Ligand Copper Research Articles

Multifunctional coordination polymers based on copper(i) and mercaptonicotinic ligands: synthesis, and structural, optical and electrical characterization.

Three new coordination polymers (CPs) named [Cu(6mna)]n (CP1), [CuCl(H6mna)(H2O)0.33]n (CP2), and {[(CuI)2H2dtdn].MeCN}n (CP3), (H6mna = 6-mercaptonicotinic acid, and H2dtdn = 6,6'-dithiodinicotinic acid) have been synthesized and their structures determined by single-crystal X-ray diffraction. Complexes 1 and 3 are 2D-CPs while complex 2 is a 1D-CP. The optical properties of these complexes have been evaluated in the solid state, at room temperature and at 77 K, and compared with those of the starting ligands. The electrical conductivity of CPs 1-3 has been evaluated and their thermal stabilities have been studied. CP2 shows an interesting crystal arrangement, where the connection between the ligand and the copper forms a channel-like structure characterized by an intrinsic disorder. Crystal data collected at low temperatures for this complex revealed minor structural changes in the CuCu distances and Cu-S-Cu angles along the chain, excluding phase transition. In CP1, the N and S atoms are involved in metal coordination bonds giving rise to a 2D coordination polymer. In CP3, the Cu-I bonds compose double ladder-like structures, bridged by H2dtdn ligands. The electrical conductivities of CPs 1-3 suggest their semiconductive behavior.

Recent advances in copper-catalysed radical-involved asymmetric 1,2-difunctionalization of alkenes.

The radical-involved 1,2-difunctionalization of alkenes has developed into a robust tool for preparation of complex organic molecules. Despite significant advances in this area, the catalytic asymmetric version still remains a challenging task mainly due to the difficulty in the stereocontrol of the highly reactive radical intermediates. Recently, owing to the good single-electron transfer ability and coordination with chiral ligands of copper catalysts, remarkable achievements in radical-involved asymmetric alkene difunctionalization have been made via synergistic combination of copper and chiral ligands. This tutorial review highlights the recent progress in copper-catalysed radical-involved asymmetric 1,2-difunctionalization of alkenes and the mechanistic scenarios governing the stereocontrol, with an emphasis on utilization of chiral ligands.

Links between size fractionation, chemical speciation of dissolved copper and chemical speciation of dissolved organic matter in the Loire estuary

Environmental contextThe toxicity of copper to aquatic life is highly dependent on its chemical form. In the vineyards of the Loire valley, mixtures of copper compounds are increasingly being used as fungicides. Our study investigating the origin and behaviour of dissolved copper on the land-sea continuum of the Loire advances our understanding of the chemical forms and fate of copper in estuarine systems. AbstractWe present data on the organic speciation of dissolved copper (dCu) in the Loire estuary for the soluble (<0.02µm) and dissolved (<0.45µm) fractions. These results were interpreted according to the distribution of natural organic matter along the estuary. We observed a high concentration of dCu (80nmolkg−1) upstream of the tidal front (S=0.1, where S is the salinity), possibly induced by drainage from vineyards located on the watershed of the estuary, and a concentration typical of coastal seawater at the end of the salinity gradient (3–4nmolkg−1). dCu showed a non-conservative distribution along the estuary with a notably strong decrease in concentration at the very first stage of mixing (S ~ 0.5) that increased again at low salinity (S=4.7). The latter increase in the concentration of dCu was related to the supply of colloidal copper induced by particle desorption in the maximum turbidity zone. The organic speciation of dCu revealed that the complexing capacity of copper ligands (LCu, up to 147 nanomoles of Cu per kilogram of water) exceeded dCu in both the soluble and dissolved fractions, which kept the activity of cupric ions below toxic levels for most unicellular phytoplankton. Humic substances comprised up to 95% of LCu in the continental shelf sample, but their complexing capacity did not account for all of the LCu in the inner estuary. We conducted pseudopolarographic experiments and found two other additional ligand classes: thiol-like and amino-acids/proteins. While humic substances are the dominant component of dissolved organic matter (DOM), the study of DOM suggested the release of colloidal DOM from a wastewater treatment plant. This structure could be a major source of proteinaceous LCu in the system that changes the dCu speciation in the middle of the estuary.

