Structural and Electronic Control of the Bidentate 1-(2-pyridyl)benzotriazole Ligand in Copper Chemistry with Application to Catalysis in the A3 Coupling Reaction.

The hybrid bidentate 1-(2-pyridyl)benzotriazole (pyb) ligand was introduced into 3d transition metal catalysis. Specifically, [CuII (OTf)2 (pyb)2 ]⋅2 CH3 CN (1) enables the synthesis of a wide range of propargylamines by the A3 coupling reaction at room temperature in the absence of additives. Experimental and high-level theoretical calculations suggest that the bridging N atom of the ligand imposes exclusive trans coordination at Cu and allows ligand rotation, while the N atom of the pyridine group modulates charge distribution and flux, and thus orchestrates structural and electronic precatalyst control permitting alkyne binding with simultaneous activation of the C-H bond via a transient CuI species.

Solvent-Free Synthesis and Key Intermediate Isolation in Ni2Dy2 Catalyst Development in the Domino Ring-Opening Electrocyclization Reaction of Furfural and Amines.

A solvent-free methodology that yields trans-4,5-diaminocyclopent-2-enones, main domains of natural products and a variety of N-heterocycles, is described. The bimetallic catalyst [NiII2DyIII2L4(DMF)6] 2(OTf) 2(DMF) (1) promotes the domino reaction of furfural and amines, with loadings as low as 0.01%, under stirring or microwave-assisted conditions to afford the corresponding frameworks in very good to excellent yields. Crystallographic and theoretical studies shed light on the exclusive formation of the trans-diastereoisomers via a 4π-conrotatory electrocyclization process elucidating the key step in the catalytic process.

Cu(II) Coordination Polymers as Vehicles in the A3 Coupling.

A family of benzotriazole based coordination compounds, obtained in two steps and good yields from commercially available materials, formulated as [CuII(L1)2(MeCN)2]·2ClO4·MeCN (1), [CuII(L1)(NO3)2]·MeCN (2), [ZnII(L1)2(H2O)2]·2ClO4·2MeCN (3), [CuII(L1)2Cl2]2 (4), [CuII5(L1)2Cl10] (5), [CuII2(L1)4Br2]·4MeCN·CuII2Br6 (6), [CuII(L1)2(MeCN)2]·2BF4 (7), [CuII(L1)2(CF3SO3)2] (8), [ZnII(L1)2(MeCN)2]·2CF3SO3 (9), [CuII2(L2)4(H2O)2]·4CF3SO3·4Me2CO (10), and [CuII2(L3)4(CF3SO3)2]·2CF3SO3·Me2CO (11), are reported. These air-stable compounds were tested as homogeneous catalysts for the A3 coupling synthesis of propargylamine derivatives from aldehyde, amine, and alkyne under a noninert atmosphere. Fine tuning of the catalyst resulted in a one-dimensional (1D) coordination polymer (CP) (8) with excellent catalytic activity in a wide range of substrates, avoiding any issues that would inhibit its performance.

3d/4f Coordination Clusters as Cooperative Catalysts for Highly Diastereoselective Michael Addition Reactions.

Michael addition (MA) is one of the most well studied chemical transformation in synthetic chemistry. Here, we report the synthesis and crystal structures of a library of 3d/4f coordination clusters (CCs) formulated as [ZnII2YIII2L4(solv)X(Z)Y] and study their catalytic properties toward the MA of nitrostyrenes with barbituric acid derivatives. Each CC presents two borderline hard/soft Lewis acidic ZnII centers and two hard Lewis acidic YIII centers in a defect dicubane topology that brings the two different metals into a proximity of ∼3.3 Å. Density functional theory computational studies suggest that these tetrametallic CCs dissociate in solution to give two catalytically active dimers, each containing one 3d and one 4f metal that act cooperatively. The mechanism of catalysis has been corroborated via NMR, electron paramagnetic resonance, and UV-vis. The present work demonstrates for the first time the successful use of 3d/4f CCs as efficient and high diastereoselective catalysts in MA reactions.

