1
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Brink A, Jacobs FJF, Helliwell JR. Trends in coordination of rhenium organometallic complexes in the Protein Data Bank. IUCRJ 2022; 9:180-193. [PMID: 35371500 PMCID: PMC8895017 DOI: 10.1107/s2052252522000665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
Radiopharmaceutical development has similar overall characteristics to any biomedical drug development requiring a compound's stability, aqueous solubility and selectivity to a specific disease site. However, organometallic complexes containing 188/186Re or 99mTc involve a d-block transition-metal radioactive isotope and therefore bring additional factors such as metal oxidation states, isotope purity and half life into play. This topical review is focused on the development of radiopharmaceuticals containing the radioisotopes of rhenium and technetium and, therefore, on the occurrence of these organometallic complexes in protein structures in the Worldwide Protein Data Bank (wwPDB). The purpose of incorporating the group 7 transition metals of rhenium/technetium in the protein and the reasons for study by protein crystallography are described, as certain PDB studies were not aimed at drug development. Technetium is used as a medical diagnostic agent and involves the 99mTc isotope which decays to release gamma radiation, thereby employed for its use in gamma imaging. Due to the periodic relationship among group 7 transition metals, the coordination chemistry of rhenium is similar (but not identical) to that of technetium. The types of reactions the potential model radiopharmaceutical would prefer to partake in, and by extension knowing which proteins and biomolecules the compound would react with in vivo, are needed. Crystallography studies, both small molecule and macromolecular, are a key aspect in understanding chemical coordination. Analyses of bonding modes, coordination to particular residues and crystallization conditions are presented. In our Forward look as a concluding summary of this topical review, the question we ask is: what is the best way for this field to progress?
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Affiliation(s)
- Alice Brink
- Chemistry Department, University of the Free State, Nelson Mandela Drive, Bloemfontein, South Africa
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, United Kingdom
| | - Francois J. F. Jacobs
- Chemistry Department, University of the Free State, Nelson Mandela Drive, Bloemfontein, South Africa
| | - John R. Helliwell
- Department of Chemistry, The University of Manchester, Oxford Road, Manchester, United Kingdom
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2
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Kama DV, Frei A, Brink A, Braband H, Alberto R, Roodt A. New approach for the synthesis of water soluble fac-[M I(CO) 3] + bis(diarylphosphino)alkylamine complexes (M = 99Tc, Re). Dalton Trans 2021; 50:17506-17514. [PMID: 34747429 DOI: 10.1039/d1dt03234h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel proof-of-concept is reported to modify the water solubility and potential biological effects of a bis(diphenylphosphino)alkylamine (PNP) ligand and the corresponding metal complex, by introducing an amine group on the outer periphery of the pendant ligand arm. Thus, a tertiary butoxycarbonyl protected N'-Boc-ethylenediamine-N,N-bis(diphenylphosphino) (N'-Boc-PNP) ligand (1) was synthesized by reacting the protected ethylenediamine and chlorodiphenylphosphine in a 1 : 2 molar ratio. The corresponding fac-[Re(CO)3(N'-Boc-PNP)Br] (1A) complex was then obtained by reacting N'-Boc-PNP (1) with (Et4N)2fac-[Re(CO)3Br3] in equimolar amounts in DCM at 50 °C. De-protection of the N'-Boc pendant amine group in 1A with TFA leads to fac-[Re(NH3+-PNP)(CO)3Br]·CF3COO- (1B) which is soluble in D2O (>0.05 M). Treating 1B with saturated aqueous NaHCO3 yields fac-[Re(NH2-PNP)(CO)3Br]·MeOH (1C) in near quantitative yield. Although both 1A and 1C are not soluble in D2O, addition of TFA easily generates 1B (31P NMR), confirming the formation of the protonated amine. Isolation of fac-[99Tc(CO)3(N-Boc-PNP)(Cl)] (1D) confirmed that the rhenium and technetium (99Tc) can be easily interchanged in this process. Reported are hence the unique rhenium series of compounds 1A, 1B and 1C and the corresponding technetium complex 1D, unequivocally characterized by single crystal XRD, as well as IR and 1H NMR spectroscopy. Preliminary antimicrobial evaluation indicates that ligand 1 and its respective rhenium complexes (1A-1C) were not active against selected fungi (Candida albicans and Cryptococcus neoformans) and bacteria (Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Staphylococcus aureus). These types of ligands and complexes therefore present themselves as excellent radio models for further evaluation using 186Re, 188Re and 99mTc to potentially study the radiotoxicity of appropriately designed complexes.
