Oxalato‐Bridged Dinuclear Copper(II) Complexes of <i>N</i>‐Alkylated Derivatives of 1,4,7‐Triazacyclononane: Synthesis, X‐ray Crystal Structures and Magnetic Properties

Belousoff, Matthew J.; Graham, Bimbil; Moubaraki, Boujemaa; Murray, Keith S.; Spiccia, Leone

doi:10.1002/ejic.200600570

Cited by 17 publications

(4 citation statements)

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“…In this kind of system, special attention has been addressed to coordination architectures that include multiatomic bridging ligands (MABLs). Thus, MABLs such as oxalate − azide − or 2,2′-bipyrimidine (bpym) − have been extensively used in magneto-structural studies because of their remarkable ability in mediating magnetic interactions between paramagnetic centers as well as the variety of dimensionalities (from both structural and magnetic points of view) and topologies that they can originate when adopting different coordination modes. Despite the variety of bpym-including ternary systems characterized, those that include carboxylate groups are relatively uncommon.…”

Section: Introductionmentioning

confidence: 99%

Alternating Ferro/Antiferromagnetic Copper(II) Chain Containing an Unprecedented Triple Formato/Hydroxido/Sulfato Bridge

et al. 2016

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The first example of a triple formato/hydroxido/sulfato (FHS) bridge for any metal is reported in compound [Cu2(bpym)(OH)(HCO2)(SO4)(H2O)2]·3H2O (1). Its structure shows the presence of alternating triple FHS bridges and 2,2'-bipyrimidine (bpym) ones. Although in the initial synthesis the sulfate anions were introduced accidentally, here we report the rational synthesis and the magnetic properties of this compound. The magnetic properties show that 1 is an alternating ferro/antiferromagnetic (F/AF) chain compound with predominant antiferromagnetic interactions and were fit to an alternating F/AF S = (1)/2 chain with g = 2.103, JAF = -139 cm(-1), and JF = 116 cm(-1) (α = JF/|JAF| = 0.83). The JAF value found corresponds very well to those previously reported for Cu-bpym-Cu bridges (average value of ca. -150 cm(-1)). The JF value is also very close to the estimated one (ca. 100 cm(-1)) from magneto-structural correlations in triply Cu-Cu bridged compounds with both hydroxido and carboxylato bridges in equatorial positions.

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Section: Introductionmentioning

confidence: 99%

Alternating Ferro/Antiferromagnetic Copper(II) Chain Containing an Unprecedented Triple Formato/Hydroxido/Sulfato Bridge

et al. 2016

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Section: Structural Models For Metallobiositesmentioning

confidence: 83%

“…Systematic variation of the intramolecular Cu–Cu distance in these binuclear models also showed that the electronic interaction between the Cu II centres diminishes with increasing separation. The complexes studied range from ones that display moderate antiferromagnetic coupling, for example, Cu II 2 – 12 ( J =−86 cm −1 ), which features an endogenous alkoxo‐bridged pair of Cu II centres separated by approximately 3.6 Å, through to complexes exhibiting strong antiferromagnetic interaction between the Cu II centres, for example, Cu II 2 – 13 ( J ≈−150 cm −1 ), which is an oxalato‐bridged binuclear Cu II complex with a large Cu–Cu separation (≈5.2 Å; Figure ). This distance is further reduced (≈3.80 Å) in Cu II 2 – 14 , a cis ‐Cu II 2 (μ‐η 1 :η 1 −O 2 ) complex of pyrazole‐bridged TACN (Figure ), reported by Meyer and co‐workers .…”

Section: Structural Models For Metallobiositesmentioning

confidence: 99%

Harnessing the Coordination Chemistry of 1,4,7‐Triazacyclononane for Biomimicry and Radiopharmaceutical Applications

et al. 2018

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1,4,7‐Triazacyclononane (TACN)‐based mono‐ and poly‐nuclear metal complexes have found extensive use as biological mimics for understanding the structural and operational aspects of complex natural systems. Their coordination flexibility has also provided researchers access to a vast library of radiometal‐binding motifs that display excellent thermodynamic stability and kinetic inertness upon metal complexation. Synthetic modification of the TACN backbone has yielded ligands that can form metal complexes with coordination geometries well suited for these applications. In particular, Leone Spiccia's research has played a significant role in accelerating the progress in these two fields. With a focus on his contributions to the topics of biomimicry and radiopharmaceuticals, this Minireview uses relevant examples to put in perspective the utility of macrocyclic coordination chemistry for biological inorganic chemistry applications.

