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Walker AN, Ayala MA, Mondal S, Bergagnini MC, Bui PJD, Chidester SN, Doeden CI, Esjornson L, Sweany BR, Garcia L, Krause JA, Oliver AG, Prior TJ, Hubin TJ. A Bridge too Far? Comparison of Transition Metal Complexes of Dibenzyltetraazamacrocycles with and without Ethylene Cross-Bridges: X-ray Crystal Structures, Kinetic Stability, and Electronic Properties. Molecules 2023; 28:895. [PMID: 36677952 PMCID: PMC9863842 DOI: 10.3390/molecules28020895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/18/2023] Open
Abstract
Tetraazamacrocycles, cyclic molecules with four nitrogen atoms, have long been known to produce highly stable transition metal complexes. Cross-bridging such molecules with two-carbon chains has been shown to enhance the stability of these complexes even further. This provides enough stability to use the resulting compounds in applications as diverse and demanding as aqueous, green oxidation catalysis all the way to drug molecules injected into humans. Although the stability of these compounds is believed to result from the increased rigidity and topological complexity imparted by the cross-bridge, there is insufficient experimental data to exclude other causes. In this study, standard organic and inorganic synthetic methods were used to produce unbridged dibenzyl tetraazamacrocycle complexes of Co, Ni, Cu, and Zn that are analogues of known cross-bridged tetraazamacrocycles and their transition metal complexes to allow direct comparison of molecules that are identical except for the cross-bridge. The syntheses of the known tetraazamacrocycles and the new transition metal complexes were successful with high yields and purity. Initial chemical characterization of the complexes was conducted by UV-Visible spectroscopy, while cyclic voltammetry showed more marked differences in electronic properties from bridged versions. Direct comparison studies of the unbridged and bridged compounds' kinetic stabilities, as demonstrated by decomposition using high acid concentration and elevated temperature, showed that the cyclen-based complex stability did not benefit from cross-bridging. This is likely due to poor complementarity with the Cu2+ ion while cyclam-based complexes benefited greatly. We conclude that ligand-metal complementarity must be maintained in order for the topological and rigidity constraints imparted by the cross-bridge to contribute significantly to complex robustness.
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Affiliation(s)
- Ashlie N. Walker
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Megan A. Ayala
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Somrita Mondal
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Mackenzie C. Bergagnini
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Phuong John D. Bui
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Stephanie N. Chidester
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Chad I. Doeden
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Louise Esjornson
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Brian R. Sweany
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Leslie Garcia
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
| | - Jeanette A. Krause
- Department of Chemistry, University of Cincinnati, Cincinnati, OH 45220, USA
| | - Allen G. Oliver
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Timothy J. Prior
- Department of Chemistry, School of Natural Sciences, University of Hull, Kingston Upon Hull HU6 7RX, UK
| | - Timothy J. Hubin
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK 73096, USA
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Synthesis and Characterization of Late Transition Metal Complexes of Mono-Acetate Pendant Armed Ethylene Cross-Bridged Tetraazamacrocycles with Promise as Oxidation Catalysts for Dye Bleaching. MOLECULES (BASEL, SWITZERLAND) 2022; 28:molecules28010232. [PMID: 36615426 PMCID: PMC9822179 DOI: 10.3390/molecules28010232] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 12/03/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022]
Abstract
Ethylene cross-bridged tetraazamacrocycles are known to produce kinetically stable transition metal complexes that can act as robust oxidation catalysts under harsh aqueous conditions. We have synthesized ligand analogs with single acetate pendant arms that act as pentadentate ligands to Mn, Fe, Co, Ni, Cu, and Zn. These complexes have been synthesized and characterized, including the structural characterization of four Co and Cu complexes. Cyclic voltammetry demonstrates that multiple oxidation states are stabilized by these rigid, bicyclic ligands. Yet, redox potentials of the metal complexes are modified compared to the "parent" ligands due to the pendant acetate arm. Similarly, gains in kinetic stability under harsh acidic conditions, compared to parent complexes without the pendant acetate arm, were demonstrated by a half-life seven times longer for the cyclam copper complex. Due to the reversible, high oxidation states available for the Mn and Fe complexes, the Mn and Fe complexes were examined as catalysts for the bleaching of three commonly used pollutant model dyes (methylene blue, methyl orange, and Rhodamine B) in water with hydrogen peroxide as oxidant. The efficient bleaching of these dyes was observed.
