Martine Cantuel

University of Geneva, Genève, Geneva, Switzerland

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Publications (20)126.23 Total impact

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    ABSTRACT: Due to its extreme kinetic inertness, trivalent chromium, Cr(III), has been rarely combined with labile trivalent lanthanides, Ln(III), to give discrete self-assembled (supra)molecular polynuclear complexes. However, the plethora of accessible metal-centered excited states possessing variable lifetimes and emissive properties, combined with the design of efficient intramolecular Cr(III) ↔ Ln(III) energy transfer processes open attractive perspectives for programming directional light-conversion within these heterometallic molecules. Efforts made to address this exciting challenge for both light-sensitization and light-upconversion are discussed in this article.
    Coordination Chemistry Reviews 08/2012; 256(15-16):1644-1663. DOI:10.1016/j.ccr.2011.12.013 · 12.24 Impact Factor
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    ABSTRACT: Self-assembly of the linear segmental ligand L5, consisting of a tridentate binding unit flanked with two bidentate binding units, with a mixture of Fe(II)/Ag(I) yields the trinuclear coordination-captured [2]catenate [AgFeAg(L5)(2)](4+) instead of the planned isomeric double-stranded helicate. Replacing the octahedral (Fe(II)) and tetrahedral (Ag(I)) cations with Zn(II), which is compatible with both geometries, gives intricate mixtures of homometallic complexes upon reaction with the twin ligand L6, from which the macrocyclic dinuclear complex [Zn(2)(L6)](4+) can be isolated. Application of the thermodynamic site binding model attributes the origin of the ligand preference for producing single-stranded macrocycles, the precursors of the trinuclear catenate, to the abnormally low value of the effective molarity controlling the intramolecular connection leading to the usual double-stranded helical isomer.
    Dalton Transactions 05/2012; 41(24):7218-26. DOI:10.1039/c2dt30414g · 4.20 Impact Factor
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    ABSTRACT: BF(2)-Azadipyrromethene dyes are a promising class of NIR emitter (nonhalogenated) and photosensitizer (halogenated). Spectroscopic studies on a benchmark example of each type, including absorption (one and two photon), time-resolved transient absorption (ps-ms) and fluorescence, are reported. Fast photodynamics reveal that intense nanosecond NIR fluorescence is quenched in a brominated analog, giving rise to a persistent (21 μs) transient absorption signature. Kinetics for these changes are determined and ascribed to the efficient population of a triplet state (72%), which can efficiently sensitize singlet oxygen formation (ca. 74%), directly observed by (1)Δ(g) luminescence. Photostability measurements reveal extremely high stability, notably for the nonhalogenated variant, which is at least 10(3)-times more stable (Φ(photodeg.) = < 10(-8)) than some representative BODIPY and fluorescein dyes.
    The Journal of Physical Chemistry A 12/2011; 115(48):14034-9. DOI:10.1021/jp2077775 · 2.69 Impact Factor
  • Joe Chahine · Nathalie Saffon · Martine Cantuel · Suzanne Fery-Forgues ·
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    ABSTRACT: The salt formed between the large aromatic berberine cation and the long-chain palmitate anion was synthesized and used to prepare aqueous suspensions of particles owing to a solvent-exchange method. Under these conditions, elongated particles were readily obtained. They were studied by transmission microscopy with polarized light, as well as by fluorescence and electron microscopy. They were shown to be probably crystallized nanofibers, which were stable in suspension. Unexpectedly, upon filtration and drying, these fibers evolved to give a reticulated solid. The fluorescence properties of the compound were analyzed in solution, in aqueous suspension and in the powder crystalline state. Interestingly, berberine palmitate is virtually not fluorescent in aqueous solution because of the quenching effect of water, but transition to the solid state was accompanied by a strong increase in fluorescence intensity. This phenomenon was explained by the original molecular arrangement in the solid state. Actually, in the crystal, the anions form a distinct layer, which limits parallel-stacking of the fluorescent cations. Moreover, the berberine cations are protected from the access of water molecules, and so no quenching effect can take place. This example confirms that the newly introduced concept of ion-pair aggregation-induced fluorescence enhancement can be extended to a variety of structures. It also shows the interest of ion pairs for preparing fluorescent nanofibers and reticulated solids using a solvent-exchange method that is particularly easy to implement.