Disruption of the Prostaglandin Metabolome and Characterization of the Pharmaceutical Exposome in Fish Exposed to Wastewater Treatment Works Effluent As Revealed by Nanoflow-Nanospray Mass Spectrometry-Based Metabolomics.

Fish can be exposed to a complex mixture of chemical contaminants, including pharmaceuticals, present in discharges of wastewater treatment works (WwTWs) effluents. There is little information on the effects of effluent exposure on fish metabolism, especially the small molecule signaling compounds which are the biological target of many pharmaceuticals. We applied a newly developed sensitive nanoflow-nanospray mass spectrometry nontargeted profiling technique to identify changes in the exposome and metabolome of roach (Rutilus rutilus) exposed to a final WwTWs effluent for 15 days. Effluent exposure resulted in widespread reduction (between 50% and 90%) in prostaglandin (PG) profiles in fish tissues and plasma with disruptions also in tryptophan/serotonin, bile acid and lipid metabolism. Metabolite disruptions were not explained by altered expression of genes associated with the PG or tryptophan metabolism. Of the 31 pharmaceutical metabolites that were detected in the effluent exposome of fish, 6 were nonsteroidal anti-inflammatory drugs but with plasma concentrations too low to disrupt PG biosynthesis. PGs, bile acids, and tryptophan metabolites are important mediators regulating a diverse array of physiological systems in fish and the identity of wastewater contaminants disrupting their metabolism warrants further investigation on their exposure effects on fish health.

Efficient Ni(II)2Ln(III)2 Electrocyclization Catalysts for the Synthesis of trans-4,5-Diaminocyclopent-2-enones from 2-Furaldehyde and Primary or Secondary Amines.

A series of heterometallic coordination clusters (CCs) [Ni(II)2Ln(III)2(L1)4Cl2(CH3CN)2] 2CH3CN [Ln = Y (1Y), Sm (1Sm), Eu (1Eu), Gd (1Gd), or Tb (1Tb)] were synthesized by the reaction of (E)-2-(2-hydroxy-3-methoxybenzylidene-amino)phenol) (H2L1) with NiCl2·6(H2O) and LnCl3·x(H2O) in the presence of Et3N at room temperature. These air-stable CCs can be obtained in very high yields from commercially available materials and are efficient catalysts for the room-temperature domino ring-opening electrocyclization synthesis of trans-4,5-diaminocyclopent-2-enones from 2-furaldehyde and primary or secondary amines under a non-inert atmosphere. Structural modification of the catalyst to achieve immobilization or photosensitivity is possible without deterioration in catalytic activity.

Solid-phase extraction and nanoflow liquid chromatography-nanoelectrospray ionization mass spectrometry for improved global urine metabolomics.

Global urine metabolomics is a rapidly expanding field with the potential to discover biomarkers of disease and exposure. To date, most methods focus on rapid sample preparation, using neat or diluted urine, together with high-throughput analyses, and are poorly suited for detection of low abundance metabolites present in urine samples. In this study, novel methods have been developed to analyze urine by splitless nanoflowUHPLC-nanoESI-TOFMS (nUHPLC-nESI-TOFMS) after preconcentration by solid-phase extraction (SPE), thus enabling significant improvements in analytical sensitivity and coverage of the urinary metabolome. In initial work, urine samples were extracted by both anion and cation exchange mixed-mode polymeric SPE cartridges and qualitatively compared with those using conventional sample preparations using UHPLC-ESI-TOFMS analyses. Compared with neat or diluted urine samples, SPE concentration of urine resulted in detection of additional metabolites including bile acids, lipids, pharmaceuticals, and markers of lifestyle, with little loss of other components of the metabolome. Analyses of SPE preparations by nUHPLC-nESI-TOFMS revealed excellent retention time repeatability with <1% coefficient of variation (CV) for 96% of analyzed peaks. The repeatability of the MS response was <30% CV for >79% of MS features in both negative and positive nESI modes. Compared with UHPLC-ESI-TOFMS, analysis by the nanoplatform enabled detection of signaling molecules important in disease processes including sex steroids, glucocorticoids, eicosanoids, and neurotransmitter metabolites. The significant improvement in sensitivity arising from use of splitless nUHPLC-nESI-TOFMS analyses of SPE-concentrated samples represents a step change in coverage of the urinary metabolome, thereby increasing the potential for biomarker discovery.