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“…A major focus of our work has been on new tacn-based ligands capable of generating structural models for copper protein active sites. − The metal centers within copper proteins generally reside in sites generated by four or five metal-coordinating residues, with the coordination sphere completed by aqua ligands and/or substrate donor atoms. For example, histidine residues bind to copper ions in the mono-, di-, or trinuclear Cu(II) sites of hemocyanin, ceruloplasmin, dicopper dismutase, galactose oxidase, catechol oxidase, and quercetin 2,3-dioxygenase .…”

Section: Structural Metallobiosite Modelsmentioning

confidence: 99%

Macrocyclic Metal Complexes for Metalloenzyme Mimicry and Sensor Development

2015

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Examples of proteins that incorporate one or more metal ions within their structure are found within a broad range of classes, including oxidases, oxidoreductases, reductases, proteases, proton transport proteins, electron transfer/transport proteins, storage proteins, lyases, rusticyanins, metallochaperones, sporulation proteins, hydrolases, endopeptidases, luminescent proteins, iron transport proteins, oxygen storage/transport proteins, calcium binding proteins, and monooxygenases. The metal coordination environment therein is often generated from residues inherent to the protein, small exogenous molecules (e.g., aqua ligands) and/or macrocyclic porphyrin units found, for example, in hemoglobin, myoglobin, cytochrome C, cytochrome C oxidase, and vitamin B12. Thus, there continues to be considerable interest in employing macrocyclic metal complexes to construct low-molecular weight models for metallobiosites that mirror essential features of the coordination environment of a bound metal ion without inclusion of the surrounding protein framework. Herein, we review and appraise our research exploring the application of the metal complexes formed by two macrocyclic ligands, 1,4,7-triazacyclononane (tacn) and 1,4,7,10-tetraazacyclododecane (cyclen), and their derivatives in biological inorganic chemistry. Taking advantage of the kinetic inertness and thermodynamic stability of their metal complexes, these macrocyclic scaffolds have been employed in the development of models that aid the understanding of metal ion-binding natural systems, and complexes with potential applications in biomolecule sensing, diagnosis, and therapy. In particular, the focus has been on "coordinatively unsaturated" metal complexes that incorporate a kinetically inert and stable metal-ligand moiety, but which also contain one or more weakly bound ligands, allowing for the reversible binding of guest molecules via the formation and dissociation of coordinate bonds. With regards to mimicking metallobiosites, examples are presented from our work on tacn-based complexes developed as simplified structural models for multimetallic enzyme sites. In particular, structural comparisons are made between multinuclear copper(II) complexes formed by such ligands and multicopper enzymes featuring type-2 and type-3 copper centers, such as ascorbate oxidase (AO) and laccase (Lc). Likewise, with the aid of relevant examples, we highlight the importance of cooperativity between either multiple metal centers or a metal center and a proximal auxiliary unit appended to the macrocyclic ligand in achieving efficient phosphate ester cleavage. Finally, the critical importance of the Zn(II)-imido and Zn(II)-phosphate interactions in Zn-cyclen-based systems for delivering highly sensitive electrochemical and fluorescent chemosensors is also showcased. The Account additionally highlights some of the factors that limit the performance of these synthetic nucleases and the practical application of the biosensors, and then identifies some avenues for the development of more...

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Oxalato‐Bridged Dinuclear Copper(II) Complexes of N‐Alkylated Derivatives of 1,4,7‐Triazacyclononane: Synthesis, X‐ray Crystal Structures and Magnetic Properties

Cited by 17 publications

References 30 publications

Alternating Ferro/Antiferromagnetic Copper(II) Chain Containing an Unprecedented Triple Formato/Hydroxido/Sulfato Bridge

Alternating Ferro/Antiferromagnetic Copper(II) Chain Containing an Unprecedented Triple Formato/Hydroxido/Sulfato Bridge

Harnessing the Coordination Chemistry of 1,4,7‐Triazacyclononane for Biomimicry and Radiopharmaceutical Applications

Macrocyclic Metal Complexes for Metalloenzyme Mimicry and Sensor Development

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