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Johnston HM, Freire DM, Mantsorov C, Jamison N, Green KN. Manganese (III/IV) μ-Oxo Dimers and Manganese (III) Monomers with Tetraaza Macrocyclic Ligands and Historically Relevant Open-Chain Ligands. Eur J Inorg Chem 2022; 2022:e202200039. [PMID: 36277657 PMCID: PMC9585891 DOI: 10.1002/ejic.202200039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Indexed: 11/11/2022]
Abstract
The oxygen-evolving complex (OEC) located in photosystem II (PSII) of green plants is one of the best-known examples of a manganese-containing enzyme in nature, but it is also used in a range of other biological processes. OEC models incorporate two multi-dentate nitrogen-containing ligands coordinated to a bis-μ-oxo Mn(III,IV) core. Open-chain ligands were the initial scaffold used for biomimetic studies, but their macrocyclic counterparts have proven to be particularly appropriate due to their enhanced stability. Dimer and monomer complexes with such ligands have shown to be useful for a wide range of applications, which will be reviewed herein. The purpose of this review is to state with some clarity the different spectroscopic and structural characteristics of the Mn complexes formed with tetraaza macrocyclic ligands both in solution and solid-state that allow the reader to successfully identified the species involved when dealing with similar complexes of Mn.
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Affiliation(s)
- Hannah M Johnston
- Texas Christian University, Department of Chemistry and Biochemistry,2950 W. Bowie, Fort Worth, TX 76129, USA
| | - David M Freire
- Texas Christian University, Department of Chemistry and Biochemistry,2950 W. Bowie, Fort Worth, TX 76129, USA
| | - Christina Mantsorov
- Texas Christian University, Department of Chemistry and Biochemistry,2950 W. Bowie, Fort Worth, TX 76129, USA
| | - Nena Jamison
- Texas Christian University, Department of Chemistry and Biochemistry,2950 W. Bowie, Fort Worth, TX 76129, USA
| | - Kayla N Green
- Texas Christian University, Department of Chemistry and Biochemistry,2950 W. Bowie, Fort Worth, TX 76129, USA
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Reiersølmoen AC, Solvi TN, Fiksdahl A. Au(III) complexes with tetradentate-cyclam-based ligands. Beilstein J Org Chem 2021; 17:186-192. [PMID: 33564328 PMCID: PMC7849238 DOI: 10.3762/bjoc.17.18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/23/2020] [Indexed: 12/26/2022] Open
Abstract
Chiral cyclam (1,4,8,11-tetraazacyclotetradecane) derivatives were synthesized stepwise from chiral mono-Boc-1,2-diamines and (dialkyl)malonyl dichloride via open diamide-bis(N-Boc-amino) intermediates (65-91%). Deprotection and ring closure with a second malonyl unit afforded the cyclam tetraamide precursors (80-95%). The new protocol allowed the preparation of the target cyclam derivatives (53-59%) by a final optimized hydride reduction. Both the open tetraamine intermediates and the cyclam derivatives successfully coordinated with AuCl3 to give moderate to excellent yields (50-96%) of the corresponding novel tetra-coordinated N,N,N,N-Au(III) complexes with alternating five- and six-membered chelate rings. The testing of the catalytic ability of the cyclam-based N,N,N,N-Au(III) complexes demonstrated high catalytic activity of some complexes in selected test reactions (full conversion in 1-24 h, 62-97% product yields).