Heteronuclear 3 d/Dy(III) coordination clusters as catalysts in a domino reaction.

Three isoskeletal tetranuclear coordination clusters with general formula [M(II) 2 Dy(III) 2 L4 (EtOH)6 ](ClO4 )2 ⋅2 EtOH, (M=Co, 1; M=Ni, 2) and [Ni(II) 2 Dy(III) 2 L4 Cl2 (CH3 CN)2 ]⋅2 CH3 CN (3), have been synthesized and characterized. These air-stable compounds, and in particular 3, display efficient homogeneous catalytic behavior in the room-temperature synthesis of trans-4,5-diaminocyclopent-2-enones from 2-furaldehyde and primary or secondary amines under a non-inert atmosphere.

Neonicotinoid Residues in Wildflowers, a Potential Route of Chronic Exposure for Bees.

In recent years, an intense debate about the environmental risks posed by neonicotinoids, a group of widely used, neurotoxic insecticides, has been joined. When these systemic compounds are applied to seeds, low concentrations are subsequently found in the nectar and pollen of the crop, which are then collected and consumed by bees. Here we demonstrate that the current focus on exposure to pesticides via the crop overlooks an important factor: throughout spring and summer, mixtures of neonicotinoids are also found in the pollen and nectar of wildflowers growing in arable field margins, at concentrations that are sometimes even higher than those found in the crop. Indeed, the large majority (97%) of neonicotinoids brought back in pollen to honey bee hives in arable landscapes was from wildflowers, not crops. Both previous and ongoing field studies have been based on the premise that exposure to neonicotinoids would occur only during the blooming period of flowering crops and that it may be diluted by bees also foraging on untreated wildflowers. Here, we show that exposure is likely to be higher and more prolonged than currently recognized because of widespread contamination of wild plants growing near treated crops.

Sensitive determination of mixtures of neonicotinoid and fungicide residues in pollen and single bumblebees using a scaled down QuEChERS method for exposure assessment.

To accurately estimate exposure of bees to pesticides, analytical methods are needed to enable quantification of nanogram/gram (ng/g) levels of contaminants in small samples of pollen or the individual insects. A modified QuEChERS extraction method coupled with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) analysis was tested to quantify residues of 19 commonly used neonicotinoids and fungicides and the synergist, piperonyl butoxide, in 100 mg samples of pollen and in samples of individual bumblebees (Bombus terrestris). Final recoveries ranged from 71 to 102 % for most compounds with a repeatability of below 20 % for both pollen and bumblebee extracts spiked at 5 and 40 ng/g. The method enables the detection of all compounds at sub-ng/g levels in both matrices and the method detection limits (MDL) ranged from 0.01 to 0.84 ng/g in pollen and 0.01 to 0.96 ng/g in individual bumblebees. Using this method, mixtures of neonicotinoids (thiamethoxam, clothianidin, imidacloprid and thiacloprid) and fungicides (carbendazim, spiroxamine, boscalid, tebuconazole, prochloraz, metconazole, fluoxastrobin, pyraclostrobin and trifloxystrobin) were detected in pollens of field bean, strawberry and raspberry at concentrations ranging from MDL, and in some bees, the fungicides carbendazim, boscalid, tebuconazole, flusilazole and metconazole were present at concentrations between 0.80 to 30 ng/g. This new method allows the analysis of mixtures of neonicotinoids and fungicides at trace levels in small quantities of pollen and individual bumblebees and thus will facilitate exposure assessment studies.

Global metabolite profiling reveals transformation pathways and novel metabolomic responses in Solea senegalensis after exposure to a non-ionic surfactant.