    Langmuir 02/2011; 27(6). DOI:10.1021/la104302d · 4.46 Impact Factor
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    ABSTRACT: A series of structurally well-defined enantiopure tripodal allyl dendritic structures bearing three amine groups have been synthesized. The hydrogenation of the allyl groups in the presence of a Pd/C catalyst gave the corresponding enantiopure n-propyl counterparts. Treatment of these n-propyl amino dendrimers with heteropolyacid H3PW12O40 and excess H2O2 gave the enantiopure n-propyl {PO4[WO(O2)2]4}3– salts. Characterization of these dendritic POM hybrids in solution by NMR spectroscopy, elemental analysis, UV/Vis spectrophotometry, circular dichroism (CD), vibrational circular dichroism (VCD) and fluorimetry indicates the presence of POM–ligand interactions and confirms their optical and chiroptical properties. The hybrid compounds selectively oxidized sulfides to the corresponding chiral sulfoxides with up to 13 % enantiomeric excess (ee), highlighting the transfer of chirality from the dendritic wedges to the inorganic cluster. The properties of the POM anion, especially its solubility and regio- and stereoselectivity, are sensitive to the structure of the cation. The catalyst was recovered by precipitation without any discernible loss in activity, selectivity or enantioselectivity over three catalytic cycles at –50 °C. Interestingly, a dendritic effect was noted in the enantioselectivity as the dendritic-POM hybrids are more selective than their non-dendritic counterparts. The ee resulting from chirality transfer to the anionic POM unit is comparable to that obtained in our previous work with monopodal dendritic polyoxometalates (14 %) despite the polyvalency of the highly charged tripodal ligand, which is rationalized by different spectroscopic methods.
    Berichte der deutschen chemischen Gesellschaft 02/2011; 2011(5). DOI:10.1002/ejic.201001111 · 2.94 Impact Factor
  • Suzanne Fery-Forgues · Martine Cantuel · Clara Fournier-Noël ·
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    ABSTRACT: The unexpected formation of nanocrystals in dilute dye solutions was revealed using the hydrophobic dye, 7-methoxycoumarin, the spectroscopic behavior of which has been frequently studied in water; comparison was made with the water-soluble, sulfonated analogue. A solution of the dye at 10−5 M concentration range was found to be a suspension of nanocrystals; at concentrations of 1 × 10−4 M, > 70% dye was in the form of nanocrystals. Surprisingly, the presence of these nanocrystals was difficult to detect by routine absorbance and fluorescence spectroscopy and was mainly noticeable by measurement of fluorescence quantum yield, as the nanocrystals were poorly emissive compared to dissolved dye molecules; electron microscopy and dynamic light scattering gave clear evidence for the presence of nanocrystals. This article illustrates the fact that the formation of nanocrystals, although abundant, may easily go unnoticed.
    Dyes and Pigments 11/2010; 87(3):241-248. DOI:10.1016/j.dyepig.2010.04.002 · 3.97 Impact Factor
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 04/2010; 41(17). DOI:10.1002/chin.201017253
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    ABSTRACT: Photoliberation of a caged, chelating naphthalene antenna greatly enhances the luminescence of a Eu(III)-cyclen complex due to metal-bound water displacement and sensitization by the antenna, giving a lanthanide-labelling strategy in different media, being optimal in the presence of a TMADS surfactant.
    Chemical Communications 04/2010; 46(14):2486-8. DOI:10.1039/b919899g · 6.83 Impact Factor
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    ABSTRACT: A strategy to manage energy, following light absorption, and modulate excited-state properties, including luminescence lifetimes of multicomponent photoactive systems, is presented. The intervening mechanism, which is illustrated through the use of bi-/multi-chromophoric molecules, relies on energy shuttling between different matched chromophores under kinetic and thermodynamic control. This tutorial review is destined to show supramolecular and materials chemists, spectroscopists and nanoscientists how to harness reversible electronic energy transfer in a predictable fashion in designer molecule-based systems.
    Chemical Society Reviews 02/2010; 39(2):506-15. DOI:10.1039/b810669j · 33.38 Impact Factor
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    ABSTRACT: The synthesis and characterization of four enantiopure polyoxometalate- cored dendrimers, which contain n-propyl and epoxy groups, based on electrostatic interactions between enantiopure dendritic quaternary ammonium ions and an a chiral trianionic POM has been reported. The optical and chiroptical properties of the n-propyl-terminated POM-cored dendrimers have been demonstrated in solution by UV/Vis spectroscopy, circular dichroism (CD) and vibrational circular dichroism (VCD) spectroscopy, and fluorimetry. The solution CD, UV/Vis and VCD data indicate a significant induced optical activity in the POM cluster. The appropriate elaboration of optimized dendritic structures enabled the use of a range of POM species, and represented a promising approach to efficient, recoverable, and highly enantioselective dendritic POM future catalysts.