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Affiliation(s)
- Dumisani V Kama
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein, South Africa, 9300.
| | - Angelo Frei
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
| | - Alice Brink
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein, South Africa, 9300.
| | - Henrik Braband
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
| | - Roger Alberto
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
| | - Andreas Roodt
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein, South Africa, 9300.
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3
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Mishra I, Priyatharsini M, Sathiyendiran M. Synthesis and characterization of binuclear manganese carbonyl complex of 1,4-bis(2-(2′-hydroxyphenyl)benzimidazol-1-yl)benzene and dimethylaminopyridine. J Organomet Chem 2021. [DOI: 10.1016/j.jorganchem.2021.121934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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4
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Kama DV, Frei A, Schutte-Smith M, Brink A, Swart C, Braband H, Alberto R, Roodt A. Exploring preliminary structural relationships and mitochondrial targeting of fac-[MI(CO)3]-bis(diarylphosphino)alkylamine complexes (M = 99Tc, Re). NEW J CHEM 2021. [DOI: 10.1039/d1nj04273d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Preliminary structural relationships in fac-[MI(CO)3]-bis(diarylphosphino)alkylamine complexes (M = 99Tc, Re), antimicrobial and mitochondrial targeting are reported.
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Affiliation(s)
- Dumisani V. Kama
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Angelo Frei
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Marietjie Schutte-Smith
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Alice Brink
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Chantel Swart
- Department of Biochemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Henrik Braband
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Roger Alberto
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Andreas Roodt
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
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5
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Jacobs FJF, Venter GJS, Fourie E, Kroon RE, Brink A. Substitution reactivity and structural variability induced by tryptamine on the biomimetic rhenium tricarbonyl complex. RSC Adv 2021; 11:24443-24455. [PMID: 35479015 PMCID: PMC9036643 DOI: 10.1039/d1ra03750a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/02/2021] [Indexed: 01/28/2023] Open
Abstract
A series of seven fac-[Re(CO)3(5Me-Sal-Trypt)(L)] complexes containing tryptamine on the N,O 5-methyl-salicylidene bidentate ligand backbone and where L is MeOH, Py, Imi, DMAP, PPh3 coordinated to the 6th position have been studied, including the formation of a dinuclear Re2 cluster. The crystallographic solid state structures show marked similarity in structural tendency, in particular the rigidity of the Re core and the hydrogen bond interactions similar to those found in protein structures. The rates of formation and stability of the complexes were evaluated by rapid time-resolved stopped-flow techniques and the methanol substitution reaction indicates the significant activation induced by the use of the N,O salicylidene bidentate ligand as manifested by the second-order rate constants for the entering nucleophiles. Both linear and limiting kinetics were observed and a systematic evaluation of the kinetics is reported clearly indicating an interchange type of intimate mechanism for the methanol substitution. The anticancer activity of compounds 1–7 was tested on HeLa cells and it was found that all compounds showed similar cytotoxicity where solubility allowed. IC50-values between ca. 11 and 22 μM indicate that some cytotoxicity resides most likely on the salicylidene–tryptamine ligand. The photoluminescence of the seven complexes is similar in maximum emission wavelength with little variation despite the broad range of ligands coordinated to the 6th position on the metal centre. The biomimetic tryptamine rhenium tricarbonyl complex shows rapid substitution reactivity on the 6th position as well as cytotoxicity and photoluminescence capability induced by the salicylidene bidentate ligand.![]()
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Affiliation(s)
| | | | - Eleanor Fourie
- Department of Chemistry
- University of the Free State
- Bloemfontein 9300
- South Africa
| | - Robin E. Kroon
- Department of Physics
- University of the Free State
- Bloemfontein 9300
- South Africa
| | - Alice Brink
- Department of Chemistry
- University of the Free State
- Bloemfontein 9300
- South Africa
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6
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Mokolokolo PP, Alexander OT, Schutte-Smith M, Brink A, Roodt A. Crystal structure of monocarbonyl[2-((cyclopentylmethylene)amino)-5-methylphenolato-κ 2N,O] (tricyclohexylphosphine)rhodium(I), C 32H 48NO 2PRh. Z KRIST-NEW CRYST ST 2020. [DOI: 10.1515/ncrs-2020-0248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C32H48NO2PRh, orthorhombic, P212121 (no. 19), a = 26.784(10) Å, b = 8.837(3) Å, c = 12.759(4) Å, V = 3020.0(18) Å3, Z = 4, R
gt(F) = 0.0400, wR
ref(F
2) = 0.0920, T = 100(2) K.