Alcohol polyethoxylate (AEO) surfactants are widely used in household and industrial products, but the health effects arising from short-term exposure to sublethal concentrations are unknown. A metabolomic approach was used to investigate the biotransformation and effects of exposure to sublethal concentrations of hexaethylene glycol monododecylether (C12EO6) in juvenile sole, Solea senegalensis. After 5 days, C12EO6 was rapidly metabolized in the sole by oxidation, glucuronidation, and ethoxylate chain shortening. C12EO6 exposure at either 146 or 553 µg L(-1) resulted in significant metabolite disruption in liver and blood samples, including an apparent fold increase of >10(6) in the circulating levels of C24 bile acids and C27 bile alcohols, disturbance of glucocorticoid and lipid metabolism, and a 470-fold decrease in levels of the fatty acid transport molecule palmitoyl carnitine. Depuration resulted in rapid elimination of the surfactant and normalization of metabolites toward pre-exposure levels. Our findings show for the first time the ability of metabolomic analyses to discern effects of this AEO on metabolite homeostasis at exposure levels below its no effect concentrations for survival and reproduction in juvenile fish. The pronounced alteration in levels of liver metabolites, phospholipids, and glucocorticoids in S. senegalensis in response to surfactant exposure may indicate that this contaminant could potentially impact a number of health end points in fish.

The xenometabolome and novel contaminant markers in fish exposed to a wastewater treatment works effluent.

Organisms exposed to wastewater treatment works (WwTW) effluents accumulate complex mixtures of xenobiotics but there is a scarcity of information on the nature and impacts of these chemical mixtures. We applied metabolomics techniques as a novel approach to identify xenobiotics and their metabolites (the xenometabolome) that bioconcentrate in fish exposed to a WwTW effluent. Exposed juvenile rainbow trout (Oncorhynchus mykiss) accumulated surfactants, naphthols, chlorinated xylenols, and phenoxyphenols, chlorophenes, resin acids, mefenamic acid, oxybenzone, and steroidal alkaloids in the bile or plasma, and there were perturbations in the plasma concentrations of bile acids and lipids. Exposure of adult roach (Rutilus rutilus) to 50% or 100% concentrations of the same effluent resulted in dose-dependent increases in plasma concentrations of xenometabolites as well as cyprinol sulfate and taurocholic acid, lysophospholipids, and a decrease in sphingosine levels (a key component of cell membrane lipids). Our findings reveal the highly complex nature of xenobiotics accumulating in effluent-exposed fish, and the great potential of metabolomics for both identifying plasma marker (bio)chemicals for monitoring exposure to wastewater effluents, and for targeting studies on potential consequent impacts on fish health.

Defective iron homeostasis and hematological abnormalities in Niemann-Pick disease type C1.

Background: Niemann-Pick disease type C1 (NPC1) is a neurodegenerative lysosomal storage disorder characterized by the accumulation of multiple lipids in the late endosome/lysosomal system and reduced acidic store calcium. The lysosomal system regulates key aspects of iron homeostasis, which prompted us to investigate whether there are hematological abnormalities and iron metabolism defects in NPC1. Methods: Iron-related hematological parameters, systemic and tissue metal ion and relevant hormonal and proteins levels, expression of specific pro-inflammatory mediators and erythrophagocytosis were evaluated in an authentic mouse model and in a large cohort of NPC patients. Results: Significant changes in mean corpuscular volume and corpuscular hemoglobin were detected in Npc1 -/- mice from an early age. Hematocrit, red cell distribution width and hemoglobin changes were observed in late-stage disease animals. Systemic iron deficiency, increased circulating hepcidin, decreased ferritin and abnormal pro-inflammatory cytokine levels were also found. Furthermore, there is evidence of defective erythrophagocytosis in Npc1 -/- mice and in an in vitro NPC1 cellular model. Comparable hematological changes, including low normal serum iron and transferrin saturation and low cerebrospinal fluid ferritin were confirmed in NPC1 patients. Conclusions: These data suggest loss of iron homeostasis and hematological abnormalities in NPC1 may contribute to the pathophysiology of this disease.

Room-Temperature Cu(II) Radical-Triggered Alkyne C-H Activation.

