Synthesis of a Europium Complex for Anion‐Sensing Involving Regioselective Substitution of Cyclen

Yu, Junhua; Parker, David

doi:10.1002/ejoc.200500432

Cited by 22 publications

(6 citation statements)

References 24 publications

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“…[29,30] The carboxylic acid substituent 1 was obtained from bromoacetyl bromide and 6-aminocaproic acid (Scheme 2), while the phenacyl pendant 3 was synthesised as previously described. [25] One amine function of cyclen was protected by the method of Platzek et al for 1,7-substituted cyclens: [31] N,N-dimethylformamide dimethylacetal (DMF-DMA) was treated with cyclen to produce 1,4,7,10-tetraazatricyclo- A C H T U N G T R E N N U N G [5.5.1.0]tridecane (2 a) in almost quantitative yield and upon careful hydrolysis at low temperature this produced the formaldehyde-protected material 2 b.…”

Section: Resultsmentioning

confidence: 99%

Non‐Cytotoxic, Bifunctional Eu^III and Tb^III Luminescent Macrocyclic Complexes for Luminescence Resonant Energy‐Transfer Experiments

Ferrand

Imbert

Chauvin

et al. 2007

Chemistry A European J

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A new macrocyclic ligand, L3, has been synthesised, based on the cyclen framework grafted with three phenacyl light-harvesting groups and a C5-alkyl chain bearing a carboxylic acid function as a potential linker for biological material. Acidity constants are determined by spectrophotometric titrations, as well as conditional stability constants for the resulting 1:1 complexes with trivalent lanthanide ions. The complexes have stabilities comparable to 1,4,7,10-tetrakis(carbamoylmethyl)-1,4,7,10-tetraazacyclododecane (dtma) complexes, with pLn approximately 12-13. Photophysical properties of the ligand and of the EuL3 and TbL3 complexes have been determined for both microcrystalline samples and solutions in water and acetonitrile. They point to the metal ion being present in an environment with axial symmetry derived from the C4 point group. The hydration number determined for TbL3 decreases with increasing pH value and becomes fractional at pH 7.5, which points to an equilibrium between two differently solvated species and probably to the participation of the deprotonated carboxylic acid chain in the complexation. The quantum yields in water (1.9% for EuIII, 3.4% for TbIII) are smaller than those for complexes with the symmetrically substituted parent macrocycle, but efficient luminescence resonant energy transfer (LRET) was observed when Cy5 dye was added to the solutions. Finally, the influence of the TbL3 complex on cell viability is tested on both malignant (5D10 mouse hybridoma, Jurkat human T leukaemia, MCF-7 human breast carcinoma) and non-malignant (Hacat human keratinocyte) cell lines. Cell viability after 24 h incubation at 37 degrees C with 500 microM TbL3 was >90% for all cell lines, except Jurkat (>70%). All of these properties make LnL3 complexes interesting potential probes for bioanalyses.

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Section: Resultsmentioning

confidence: 99%

Non‐Cytotoxic, Bifunctional Eu^III and Tb^III Luminescent Macrocyclic Complexes for Luminescence Resonant Energy‐Transfer Experiments

Ferrand

Imbert

Chauvin

et al. 2007

Chemistry A European J

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“…251 Eu-based luminescence from a Eu/DO3A complex with a binaphthyl pendant group as chromophore is enhanced on binding to HSA, because the hydrophobic environment around the binaphthyl group lowers its 3 p-p* energy nearer to the relevant f-f state of Eu(III). 252 Eu/DO3A derivatives have been prepared which can act as ratiometric luminescent sensors for biologically-relevant anions such as malate 253 and citrate. 254 Circular dichroism has been detected for the first time using luminescence spectroscopy, for the (racemic) chiral complex [Eu(dipicolinate) 3 ] 3which has D 3 symmetry.…”