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Affiliation(s)
- Ann Christin Reiersølmoen
- Department of Chemistry, Norwegian University of Science and Technology, Høgskoleringen 5, 7491, Trondheim, Norway
| | - Thomas N Solvi
- Department of Chemistry, Norwegian University of Science and Technology, Høgskoleringen 5, 7491, Trondheim, Norway
| | - Anne Fiksdahl
- Department of Chemistry, Norwegian University of Science and Technology, Høgskoleringen 5, 7491, Trondheim, Norway
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DFT studies on the structure and stability of tetraaza macrocyclic nickel(II) complexes containing dicarbinolamine ligand moiety. J CHEM SCI 2019. [DOI: 10.1007/s12039-019-1688-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Le Bihan T, Le Bris N, Bernard H, Platas-Iglesias C, Tripier R. Synthesis of Orthogonal N
-Protected C
-Functional Side-Bridged Cyclams to Give Access to Unsymmetrical Constrained BCAs. European J Org Chem 2019. [DOI: 10.1002/ejoc.201901013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Thomas Le Bihan
- UMR CNRS-UBO 6521 CEMCA; Univ Brest; 6 avenue Victor le Gorgeu 29200 Brest France
| | - Nathalie Le Bris
- UMR CNRS-UBO 6521 CEMCA; Univ Brest; 6 avenue Victor le Gorgeu 29200 Brest France
| | - Hélène Bernard
- UMR CNRS-UBO 6521 CEMCA; Univ Brest; 6 avenue Victor le Gorgeu 29200 Brest France
| | - Carlos Platas-Iglesias
- Departamento de Química; Facultade de Ciencias & Centro de Investigaciones Científicas Avanzadas; Universidade da Coruña; 15071 A Coruña Spain
| | - Raphaël Tripier
- UMR CNRS-UBO 6521 CEMCA; Univ Brest; 6 avenue Victor le Gorgeu 29200 Brest France
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New macrocyclic Cu(II) complex with bridge terephthalate: Synthesis, spectral properties, in vitro cytotoxic and antimicrobial activity. Comparison with related complexes. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2018.10.027] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Cain AN, Carder Freeman TN, Roewe KD, Cockriel DL, Hasley TR, Maples RD, Allbritton EMA, D'Huys T, van Loy T, Burke BP, Prior TJ, Schols D, Archibald SJ, Hubin TJ. Acetate as a model for aspartate-based CXCR4 chemokine receptor binding of cobalt and nickel complexes of cross-bridged tetraazamacrocycles. Dalton Trans 2019; 48:2785-2801. [PMID: 30729243 DOI: 10.1039/c8dt04728f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A number of disease states including WHIM syndrome, HIV infection and cancer have been linked to the chemokine receptor CXCR4. High-affinity CXCR4 antagonist transition metal complexes of configurationally restricted bis-tetraazamacrocyclic ligands have been identified in previous studies. Recently synthesised and structurally characterised Co2+/Co3+ and Ni2+ acetate complexes of mono-macrocycle cross-bridged ligands have been used to mimic their known coordination interaction with the aspartate side chains on binding to CXCR4. Here, X-ray crystal structures for three Co2+/Co3+ acetate complexes and five Ni2+ acetate complexes are presented and demonstrate flexibility in the mode of binding to the acetate ligand concomitantly with the requisite cis-V-configured cross-bridged tetraazamacrocyle. Complexes of the smaller Co3+ metal ion exclusively bind acetate by chelating both oxygens of acetate. Larger Co2+ and Ni2+ metal ions in cross-bridged tetraazamacrocycles show a clear tendency to coordinate acetate in a monodentate fashion with a coordinated water molecule completing the octahedral coordination sphere. However, in unbridged tetraazamacrocycle acetate structures reported in the literature, the coordination preference is to chelate both acetate oxygens. We conclude that the short ethylene cross-bridge restricts the equatorial bulk of the macrocycle, prompting the metal ion to fill the equator with the larger monodentate acetate plus water ligand set. In unbridged ligand examples, the flexible macrocycle expands equatorially and generally only allows chelation of the sterically smaller acetate alone. These results provide insight for generation of optimised bis-macrocyclic CXCR4 antagonists utilising cobalt and nickel ions.
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Affiliation(s)
- Amy N Cain
- Department of Chemistry and Physics, Southwestern Oklahoma State University, Weatherford, OK, USA 73096.