Computational Design of Copper Ligands with Controlled Metal Chelating, Pharmacokinetics, and Redox Properties for Alzheimer’s Disease

Background: Redox active metal cations, such as Cu2 +, have been related to induce amyloid plaques formation and oxidative stress, which are two of the key events in the development of Alzheimer’s disease (AD) and others metal promoted neurodegenerative diseases. In these oxidative events, standard reduction potential (SRP) is an important property especially relevant in the reactive oxygen species formation. Objective: The SRP is not usually considered for the selection of drug candidates in anti-AD treatments. In this work, we present a computational protocol for the selection of multifunctional ligands with suitable metal chelating, pharmacokinetics, and redox properties. Methods: The filtering process is based on quantum chemical calculations and the use of in silico tools. Calculations of SRP were performed by using the M06-2X density functional and the isodesmic approach. Then, a virtual screening technique (VS) was used for similar structure search. Results: Protocol application allowed the assessment of chelating, drug likeness, and redox properties of copper ligands. Those molecules showing the best features were selected as molecular scaffolds for a VS procedure in order to obtain related compounds. After applying this process, we present a list of candidates with suitable properties to prevent the redox reactions mediated by copper(II) ion. Conclusion: The protocol incorporates SRP in the filtering stage and can be effectively used to obtain a set of potential drug candidates for AD treatments.

Synthesis and efficacy of copper(II) complexes bearing N(4)-substituted thiosemicarbazide and diimine co-ligands on plasmid DNA and HeLa cell lines

This present work deals with the synthesizes of nine novel thiosemicarbazone copper(II) complexes {[Cu(L)2]Cl C3, [Cu(L)(bpy)]Cl C4?C6, [Cu(L) (phen)]Cl C7?C9 (where, L = H(L1)?H(L3), H(L1) = (E)-N-methyl-2- -(1-phenyl-2-((5-(pyridin-3-yl)-4H-1,2,4-triazol-3-yl)thio)ethylidene)hydrazinecarbothioamide, H(L2) = (E)-N-ethyl-2-(1-phenyl-2-((5-(pyridin-3-yl)-4H- -1,2,4-triazol-3-yl)thio)ethylidene) hydrazinecarbothioamide, H(L3) = (E)-N- -phenyl-2-(1-phenyl-2-((5-(pyridin-3-yl)-4H-1,2,4-triazol-3-yl)thio)ethylidene) hydrazinecarbothioamide, bpy = 2,2?-bipyridyl and phen = 1,10-phenanthroline) with improved pharmacological results. The synthesized complexes were characterized by various spectral-analytical techniques. The structure of the copper(II) complexes C1?C9 was proposed by EPR spectroscopy. It confirmed the square planar coordination around Cu(II) complexes. The antibacterial screening of the complexes revealed that complexes C7 and C8 demonstrated significant activity against Gram-positive (B. thuringiensis) and Gram-negative (E. coli) bacteria. The concentration-dependent DNA cleavage activity of supercoiled (SC) pUC18 DNA exhibited complete DNA degradation effect on complex C6 at a minimum concentration of 40 ?M. In vitro cytotoxic results showed that the mixed ligand copper(II) complexes C4, C5 and C7 exhibited higher effects on human cervical cancer cell lines, HeLa, when compared to cisplatin. Hence, the results obtained from each biological screening indicated the superior biological efficacy of the mixed ligand copper(II) complexes bearing diimine moieties. It could be considered as a promising alternative to an existing anticancer drug.

In‐silico and In‐vitro Studies on the DNA/BSA‐Binding Features of a Mixed Ligand Copper (II) Complex Containing 2‐Methyl Imidazole and a Schiff Base Ligand

AbstractThe study aimed at investigating the binding features of the mixed ligand Copper (II) complex to BSA and DNA. Both in‐silico and in‐vitro analyses were made to fully assess the binding mechanism and mode of the Copper (II) complex to BSA and DNA. Spectroscopic tests demonstrated the Copper (II) complex reacted with DNA through binding to its minor grooves with the association constant 3.36×103 M−1. This type of interaction was confirmed by molecular docking simulations. Tryptophan quenching analyses at 298, 303 and 308 K showed that the Copper (II) complex reacted with the BSA's ground‐state fluorophore and created a non‐fluorescent adduct. In other words, a static quenching approach was offered with the quenching rate constants within the span of 3.4×1012‐1.28×1013 M−1s−1. Besides, the values of binding constants at various temperatures were achieved, implying the moderate similarity of the Copper (II) complex to the serum's albumin. Research on thermodynamic factors suggested the complex‐BSA bond was an enthalpy‐induced reaction where Van der Waals forces and the hydrogen bond performed the leading role. The simulations of molecular docking verified the test results and demonstrated the amino acids engaged in the bond between BSA and the Copper (II) complex.