A dimeric Cu(II) complex [Cu(II)2L2(µ2-Cl)Cl] (1) built from an asymmetric tridentate ligand (2-(((2-aminocyclohexyl)imino)methyl)-4,6-di-tert-butylphenol) and weakly coordinating anions has been synthesized and structurally characterized. In dichloromethane solution, 1 exists in a monomeric [Cu(II)LCl] (1') (85%)-dimeric (1) (15%) equilibrium, and cyclic voltammetry (CV) and electron paramagnetic resonance (EPR) studies indicate structural stability and redox retention. Addition of phenylacetylene to the CH2Cl2 solution populates 1' and leads to the formation of a transient radical species. Theoretical studies support this notion and show that the radical initiates an alkyne C-H bond activation process via a four-membered ring (Cu(II)-O···H-Calkyne) intermediate. This unusual C-H activation method is applicable for the efficient synthesis of propargylamines, without additives, within 16 h, at low loadings and in noncoordinating solvents including late-stage functionalization of important bioactive molecules. Single-crystal X-ray diffraction studies, postcatalysis, confirmed the framework's stability and showed that the metal center preserves its oxidation state. The scope and limitations of this unconventional protocol are discussed.

Shedding light on the use of Cu(ii)-salen complexes in the A3 coupling reaction.

One Cu(ii) complex, {Cu(ii)L} (1S), has been synthesised, in two high yielding steps under ambient conditions, and characterised by single-crystal X-Ray diffraction (SXRD), IR, UV-Vis, circular dichroism (CD), elemental analysis, thermogravimetric analysis (TGA) and electron spray ionization mass spectroscopy (ESI-MS). This air-stable compound enables the generation, at room temperature and in open-air, of twenty propargylamines, nine new, from secondary amines, aliphatic aldehydes and alkynes with a broad scope with yields up to 99%. Catalyst loadings can be as low as 1 mol%, while the recovered material retains its structural integrity and can be used up to 5 times without loss of its activity. Control experiments, SXRD, cyclic voltammetry and theoretical studies shed light on the mechanism revealing that the key to success is the use of phenoxido salen based ligands. These ligands orchestrate topological control permitting alkyne binding with concomitant activation of the C-H bond and simultaneously acting as a template temporarily accommodating the abstracted acetylenic proton, and continuously generating, via in situ formed radicals and a Single Electron Transfer (SET) mechanism, a transient Cu(i) active site to facilitate this transformation. The scope and limitations of this protocol are discussed and presented.

The potential of nanoflow liquid chromatography-nano electrospray ionisation-mass spectrometry for global profiling the faecal metabolome.

Faeces are comprised of a wide array of metabolites arising from the circulatory system as well as the human microbiome. A global metabolite analysis (metabolomics) of faecal extracts offers the potential to uncover new compounds which may be indicative of the onset of bowel diseases such as colorectal cancer (CRC). To date, faecal metabolomics is still in its infancy and the compounds of low abundance present in faecal extracts poorly characterised. In this study, extracts of faeces from healthy subjects were profiled using a sensitive nanoflow-nanospray LC-MS platform which resulted in highly repeatable peak retention times (<2% CV) and intensities (<15% CV). Analysis of the extracts revealed wide coverage of the faecal metabolome including detection of low abundant signalling compounds such as sex steroids and eicosanoids, alongside highly abundant pharmaceuticals and tetrapyrrole metabolites. A small pilot study investigating differences in metabolomics profiles of faecal samples obtained from 7 CRC, 25 adenomatous polyp and 26 healthy groups revealed that secondary bile acids, conjugated androgens, eicosanoids, phospholipids and an unidentified haem metabolite were potential classes of metabolites that discriminated between the CRC and control sample groups. However, much larger follow up studies are needed to confirm which components of the faecal metabolome are associated with actual CRC disease rather than dietary influences. This study reveals the potential of nanospray-nanoflow LC-MS profiling of faecal samples from large scale cohort studies for uncovering the role of the faecal metabolome in colorectal disease formation.

Copper(ii)-benzotriazole coordination compounds in click chemistry: a diagnostic reactivity study.