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Ong YC, Roy S, Andrews PC, Gasser G. Metal Compounds against Neglected Tropical Diseases. Chem Rev 2018; 119:730-796. [DOI: 10.1021/acs.chemrev.8b00338] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Yih Ching Ong
- Laboratory for Inorganic Chemical Biology, Chimie ParisTech, PSL University, 11 rue Pierre et Marie Curie, F-75005 Paris, France
| | - Saonli Roy
- Department of Chemistry, University of Zurich, Wintherthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Philip C. Andrews
- School of Chemistry, Monash University, Wellington Road, Clayton, Victoria 3800, Australia
| | - Gilles Gasser
- Laboratory for Inorganic Chemical Biology, Chimie ParisTech, PSL University, 11 rue Pierre et Marie Curie, F-75005 Paris, France
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Snider VG, Pella BJ, Mukherjee A. Synthesis, characterization, and reactivity of copper complexes supported by the TPMEN ligand framework. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2017.09.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Park SV, Berry JF. Synthesis, characterization and solution behavior of a systematic series of pentapyridyl-supported Ru II complexes: comparison to bimetallic analogs. Dalton Trans 2017; 46:9118-9125. [PMID: 28664959 PMCID: PMC6774635 DOI: 10.1039/c7dt01847a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of RuII complexes stabilized with the pentapyridyl ligand Py5Me2 (Py5Me2 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine) and with an axial X ligand (X = Cl-, H2O, N3-, MeCN) were prepared and characterized in the solid state and in non-aqueous solution. The cyclic voltammograms of these complexes in MeCN reflect a reversible substitution of the axial X ligand with MeCN. Irreversible ligand substitution of [(Py5Me2)RuN3]+ is also observed in propylene carbonate, but only at oxidizing potentials that decompose the azide ligand. The monometallic chloride and azide species are compared with analogous Ru2 metal-metal bonded complexes, which have been reported to undergo irreversible chloride dissociation upon reduction.
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Affiliation(s)
- Sungho V Park
- Department of Chemistry, University of Wisconsin - Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA.
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Qin GF, Qin QY, Long BF, Wei DP, Xu YH, Bao SJ, Yin XH. Structural versatility and electrochemical properties of four copper(II) complexes based on 1H-indazole-3-carboxylic acid. JOURNAL OF THE IRANIAN CHEMICAL SOCIETY 2017. [DOI: 10.1007/s13738-017-1073-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Wilson KR, Cannon-Smith DJ, Burke BP, Birdsong OC, Archibald SJ, Hubin TJ. Synthesis and structural studies of two pyridine-armed reinforced cyclen chelators and their transition metal complexes. Polyhedron 2016; 114:118-127. [PMID: 27346907 DOI: 10.1016/j.poly.2015.11.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Two novel pyridine pendant-armed macrocycles structurally reinforced by an ethyl bridge, either between adjacent nitrogens (for side-bridged) or non-adjacent nitrogens (for cross-bridged), have been synthesized and complexed with a range of transition metal ions (Co2+, Ni2+, Cu2+ and Zn2+). X-ray crystal structures of selected cross-bridged complexes were obtained which showed the characteristic cis-V configuration with potential labile cis binding sites. The complexes have been characterized by their electronic spectra and magnetic moments, which show the expected high spin divalent metal complex in most cases. Exceptions are the nickel side-bridged complex, which shows a mixture of high-spin and low spin, and the cobalt cross-bridged complex which has oxidized to cobalt(III). Cyclic voltammetry in acetonitrile was carried out to assess the potential future use of these complexes in oxidation catalysis. Selected complexes offer significant catalytic potential enhanced by the addition of the pyridyl arm to a reinforced cyclen backbone.
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Affiliation(s)
- Kevin R Wilson
- Department of Chemistry and Physics, Southwestern Oklahoma State University, 100 Campus Drive, Weatherford, Oklahoma 73096, United States
| | - Desiray J Cannon-Smith
- Department of Chemistry and Physics, Southwestern Oklahoma State University, 100 Campus Drive, Weatherford, Oklahoma 73096, United States
| | - Benjamin P Burke
- Department of Chemistry and Positron Emission Tomography Research Centre, University of Hull, Cottingham Road, Hull, HU6 7RX, UK
| | - Orry C Birdsong
- Department of Chemistry and Physics, Southwestern Oklahoma State University, 100 Campus Drive, Weatherford, Oklahoma 73096, United States
| | - Stephen J Archibald
- Department of Chemistry and Positron Emission Tomography Research Centre, University of Hull, Cottingham Road, Hull, HU6 7RX, UK
| | - Timothy J Hubin
- Department of Chemistry and Physics, Southwestern Oklahoma State University, 100 Campus Drive, Weatherford, Oklahoma 73096, United States
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