Experimental and theoretical substantiation of differences of geometric isomers of copper(II) α-amino acid chelates in ATR-FTIR spectra.

Stereo and structural isomerism of the copper(II) chelate complexes define their biological activity. At the same time, the identification of the geometric isomers of such complexes is a nontrivial task of modern coordination chemistry. In the presented work we have studied the trans- and cis-isomers of chelates bis(S-valinato)copper(II), (R,S-valinato)copper(II) and other mixed ligand copper(II) amino acid complexes with the joint use of experimental by ATR-FTIR spectroscopy and DFT simulations. Using DFT simulations (method M06/6 311+G(d)) the optimum conformers of the geometric isomers of copper(II) a-amino acid chelate complexes were found and their characteristic stretching vibrations were established in the mid-wave region of the IR spectra. The experimental ATR-FTIR bands of the compounds well agree with the theoretical estimates. Such a joint use allows to determine of cis- and trans-isomers of copper(II) N,O-amino acid chelates in the mid-wave region of the ATR-FTIR spectrum.

New thiosemicarbazone Schiff base ligands: Synthesis, characterization, catecholase study and hemolytic activity

Two novel thiosemicarbazones ligands have been synthesized and characterized by FT-IR, ESI-MS, 1H NMR, and also by single-crystal X-ray diffraction for L1. The crystal structure shows that L1 molecules are planar and are connected via N-H----S and O-H----S interactions. The catecholase activity of is situ copper and cobalt complexes of this ligands has been investigated against 3,5-di-tert-butylcatechol. The progress of the oxidation reactions was closely monitored over time following the strong peak of 3,5-DTBC using UV–Vis. Oxidation rates were determined from the initial slope of absorbance vs. time plots, then analyzed by Michaelis-Menten equations. Catechol oxidation reactions were realized using different concentrations of copper and cobalt acetate and ligands (L/Cu: 1/1, 1/2, 2/1). The results show that all complexes were able to catalyze the oxidation of 3,5-DTBC. Acetate complexes have the highest activity. CuL1 and CoL1 complexes act as a catalyst and inhibitor. While copper and cobalt complexes obtained from ligand L2 illustrate concentration-independent oxidation activation. The hemolysis study performed by L1 increases as a function of its concentration. However, ligand L2 has no hemolytic effect.

Copper-binding energetics of amicyanin in different folding states.

Amicyanin is a type I copper protein that mediates electron transfer between methylamine dehydrogenase and cytochrome c-551i for energy production in Paracoccus denitrificans. Although the Met98 axial ligand of amicyanin has been shown to dictate metal selectivity and specificity during protein folding, the mechanism involved in copper-mediated amicyanin folding is unknown. Here, we kinetically and spectroscopically described reaction steps for incorporating copper into fully and less folded apo-amicyanin and established thermodynamic parameters for two amicyanin folding states. The rate constant for the incorporation of copper into fully folded apo-amicyanin at 25 °C was almost 1.5-fold lower than that for the initial phase of copper addition to the less folded apo-amicyanin. However, the rate constant was 10-fold higher than that of the second phase of copper addition to less folded apo-amicyanin at 25 °C. When overall binding energetic parameters (ΔH° and ΔS°) for the incorporation of copper into fully folded apo-amicyanin were measured by the van't Hoff method and isothermal titration calorimetry, the values were more positive than those determined for less folded apo-amicyanin. This indicates that during amicyanin biogenesis, copper rapidly binds to an unfolded apo-amicyanin active site, inducing protein folding and favorably influencing subsequent organization of copper ligands.

Aromatic versus Aliphatic α-Diimine Ligands in Heteroleptic Copper(I) Emitters: Photophysical and Electrochemical Properties.