This diagnostic study aims to shed light on the catalytic activity of a library of Cu(ii) based coordination compounds with benzotriazole-based ligands. We report herein the synthesis and characterization of five new coordination compounds formulated as [CuII(L4)(MeCN)2(CF3SO3)2] (1), [CuII(L5)2(CF3SO3)2] (2), [CuII(L6)2(MeCN)(CF3SO3)]·(CF3SO3) (3), [CuII(L6)2(H2O)(CF3SO3)]·(CF3SO3)·2(Me2CO) (4), and [Cu(L1)2(L1')2(CF3SO3)2]2·4(CF3SO3)·8(Me2CO) (5), derived from similar nitrogen-based ligands. The homogeneous catalytic activity of these compounds along with our previously reported coordination compounds (6-13), derived from similar ligands, is tested against the well-known Cu(i)-catalysed azide-alkyne cycloaddition reaction. The optimal catalyst [CuII(L1)2(CF3SO3)2] (10) activates the reaction to afford 1,4-disubstituted 1,2,3-triazoles with yields up to 98% and without requiring a reducing agent. Various control experiments are performed to optimize the method and examine parameters such as ligand variation, metal coordination geometry and environment, in order to elucidate the behaviour of the catalytic system.

Dinucleating Schiff base ligand in Zn/4f coordination chemistry: synthetic challenges and catalytic activity evaluation.

Four Zn/4f polynuclear coordination clusters (PCCs) formulated as [ZnII2DyIII2L2(CO3)2(NO3)2] (1), [ZnIIYIIIL(NO3)2(o-van) (MeOH)] (MeOH) [2 (MeOH)] and [ZnIILnIIIL(NO3)2Cl(EtOH)] where Ln is Dy (3) and Y (4) and where H2L is the dinucleating Schiff base ligand N,N'-bis(3-methoxysalicylidene)cyclohexane-1,2-diamine and o-van is ortho-vanillin, were prepared and fully characterised for the first time. These air-stable heterometallic PCCs, obtained in high yields from commercially available materials, were shown to remain stable in solution in their dinuclear [ZnIILnIIIL] form. Their catalytic activity was evaluated in various catalytic transformations including the Friedel-Crafts alkylation of 2-acyl imidazoles with indoles.

Nanoflow-Nanospray Mass Spectrometry Metabolomics Reveals Disruption of the Urinary Metabolite Profiles of HIV-Positive Patients on Combination Antiretroviral Therapy.

BACKGROUND: The use of combination antiretroviral therapy (cART) has substantially improved the outlook for patients with HIV infection. However, lifelong exposure to cART is also associated with adverse metabolic changes and an enhanced risk of renal, hepatic, and cardiovascular dysfunction. This study investigated disruptions of the urinary metabolome of cART-exposed patients, thereby furthering our understanding of some of the side effects of pharmaceutical intervention. METHODS: HIV-positive patients were recruited from an HIV clinic and divided into cART-naive and cART-exposed groups. HIV-negative patients were recruited from a sexual health clinic. All 89 subjects were white males. Targeted biochemistry analyses were performed on plasma samples. Urine samples were collected after an overnight fast and analyzed with a highly sensitive untargeted metabolomic method using nanoflow/nanospray liquid chromatography-time-of-flight mass spectrometry. Data sets were analyzed using projection modeling to detect metabolite markers of cART exposure. RESULTS: Metabolites or parent compounds of all cART drugs were detected in urine extracts of all but one of the cART-exposed patients confirming adherence to the pharmaceutical regimen. Analysis of urine samples from patients on cART revealed significant reductions in selected bile acids, lipid, nucleoside, and androgen metabolites. However, plasma concentrations of free or conjugated testosterone remained unchanged indicating possible disruption of androgen transport or excretion in urine of patients on cART. CONCLUSIONS: Discovery-based metabolomics reveals the potential to identify novel markers of cART intervention and metabolite disruption in HIV-positive patients, which may enable investigation of the efficacy, compliance, and side effects of these pharmaceutical mixtures to be investigated.