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Affiliation(s)
- Pennie P. Mokolokolo
- Department of Chemistry , University of the Free State , Bloemfontein 9301, South Africa
| | - Orbett T. Alexander
- Department of Chemistry , University of the Free State , Bloemfontein 9301, South Africa
| | | | - Alice Brink
- Department of Chemistry , University of the Free State , Bloemfontein 9301, South Africa
| | - Andreas Roodt
- Department of Chemistry , University of the Free State , Bloemfontein 9301, South Africa
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7
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Kama DV, Brink A, Alberto R, Roodt A. Crystal structure of hexacarbonyl-(μ 2-methanoato-k 2
O: O′)-(μ 2–bis(di- p-tolylphosphino)cyclohexylamine-κ 2
P: P′)dirhenium(I), C 42H 45NO 8P 2Re 2. Z KRIST-NEW CRYST ST 2020. [DOI: 10.1515/ncrs-2019-0632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
C42H45NO8P2Re2, monoclinic, C2/c (no. 15), a = 24.1612(7) Å, b = 13.0229(3) Å, c = 14.9180(4) Å, β = 121.383(3)°, V = 4007.2(2) Å3, Z = 4, R
gt(F) = 0.0235, wR
ref(F
2) = 0.0596, T = 173(2) K.
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Affiliation(s)
- Dumisani V. Kama
- University of the Free State , Chemistry Department , Nelson Mandela Drive , Bloemfontein 9300 , South Africa
| | - Alice Brink
- Department of Chemistry , University of the Free State , P.O. Box 339 , Bloemfontein 9300 , South Africa
| | - Roger Alberto
- Department of Chemistry , University of Zürich , Winterthurerstrasse, 190, 8057 , Zürich , Switzerland
| | - Andreas Roodt
- Department of Chemistry , University of the Free State , P.O. Box 339 , Bloemfontein 9300 , South Africa
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8
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Brink A, Helliwell JR. Why is interoperability between the two fields of chemical crystallography and protein crystallography so difficult? IUCRJ 2019; 6:788-793. [PMID: 31576212 PMCID: PMC6760442 DOI: 10.1107/s2052252519010972] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/06/2019] [Indexed: 05/06/2023]
Abstract
The interoperability of chemical and biological crystallographic data is a key challenge to research and its application to pharmaceutical design. Research attempting to combine data from the two disciplines, small-molecule or chemical crystallography (CX) and macromolecular crystallography (MX), will face unique challenges including variations in terminology, software development, file format and databases which differ significantly from CX to MX. This perspective overview spans the two disciplines and originated from the investigation of protein binding to model radiopharmaceuticals. The opportunities of interlinked research while utilizing the two databases of the CSD (Cambridge Structural Database) and the PDB (Protein Data Bank) will be highlighted. The advantages of software that can handle multiple file formats and the circuitous route to convert organometallic small-molecule structural data for use in protein refinement software will be discussed. In addition some pointers to avoid being shipwrecked will be shared, such as the care which must be taken when interpreting data precision involving small molecules versus proteins.