Section: Metalloporphyrin Complexesmentioning

confidence: 99%

Photophysical properties of metal complexes

Ward

2006

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

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“…Alkylation using reactive organohalides has been the method of choice for the derivatisation of cyclen and this method has produced ligands for lanthanides, such as europium and terbium, which have been used as the basis for luminescent probes and sensors [ 8 , 16 , 17 , 18 ], and gadolinium that has been employed as contrast agents for MRI [ 11 , 19 , 20 ]. Typically, these synthetic approaches have produced symmetrical tetrasubstituted ligands, although there are examples of tri substituted cyclen derivatives producing coordinatively unsaturated lanthanide complexes for use as anion sensors [ 21 , 22 ]. Examples of disubstituted ligands are rarer, as the resulting complexes lack the required stability in solution [ 23 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Organosilicon Ligands for Europium (III) and Gadolinium (III) as Potential Imaging Agents

et al. 2020

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The relaxivity of MRI contrast agents can be increased by increasing the size of the contrast agent and by increasing concentration of the bound gadolinium. Large multi-site ligands able to coordinate several metal centres show increased relaxivity as a result. In this paper, an “aza-type Michael” reaction is used to prepare cyclen derivatives that can be attached to organosilicon frameworks via hydrosilylation reactions. A range of organosilicon frameworks were tested including silsesquioxane cages and dimethylsilylbenzene derivatives. Michael donors with strong electron withdrawing groups could be used to alkylate cyclen on three amine centres in a single step. Hydrosilylation successfully attached these to mono-, di-, and tri-dimethylsilyl-substituted benzene derivatives. The europium and gadolinium complexes were formed and studied using luminescence spectroscopy and relaxometry. This showed the complexes to contain two bound water moles per lanthanide centre and T1 relaxation time measurements demonstrated an increase in relaxivity had been achieved, in particular for the trisubstituted scaffold 1,3,5-tris((pentane-sDO3A)dimethylsilyl)benzene-Gd3. This showed a marked increase in the relaxivity (13.1 r1p/mM−1s−1).

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Synthesis of a Europium Complex for Anion‐Sensing Involving Regioselective Substitution of Cyclen

Abstract: A regioselective synthetic route that allows the construction of tri-functionally substituted cyclen is described. This facilitates the synthesis of a europium complex that exhibits a good photoresponse to malate, forming the basis of a chemoselective sensor.

Cited by 22 publications

References 24 publications

Non‐Cytotoxic, Bifunctional Eu^III and Tb^III Luminescent Macrocyclic Complexes for Luminescence Resonant Energy‐Transfer Experiments

Non‐Cytotoxic, Bifunctional Eu^III and Tb^III Luminescent Macrocyclic Complexes for Luminescence Resonant Energy‐Transfer Experiments

Photophysical properties of metal complexes

Synthesis of Organosilicon Ligands for Europium (III) and Gadolinium (III) as Potential Imaging Agents

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Synthesis of a Europium Complex for Anion‐Sensing Involving Regioselective Substitution of Cyclen

Abstract: A regioselective synthetic route that allows the construction of tri-functionally substituted cyclen is described. This facilitates the synthesis of a europium complex that exhibits a good photoresponse to malate, forming the basis of a chemoselective sensor.

Cited by 22 publications

References 24 publications

Non‐Cytotoxic, Bifunctional EuIII and TbIII Luminescent Macrocyclic Complexes for Luminescence Resonant Energy‐Transfer Experiments

Non‐Cytotoxic, Bifunctional EuIII and TbIII Luminescent Macrocyclic Complexes for Luminescence Resonant Energy‐Transfer Experiments

Photophysical properties of metal complexes

Synthesis of Organosilicon Ligands for Europium (III) and Gadolinium (III) as Potential Imaging Agents

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Non‐Cytotoxic, Bifunctional Eu^III and Tb^III Luminescent Macrocyclic Complexes for Luminescence Resonant Energy‐Transfer Experiments

Non‐Cytotoxic, Bifunctional Eu^III and Tb^III Luminescent Macrocyclic Complexes for Luminescence Resonant Energy‐Transfer Experiments