    Chemistry - A European Journal 08/2009; 15(35):8703-8. DOI:10.1002/chem.200901512 · 5.73 Impact Factor
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    ABSTRACT: Homoleptic copper(I) bis(2,9-dialkyl-1,10-phenanthroline) units, as well as a range of related heteroleptic species, represent popular choices for building blocks in the construction of supramolecular edifices and photo- and electroactive devices. The photophysical properties of these traditionally underperforming luminescent complexes can be dramatically modified in a qualitatively predictable fashion through ligand design, the use of bichromophoric ligands, and by reconstitution of the primary coordination sphere. An overview of key excited-state processes established in these complexes is presented, with particular emphasis on recent developments and insights, as well as ramifications for developing successful strategies to prolong luminescence lifetimes and increase quantum yields.
    Coordination Chemistry Reviews 12/2008; 252(23-252):2572-2584. DOI:10.1016/j.ccr.2008.03.013 · 12.24 Impact Factor
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    ABSTRACT: The segmental bidentate-tridentate-bidentate ligand L2 reacts with M(II) (M = Cr, Zn) and Ln(III) (Ln = La, Eu, Gd, Tb, Lu) to give the heterotrimetallic triple-stranded helicates [MLnM(L2)3]7+. For M = Zn(II), the isolated complexes [ZnLnZn(L2)3](CF3SO3)7 (Ln = Eu, Tb) display only lanthanide-centred luminescence arising from the pseudo-tricapped trigonal prismatic LnN9 coordination site. For M = Cr(II), rapid air oxidation provides Cr(III) and leads to the isolation of inert [CrLnCr(L2)3](CF3SO3)9 (Ln = Eu, Tb) complexes, in which divergent intramolecular Ln --> Cr energy transfers can be evidenced. Taking [ZnEuZn(L2)3]7+ as a luminescent standard for Eu-centred emission, a quantitative treatment of the energy migration processes indicates that the rate constant characterizing the Eu --> Cr energy transfer is more efficient in the trimetallic system, than in the analogous simple bimetallic edifice. Particular attention is focused on potential control of directional energy transfer processes in Cr-Ln pairs.
    Dalton Transactions 07/2006; 2006(22):2647-60. DOI:10.1039/b602392d · 4.20 Impact Factor
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    ABSTRACT: Circularly polarized luminescence (CPL) from selected transitions of Eu(III) in resolved single crystals of Na3[Eu(ODA)3].2NaClO4.6H2O are compared to CPL results obtained from solutions containing perturbed racemic mixtures of Eu(2,6-pyridine-dicarboxylate)3 (3-) and enantiomerically pure d-f helicate LambdaLambda-(-)EuCr(L8)3] in order to determine an empirical relationship between helicity and CPL spectra. Comparison of the CPL results, even for the magnetic dipole allowed transitions of Eu(III) where one measures large chiral discrimination, shows that the signs and magnitudes do not correlate with the overall helicity of the Eu(III) site. It is concluded that the symmetry of the Eu(III) site in LambdaLambda-(-)EuCr(L8)3 is not close enough to D3 to allow for the confirmation of the presumed spectra:structure correlation.
    Chirality 01/2006; 18(6):406-12. DOI:10.1002/chir.20270 · 1.89 Impact Factor
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    ABSTRACT: Inert and optically active pseudo-octahedral Cr(III)N6 and Ru(II)N6 chromophores have been incorporated by self-assembly into heterobimetallic triple-stranded helicates HHH-[CrLnL3]6+ and HHH-[RuLnL3]5+. The crystal structures of [CrLnL(3)](CF(3)SO(3))(6) (Ln=Nd, Eu, Yb, Lu) and [RuLnL3](CF3SO3)5 (Ln=Eu, Lu) demonstrate that the helical structure can accommodate metal ions of different sizes, without sizeable change in the intermetallic MLn distances. These systems are ideally suited for unravelling the molecular factors affecting the intermetallic nd-->4f communication. Visible irradiation of the Cr(III)N6 and Ru(II)N6 chromophores in HHH-[MLnL3]5/6+ (Ln=Nd, Yb, Er; M=Cr, Ru) eventually produces lanthanide-based near infrared (NIR) emission, after directional energy migration within the complexes. Depending on the kinetic regime associated with each specific d-f pair, the NIR luminescence decay times can be tuned from micro- to milliseconds. The origin of this effect, together with its rational control for programming optical functions in discrete heterobimetallic entities, are discussed.