The electrochemical and photophysical properties of a heteroleptic Cu(I) complex bearing an aliphatic α-diimine ligand, [Cu(dab)(xantphos)]+ (Cu-dab; dab = N,N'-diphenyl-2,3-dimethyl-1,4-diazabutadiene, xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene), were evaluated together with those of complexes [Cu(dmp)(xantphos)]+ (Cu-dmp; dmp = 2,9-dimethyl-1,10-phenanthroline), [Cu(dmbpy)(xantphos)]+ (Cu-dmbpy; dmbpy = 5,5'-dimethyl-2,2'-bipyridine), and [Cu(bq)(xantphos)]+ (Cu-bq; bq = 2,2'-biquinoline), bearing aromatic diimine ligands. Cu-dab exhibited a two-step ligand-centered redox behavior, where the first wave corresponded to an electrochemically reversible one-electron reduction process. Although Cu(I)-aromatic diimine complexes Cu-dmp, Cu-dmbpy, and Cu-bq exhibited obvious luminescence from the metal-to-ligand charge transfer (MLCT) excited state, Cu-dab did not show any luminescence. Computational studies indicated that this non-luminescent property was caused by the large structural relaxation of Cu-dab during photoexcitation.

Solvatochromism of Copper(II) Complexes Derived from Trifluoroacetylacetone and Dinitrogen Ligands

Mixed ligand copper(II) complexes of the empirical formula [Cu (L)(TFAA)]X, where L represents 2,2´-bipyridine (Bipy), 1,10´-phenanthroline (Phen), or 4,7-diphenyl-1,10´- phenanthroline (Dphen), TFAA is 1,1,1-Trifluoro-2,4-pentanedione, and X is the counter ion (BF4- or ClO4-), were synthesized and characterized by spectroscopic, magnetic, molar conductance, elemental, and thermal analysis. Solvatochromic studies revealed that all the complexes showed bathochromic shifts. A square planar geometric structure is proposed for the perchlorate and tetrafluoroborate complexes. Spectral properties supported a square planar structure provided by the N2O2 chromophores. The mixed ligand copper complexes exhibited promising catalytic activity in the decomposition of hydrogen peroxide via the first-order reaction; the catalytic efficiency of perchlorate complexes was greater than that of tetrafluoroborate complexes. Potentiometric analyses of the aqueous mixed ligand copper complexes were carried out. The protonation constants of the free ligands and the stability constants of the complexes were determined using pH titration. The sequence of the stability of ternary complexes with respect to their ligands decreased in the order: Bipy˃ Phen˃ Dphen. The kinetic and thermodynamic parameters were calculated using the Coat-Redfern equation. The stability of the complexes was observed to be in line with the results obtained from the potentiometric analyses. The synthesized complexes were examined for their antimicrobial activity against two pathogenic bacteria (Staphylococcus aureus)as Gram-positive bacteria and (Pseudomonas fluorescens) as Gram-negative bacteria and one type of fungus (Fusarium oxysporum). The results indicated that the complexes exhibited higher antimicrobial activity than the ligands. It was also observed that perchlorate complexes had higher activity than tetrafluoroborate, and the growth of inhibitory activity of the complexes followed the order Bipy˃ Phen˃ Dphen.

ROS-mediated cell death induced by mixed ligand copper(II) complexes of l-proline and diimine: effect of co-ligand

A series of mixed-ligand Cu(II) complexes of the type: (i) [Cu(l-pro)(diimine)(H2O)n](ClO4) (n = 0 or 1), where l-pro is l-proline and diimine is 2,2′-bipyridine (bpy; 1), (ii) 4,4′-dimethyl-2,2′-bipyridine (dmbpy; 2), (iii) 1,10-phenanthroline (phen; 3), (iv) 5,6-dimethyl-1,10-phenanthroline (5,6-dmp; 4), (v) 3,4,7,8-tetramethyl-1,10-phenanthroline (3,4,7,8-tmp; 5), (vi) dipyrido-[3,2-f:2′,3′-h]-quinoxaline (dpq; 6), and (vii) dipyrido[3,2-a:2′,3′-c]phenazine (dppz; 7) have been synthesized and characterized systematically. Complexes 2 and 3 have been structurally characterized. DNA- and protein-binding and cleavage studies revealed that 7 possesses stronger DNA- and protein-binding efficiency and also exhibits self-activating DNA-cleavage in the absence of an activating agent. The hydrophobic complexes 4 and 5 induced self-activated protein cleavage and yielded a single-cleaved fragment each. The cytotoxic property of all the seven complexes was examined by incubation with the human small cell lung carcinoma cell line A549. Complexes 4 and 6 exhibited almost similar cytotoxic properties [IC50 = 1.4 µM (4) and 1.3 µM (6)], which was 9.3 and 10 times, respectively, more efficient than cisplatin (IC50 = 13 µM). Complex 4 induced generation of the highest level of intracellular ROS which correlates with its efficient cytotoxic activity and provides scope for further investigation as a potential anticancer agent.