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Affiliation(s)
- Alice Brink
- Department of Chemistry, University of the Free State, Nelson Mandela Drive, Bloemfontein, Free State 9301, South Africa
- Department of Chemistry, University of Manchester, Brunswick Street, Manchester M13 9PL, UK
| | - John R. Helliwell
- Department of Chemistry, University of Manchester, Brunswick Street, Manchester M13 9PL, UK
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9
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Brink A, Helliwell JR. Formation of a highly dense tetra-rhenium cluster in a protein crystal and its implications in medical imaging. IUCRJ 2019; 6:695-702. [PMID: 31316813 PMCID: PMC6608631 DOI: 10.1107/s2052252519006651] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 05/09/2019] [Indexed: 05/22/2023]
Abstract
The fact that a protein crystal can serve as a chemical reaction vessel is intrinsically fascinating. That it can produce an electron-dense tetranuclear rhenium cluster compound from a rhenium tri-carbonyl tri-bromo starting compound adds to the fascination. Such a cluster has been synthesized previously in vitro, where it formed under basic conditions. Therefore, its synthesis in a protein crystal grown at pH 4.5 is even more unexpected. The X-ray crystal structures presented here are for the protein hen egg-white lysozyme incubated with a rhenium tri-carbonyl tri-bromo compound for periods of one and two years. These reveal a completed, very well resolved, tetra-rhenium cluster after two years and an intermediate state, where the carbonyl ligands to the rhenium cluster are not yet clearly resolved, after one year. A dense tetranuclear rhenium cluster, and its technetium form, offer enhanced contrast in medical imaging. Stimulated by these crystallography results, the unusual formation of such a species directly in an in vivo situation has been considered. It offers a new option for medical imaging compounds, particularly when considering the application of the pre-formed tetranuclear cluster, suggesting that it may be suitable for medical diagnosis because of its stability, preference of formation and biological compatibility.
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Affiliation(s)
- Alice Brink
- Department of Chemistry, University of the Free State, Nelson Mandela Drive, Bloemfontein, 9301, South Africa
- School of Chemistry, University of Manchester, Brunswick Street, Manchester M13 9PL, UK
| | - John R. Helliwell
- School of Chemistry, University of Manchester, Brunswick Street, Manchester M13 9PL, UK
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10
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Schutte-Smith M, Roodt A, Alberto R, Twigge L, Visser HG, Kirsten L, Koen R. Structures of rhenium(I) complexes with 3-hydroxyflavone and benzhydroxamic acid as O,O'-bidentate ligands and confirmation of π-stacking by solid-state NMR spectroscopy. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2019; 75:378-387. [PMID: 30957783 DOI: 10.1107/s2053229619002717] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 02/21/2019] [Indexed: 11/10/2022]
Abstract
The synthesis and crystal structures of two new rhenium(I) complexes obtained utilizing benzhydroxamic acid (BHAH) and 3-hydroxyflavone (2-phenylchromen-4-one, FlavH) as bidentate ligands, namely tetraethylammonium fac-(benzhydroxamato-κ2O,O')bromidotricarbonylrhenate(I), (C8H20N)[ReBr(C7H6NO2)(CO)3], 1, and fac-aquatricarbonyl(4-oxo-2-phenylchromen-3-olato-κ2O,O')rhenium(I)-3-hydroxyflavone (1/1), [Re(C15H9O3)(CO)3(H2O)]·C15H10O3, 3, are reported. Furthermore, the crystal structure of free 3-hydroxyflavone, C15H10O3, 4, was redetermined at 100 K in order to compare the packing trends and solid-state NMR spectroscopy with that of the solvate flavone molecule in 3. The compounds were characterized in solution by 1H and 13C NMR spectroscopy, and in the solid state by 13C NMR spectroscopy using the cross-polarization magic angle spinning (CP/MAS) technique. Compounds 1 and 3 both crystallize in the triclinic space group P-1 with one molecule in the asymmetric unit, while 4 crystallizes in the orthorhombic space group P212121. Molecules of 1 and 3 generate one-dimensional chains formed through intermolecular interactions. A comparison of the coordinated 3-hydroxyflavone ligand with the uncoordinated solvate molecule and free molecule 4 shows that the last two are virtually completely planar due to hydrogen-bonding interactions, as opposed to the former, which is able to rotate more freely. The differences between the solid- and solution-state 13C NMR spectra of 3 and 4 are ascribed to inter- and intramolecular interactions. The study also investigated the potential labelling of both bidentate ligands with the corresponding fac-99mTc-tricarbonyl synthon. All attempts were unsuccessful and reasons for this are provided.
