and few human studies suggest the beneficial role of bone marrow mesenchymal stem cells (MSCs) in liver cirrhosis. However, little is known about the fate of MSCs after infusion in cirrhotic patients. We evaluated stem cell biodistribution after peripheral infusion of MSCs in four cirrhotic patients. METHODS: After three passages of MSCs, the patients received a total of 250-400×10(6) cells, of which only 50% of the cells were labeled. Specific activities of 0.21-0.67 MBq/10(6) cells were maintained for the injected labeled MSCs. Planar whole-body acquisitions (anterior/posterior projections) were acquired immediately following infusion as well as at 2 h, 4 h, 6 h, 24 h, 48 h, 7th and 10th days after cell infusion. RESULTS: After intravenous infusion, the radioactivity was first observed to accumulate in the lungs. During the following hours to days, the radioactivity gradually increased in the liver and spleen, with spleen uptake exceeding that in the liver in all patients. Region-of-interest analysis showed that the percentage of cells homing to the liver (following decay and background corrections and geometric mean calculation) increased from 0.0%-2.8% at immediately post-infusion images to 13.0-17.4% in 10th-day post-infusion. Similarly, the residual activities in the spleen increased from 2.0%-10.2% at immediately post-infusion images to 30.1%-42.2% in 10th-day post-infusion. During the same period, the residual activities in the lungs decreased from 27.0-33.5% to 2.0-5.4%. CONCLUSION: The infusion of MSCs labeled with (111)In-oxine through a peripheral vein is safe in cirrhosis. Cell labeling with (111)In-oxine is a suitable method for tracking MSC distribution after infusion.

Solvent dependent fluorescent properties of a 1,2,3-triazole linked 8-hydroxyquinoline chemosensor: tunable detection from zinc(II) to iron(III) in the CH3CN/H2O system.

A triazole-containing 8-hydroxyquinoline (8-HQ) ether 2 was efficiently synthesized in two steps from the "click" strategy. Compound 2 gave a strong fluorescence (Φ = 0.21) in nonprotic solvent like CH(3)CN, and a weak fluorescence (Φ = 0.06) in protic solvent like water. In water, a more than 100 nm red shift of the fluorescence maximum was observed for compound 2 in comparison with that in CH(3)CN. This fluorescence difference may be attributed to the intermolecular photoinduced proton transfer (PPT) process involving the protic solvent water molecules. Similarly, this intermolecular PPT process was also observed in the high-water-content CH(3)CN aqueous solution (e.g., CH(3)CN/H(2)O = 5/95, v/v). The water content in the CH(3)CN/H(2)O binary solvent mixture greatly affected the fluorescence intensity (e.g., Φ = 0.06 and 0.25 when CH(3)CN/H(2)O = 5/95 and 95/5, v/v, respectively) and emission wavelength. Using this interesting property, by simple variation of the water content in the CH(3)CN aqueous solution, compound 2 was tuned from a selective "turn-on" fluorescent sensor for Zn(2+) (CH(3)CN/H(2)O = 5/95, v/v) to a ratiometric one for Zn(2+) and a selective "turn-off" one for Fe(3+) (CH(3)CN/H(2)O = 95/5, v/v) over a wide range of pH value. In high-water-content (CH(3)CN/H(2)O = 5/95, v/v) aqueous solution compound 2 shows a selective "turn-on" response toward Zn(2+), with a 10-fold enhancement in the fluorescence intensity at 428 nm and a 62 nm blue shift of the emission maximum (490 to 428 nm) due to the inhibition of intermolecular PPT process upon chelating with Zn(2+). However, in a less polar solvent (CH(3)CN/H(2)O = 95/5, v/v) in which compound 2 has high fluorescence (quantum yield =0.25), it shows a ratiometric response toward Zn(2+), with a continuous decrease of the fluorescence intensity at 399 nm and an increase at 423 nm. More interestingly, in this case, it also exhibits a very sensitive, selective, and ratiometric fluorescence quenching in the presence of Fe(3+), with an 81 nm red shift of the emission maximum (399 to 480 nm) in a wide range of pH through a metal ligand charge transfer (MLCT) effect.

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.