Synthesis, characterization, spectroscopic and electrochemical investigation of 2-aminopyridine-3-carboxylic acid copper(II) complexes with diimine

ABSTRACT Three mixed- ligand copper(II)-organic coordination compounds were synthesized by using 2-aminopyridine-3-carboxylic acid (2-APCA) as a primary ligand while the aromatic diimines, viz., 2,2′-bipyridine (2,2′-bipy), 1,10-phenanthroline (1,10-phen) and 2,9-dimethyl-1,10-phenanthroline (dmp) as secondary ligands in aqueous/ nonaqueous media. These complexes are formulated as: [Cu(2-APCA)(bipy)(ONO2)] 1; [Cu(2-APCA)(phen)(H2O)](NO3) 2, and [Cu(2-APCA)2(dmp)(H2O)](NO3) 3. All these complexes (1–3) have been characterized by elemental analysis, molar conductance measurements, FT-IR, UV–Visible spectroscopic technique, room temperature magnetic susceptibility measurements, TGA and DSC of these complexes also done. Molar conductance measurements have been carried out in DMSO and DMF, complexes 1 and 3 correspond to non-electrolyte and complex 2 represents monocationic nature. The redox properties of the all these complexes were extensively investigated by electrochemical method using cyclic voltammetry (CV). The electrochemical behavior of complex 3, involving dmp as the secondary ligand is different from rest of two mixed-ligand Cu(II) complexes. Based on these studies, a square-pyramidal coordination geometry around the Cu(II) ion has been proposed in solid complexes (1–3). In DMSO and DMF solutions, complexes 1, 2 and 3 possess distorted octahedral geometry due to solvent coordination.

Erratum to: Synthesis and Structural Characterization of a Monomeric Mixed Ligand Copper(II) Complex Involving N,N,N′,N′-Tetramethylethylenediamine and Mefenamate

Erratum to: Synthesis and Structural Characterization of a Monomeric Mixed Ligand Copper(II) Complex Involving N,N,N′,N′-Tetramethylethylenediamine and Mefenamate

Synthesis, spectral, electrochemical, in-vitro antimicrobial and antioxidant activities of bisphenolic mannich base and 8-hydroxyquinoline based mixed ligands and their transition metal complexes

A new series of cobalt(II), nickel(II), copper(II) and zinc(II) mixed ligand complexes, based on bisphenolic Mannich base, 2,2’-(((2-(dimethylamino)ethyl)azanediyl)bis(methylene))bis(4-(tert-butyl)phenol) and 8-hydroxyquinoline (Q) was prepared and characterized by spectroscopic techniques, magnetic study, molar conductivity and cyclic voltammetry. Spectral and magnetic data measurements are described as octahedral geometry for all the complexes. The redox behavior of metal complexes was investigated by cyclic voltammetry. All the compounds were screened for anti-bacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococci species and anti-fungal activity against Aspergillus niger, Penicillium species by the disk-agar diffusion method. All the compounds have shown better potency against the tested bacteria and fungi. Moreover, they have shown significant antioxidant capacity on the basis of an antioxidant assay.

Halide bridged novel ternary copper(I) complexes with bis imino-quinolinyl ligand and triphenylphosphine: Synthesis, structure, luminescence, electrochemistry and theoretical studies

Three new mixed ligand copper(I) halide complexes [Cu2(µL)(µ-I)2(PPh3)2]∞(1), [Cu2(µ-L) (µ-Br)2(PPh3)2]∞ (2) and [Cu2(µL)(µ-Cl)2)(PPh3)2]∞ (3) have been synthesized by exploiting reactions of equimolar proportion of CuX (X = I, Br and Cl), PPh3 and the imino-quinolinyl ligand L[N,N’-bis(4-quinoline)ideneethylenediamine]. These complexes have been characterized by elemental analyses, IR, UV–Vis and emission spectroscopy. The crystal structures of the complexes 1, 2 and 3 have been determined by single-crystal X-ray analysis and it has been found that all the complexes 1, 2 and 3 are 1-D co-ordination polymer having bridged ligand L and -{CuI-(µ-X2)-CuI}- rhomboid core (X = I, Br and Cl). At room temperature in dichloromethane the ligand L is non-emissive whereas the complexes 1, 2 and 3 are photo luminescent. The E1/2 values of the CuI-CuII couples of 1, 2 and 3 are 0.99, 1.02 and 0.96 V (vs. Ag/AgCl in 1 M KCl, scan rate 100 mV s−1) respectively. From TGA analysis it has been confirmed that these complexes are stable upto 260 °C. DFT and Hirshfeld surfaces computational studies have also been performed for these ternary complexes 1, 2 and 3.