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Affiliation(s)
- Marietjie Schutte-Smith
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Andreas Roodt
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Roger Alberto
- Department of Chemistry, University of Zürich, Winterthurerstrasse 190, Zürich CH-8057, Switzerland
| | - Linette Twigge
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Hendrik Gideon Visser
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Leo Kirsten
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
| | - Renier Koen
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa
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Lipowska M, Klenc J, Taylor AT, Marzilli LG. fac- 99mTc/Re-tricarbonyl complexes with tridentate aminocarboxyphosphonate ligands: suitability of the phosphonate group in chelate ligand design of new imaging agents. Inorganica Chim Acta 2019; 486:529-537. [PMID: 30804606 PMCID: PMC6385875 DOI: 10.1016/j.ica.2018.11.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Ligands that coordinate via dianionic phosphonate groups have not been widely utilized in radiopharmaceuticals. N-(phosphonomethyl)iminodiacetic acid (1, PMIDA) and N-(phosphonomethyl)glycine (2, PMG) were investigated as new chelators for the 99mTc/Re-tricarbonyl "core" (fac-M(CO)3, M = 99mTc, Re) present in a major class of radiopharmaceuticals. fac-M(CO)3(PMIDA) and fac-M(CO)3(PMG) complexes were studied by HPLC and 1H/13C/31P NMR methods for M = Re (Re-1 and Re-2) and by HPLC for M = 99mTc ( 99m Tc-1 and 99m Tc-2). Re-1 and 99m Tc-1 complexes exhibit a similar pH-dependent equilibrium between geometric linkage isomers (M-1a and M-1b). However, only one isomer exists for M-2 under all conditions. Structural characterization by X-ray crystallography reveals the presence of a bond between a phosphonate oxygen and the Re(I) center in fac-Re(CO)3(PMG) (Re-2). Detailed comparisons of NMR data for Re-2 conclusively demonstrate that the phosphonate group is coordinated in Re-1b (isomer favored at high pH) but not in Re-1a, which has a dangling N-(phosphonomethyl) group. To our knowledge, Re-1b and Re-2 and their 99mTc analogs are the first well-documented examples of complexes with these metal-tricarbonyl cores having a dianionic phosphonate group directly coordinated in a fac-M(CO)3-O-P grouping. Pharmacokinetic studies using Sprague-Dawley rats reveal that 99m Tc-2 is a robust tracer. Hence, phosphonate groups should be considered in designing 99mTc and 186/188Re radiopharmaceuticals, including agents with bioactive moieties attached to dangling carboxylate or phosphonate groups.
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Affiliation(s)
- Malgorzata Lipowska
- Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia 30322, United States
| | - Jeffrey Klenc
- Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia 30322, United States
| | - Andrew T. Taylor
- Department of Radiology and Imaging Sciences, Emory University, Atlanta, Georgia 30322, United States
| | - Luigi G. Marzilli
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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12
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Cyclic voltammetry, relativistic DFT calculations and biological test of cytotoxicity in walled-cell models of two classical rhenium (I) tricarbonyl complexes with 5-amine-1,10-phenanthroline. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2018.11.043] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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13
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Schutte-Smith M, Roodt A, Visser HG. Ambient and high-pressure kinetic investigation of methanol substitution in fac-[Re(Trop)(CO)3(MeOH)] by different monodentate nucleophiles. Dalton Trans 2019; 48:9984-9997. [DOI: 10.1039/c9dt01528k] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
First report of high-pressure methanol substitution by entering monodentate L forms fac-[Re(CO)3(Trop)(L)] {ΔV≠(kL) = +9 – +14 cm−3 mol−1}, indicating dissociative/dissociative interchange activation.
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Affiliation(s)
| | - Andreas Roodt
- Department of Chemistry
- University of the Free State
- PO Box 339
- Bloemfontein
- South Africa
| | - Hendrik G. Visser
- Department of Chemistry
- University of the Free State
- PO Box 339
- Bloemfontein
- South Africa
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14
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Nkoe PI, Visser HG, Swart C, Brink A, Schutte-Smith M. Synthesis of Re I tricarbonyl complexes with various sulfur- and oxygen-donating ligands: crystal structures of two Re I dinuclear structures bridged by S atoms. ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY 2018; 74:1116-1122. [PMID: 30284976 DOI: 10.1107/s205322961801207x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 08/24/2018] [Indexed: 11/10/2022]
Abstract
The synthesis and characterization of two dinuclear complexes, namely fac-hexacarbonyl-1κ3C,2κ3C-(pyridine-1κN)[μ-2,2'-sulfanediyldi(ethanethiolato)-1κ2S1,S3:2κ3S1,S2,S3]dirhenium(I), [Re2(C4H8S3)(C5H5N)(CO)6], (1), and tetraethylammonium fac-tris(μ-2-methoxybenzenethiolato-κ2S:S)bis[tricarbonylrhenium(I)], (C8H20N)[Re2(C7H7OS)3(CO)6], (2), together with two mononuclear complexes, namely (2,2'-bithiophene-5-carboxylic acid-κ2S,S')bromidotricarbonylrhenium(I), (3), and bromidotricarbonyl(methyl benzo[b]thiophene-2-carboxylate-κ2O,S)rhenium(I), (4), are reported. Crystals of (1) and (2) were characterized by X-ray diffraction. The crystal structure of (1) revealed two Re-S-Re bridges. The thioether S atom only bonds to one of the ReI metal centres, while the geometry of the second ReI metal centre is completed by a pyridine ligand. The structure of (2) is characterized by three S-atom bridges and an Re...Re nonbonding distance of 3.4879 (5) Å, which is shorter than the distance found for (1) [3.7996 (6)/3.7963 (6) Å], but still clearly a nonbonding distance. Complex (1) is stabilized by six intermolecular hydrogen-bond interactions and an O...O interaction, while (2) is stabilized by two intermolecular hydrogen-bond interactions and two O...π interactions.