Mild temperature amination of aryl iodides and aryl bromides with aqueous ammonia in the presence of CuBr and pyridyldiketone ligands

Catalytic systems based on copper and simple ligands of ambidentate pyridyldiketone type were used in direct amination of aryl iodides and bromides with aqueous ammonia in one of the mildest conditions described in the literature, with reaction temperature ranging between 25 and 80 °C.

Experimental and computational characterization of structural and spectroscopic features of mixed ligand copper complexes-prototypes for square-pyramidal stereochemistry

Two new mixed ligand copper complexes with 1,10-phenanthroline and monodentate pyrazoles (3,5-dimethyl-4-R-pyrazole, where R = nitro or iodo), stand as case-studies for a revisited view on Ligand-Field (LF) qualitative and semi-quantitative issues, brought in conjunction with the rich information offered by the state-of-the art computational methods. The combined analysis of the first TD-DFT energies and density difference maps enables a scheme of the LF split in the complexes with a specific variety of square-pyramidal coordination geometry, namely the case when the π-type anisotropy due to the two types of aromatic amine ligands shows different orientation with respect of the averaged basal plane. The density difference maps were used as ancillary tools for checking the coordination process and observing the nephelauxetic effect. Clear correlations are drawn between computed and experimental UV–Vis and EPR spectra, rationalizing the Landé factors in terms of Ligand Field states.

Synthesis and Structural Characterization of a Monomeric Mixed Ligand Copper(II) Complex Involving N,N,N′,N′-Tetramethylethylenediamine and Mefenamate

A monomeric ternary complex [Cu(tmen)(mef)2] (1) (where mef = mefenamate anion (C15H15NO21−, tmen = N,N,N′,N′-tetramethylethylenediamine) is prepared by the reaction of CuCl2·2H2O, mefenamic acid (mefH = 2-(2,3-dimethylphenyl)aminobenzoic acid), and N,N,N′,N′-tetramethylethylenediamine (tmen) in the presence of sodium hydroxide. Complex 1 is characterized by the elemental combustion analysis, UV-visible and FT–IR spectroscopy, thermal analysis, and single crystal X-ray diffraction. From the crystal structure of complex 1, it is evident that each copper(II) ion is six-coordinate and is bonded to chelating tmen, and four O atoms of two mef anions (mef1–). In the crystal, the intramolecular hydrogen bonding exists between the H atom of the –NH group of mef and the O atom of one of the coordinated carboxylate O atoms, belonging to the same mef ligand. Complex 1 is tested for antibacterial properties against four strains, including Staphylococcus aureus, Bacillus spizizenii, Escherichia coli, and Klebsiella pneumonia. The complex shows a biological activity against Staphylococcus aureus and Bacillus spizizenii.

Distribution of copper-complexing ligands in Canadian Arctic waters as determined by immobilized copper(II)-ion affinity chromatography

Complexation by dissolved organic ligands affects the bioavailability and distribution of copper and other bioactive trace metals in seawater. However, relatively little is known about the origin and identity of marine copper-complexing ligands, particularly in Arctic waters. We used immobilized copper(II)-ion affinity chromatography (IMAC) to isolate dissolved (< 0.2 μm) copper ligands from seawater samples collected during the 2015 Canadian Arctic GEOTRACES expedition. UV detection at 254 nm was employed to monitor elution of the compounds retained by IMAC. The areas of the resulting peaks were used to generate depth profiles that show, for the first time, how copper ligands are distributed across the Canadian Arctic. Copper ligand concentrations ranged from 0.9 to 4.8 nM, the depth of highest ligand concentration often coinciding with the chlorophyll maximum depth. Correlations between ligand concentration and in situ chlorophyll-a fluorescence suggest that marine phytoplankton or cyanobacteria could be an important source of copper ligands. A correlation was also observed between copper ligand and dissolved copper concentrations in Baffin Bay. Comparison of these results with published data for humic substances and other dissolved organic matter suggests that terrestrial input contributes to the pool of ligands captured by IMAC, particularly in the Canada Basin and Canadian Arctic Archipelago.