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Affiliation(s)
- Pheello I Nkoe
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein, Free State, 9301, South Africa
| | - Hendrik G Visser
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein, Free State, 9301, South Africa
| | - Chantel Swart
- Department of Microbial, Biochemical and Food Biotechnology, University of the Free State, PO Box 339, Bloemfontein, Free State, 9301, South Africa
| | - Alice Brink
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein, Free State, 9301, South Africa
| | - Marietjie Schutte-Smith
- Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein, Free State, 9301, South Africa
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Frei A, Mokolokolo PP, Bolliger R, Braband H, Tsosane MS, Brink A, Roodt A, Alberto R. Self-Assembled Multinuclear Complexes Incorporating 99m Tc. Chemistry 2018; 24:10397-10402. [PMID: 29672957 DOI: 10.1002/chem.201800600] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Revised: 04/18/2018] [Indexed: 12/30/2022]
Abstract
Multinuclear complexes or clusters are rarely investigated in medicinal inorganic chemistry although they represent structural intermediates between molecules and nanomaterials. We present in this report two strategies towards 99m Tc-containing clusters. In a pre-assembly approach, the preformed but incomplete cluster fragment [Re3 (μ2 -OH)3 (μ3 -OH)(CO)9 ]- reacts with [99m Tc(CO)3 ]+ to the highly stable [99m TcRe3 (μ3 -OH)4 (CO)12 ] cube. The same structure self-assembles when reacting the mononuclear Re and 99m Tc precursors in one pot. Integrating the coordinating OH groups from Schiff bases in this concept leads straight to dinuclear, mixed-metal complexes of the type [99m TcRe(μ2 -O^N-R1 )2 (CO)6 ] in quantitative yields. Both strategies are unprecedented and open a future path towards clusters, incorporating a 99m Tc radiolabel while being decorated with targeting or cytotoxic moieties.
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Affiliation(s)
- Angelo Frei
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
| | - Pennie P Mokolokolo
- Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - Robin Bolliger
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
| | - Henrik Braband
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
| | - Mampotso S Tsosane
- Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - Alice Brink
- Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - Andreas Roodt
- Department of Chemistry, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - Roger Alberto
- Department of Chemistry, University of Zurich, Winterthurerstr. 190, CH-8057, Zurich, Switzerland
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Brink A, Kroon RE, Visser HG, van Rensburg CEJ, Roodt A. Designing model imino bifunctional chelators for radiopharmaceuticals – in vitro antitumor activity, photoluminescence and structural analysis. NEW J CHEM 2018. [DOI: 10.1039/c7nj04208f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Designed bifunctional chelators for the radionuclides of 188/186Re or 99mTc. Structure, DFT calculations, antitumor and imaging properties are described.
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Affiliation(s)
- Alice Brink
- Department of Chemistry, University of the Free State
- Bloemfontein 9300
- South Africa
| | - Robin E. Kroon
- Department of Physics, University of the Free State
- Bloemfontein 9300
- South Africa
| | - Hendrik G. Visser
- Department of Chemistry, University of the Free State
- Bloemfontein 9300
- South Africa
| | | | - Andreas Roodt
- Department of Chemistry, University of the Free State
- Bloemfontein 9300
- South Africa
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