    Chemistry 05/2005; 11(11):3228-42. DOI:10.1002/chem.200401158 · 5.73 Impact Factor
  • Shane G Telfer · Nobuo Tajima · Reiko Kuroda · Martine Cantuel · Claude Piguet ·
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    ABSTRACT: We have investigated the CD spectra of a series of enantiomerically pure heterobimetallic helicates, Lambda,Lambda-[LnCr(1)(3)](6+) (Ln = Eu, Gd, Tb), which contain segmental di-imine ligands. For the mononuclear precursor of these helicates, Lambda-[Cr(1)(3)](3+), a positive exciton couplet was observed around 330 nm, as expected for a tris(di-imine) complex with this absolute configuration. The titration of Ln(III) ions into a solution of this complex leads to the formation of Lambda,Lambda-[LnCr(1)(3)](6+). During this process, the CD signal was observed to invert to give a signal which was negative at lower energies. We investigated the observed changes in the CD spectra using a ZINDO-based computational method which we have previously developed. We were able to show that the exciton coupling of the chromophores coordinated to the Cr and Ln ions give rise to CD signals of opposite phase, despite having the same nominal absolute configuration. Exciton coupling between chromophores located on different metal centers ("internuclear" exciton coupling) is also predicted to have a significant impact on the observed spectrum. We were able to "deconstruct" the observed CD spectra into a set of competing exciton coupling effects and show that the sign of these spectra does not correlate with the absolute configuration of the individual metal centers.
    Inorganic Chemistry 09/2004; 43(17):5302-10. DOI:10.1021/ic049540d · 4.76 Impact Factor
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    ABSTRACT: Decomplexation of the trivalent lanthanide, Ln(III), from the racemic bimetallic triple-stranded helicates [LnCr(L8)(3)](6+) provides the inert chiral tripodal nonadentate receptor [Cr(L8)(3)](3+). Elution of the latter podand with Na(2)Sb(2)[(+)-C(4)O(6)H(2)](2).5H(2)O through a cation exchange column allows its separation into its inert helical enantiomers M-(+)(589)-[Cr(L8)(3)](3+) and P-(-)(589)-[Cr(L8)(3)](3+), whose absolute configurations are assigned by using CD spectroscopy and exciton theory. Recombination with Ln(III) restores the original triple-stranded helicates [LnCr(L8)(3)](6+), and the associated thermodynamic parameters unravel the contribution of electrostatic repulsion and preorganization to the complexation process. Combining M-(+)(589)-[Cr(L8)(3)](3+) with Eu(III) produces the enantiomerically pure d-f helicate MM-(-)(589)-[EuCr(L8)(3)](CF(3)SO(3))(6).4CH(3)CN, whose X-ray crystal structure (EuCrC(113)H(111)N(25)O(21)S(6)F(18), monoclinic, P2(1), Z = 2) unambiguously confirms the absolute left-handed configuration for the final helix. The associated ligand-centered and metal-centered chiro-optical properties recorded for the complexes MM-[LnCr(L8)(3)](6+) and PP-[LnCr(L8)(3)](6+) (Ln = Eu, Gd, Tb) show a strong effect of helicity on specific rotary dispersions, CD and CPL spectra.
    Inorganic Chemistry 04/2004; 43(6):1840-9. DOI:10.1021/ic035292u · 4.76 Impact Factor
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    ABSTRACT: A [Cr(alpha,alpha'-diimine)3]3+ chromophore is used as a donor for sensitizing NdIII and YbIII near-infrared (NIR) emitters in the heterobimetallic helicates [LnCrIIIL3]6+. The intramolecular CrIII --> LnIII energy transfer process controls the population of the lanthanide-centered emitting levels, thus leading to unprecedented extension of the NIR luminescence decay times in the millisecond range for Nd and Yb ions incorporated in coordination complexes.
    Journal of the American Chemical Society 12/2003; 125(51):15698-9. DOI:10.1021/ja0386501 · 12.11 Impact Factor
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    ABSTRACT: Stoichiometric mixing of the segmental ligand 2-{6-[N,N-diethylcarboxamido]pyridin-2-yl}-1,1′-dimethyl-5,5′-methylene-2′-(5-methylpyridin-2-yl)bis[1H-benzimidazole] (L) with Ln(CF3SO3)3 (Ln = La–Lu) and Cr(CF3SO3)2 under an inert atmosphere produces quantitatively the self-assembled triple-stranded non-covalent podates (HHH)-[LnCrIIL3]5+. Air oxidation of the low-spin CrII complexes gives selectively the head-to-head-to-head podates (HHH)-[LnCrIIIL3]6+ into which inert CrIII has been incorporated. The X-ray crystal structures of [LnCrIII(L)3](CF3SO3)6(CH3CN)4 (Ln = Eu, 7; Ln = Lu, 8) confirm the formation of regular triple-helical cations (HHH)-[LnCrIIIL3]6+ whose structure is maintained in acetonitrile according to ESI–MS, spectrophotometry and NMR data. Photophysical studies evidence efficient sensitization of both EuIII and CrIII through ligand excitation at low temperature, while a subsequent intramolecular EuIII → CrIII energy transfer (η = 70%) limits Eu-centred luminescence and induces directional light-conversion along the three-fold axis, resulting in CrIII emission. For (HHH)-[TbCrIIIL3]6+, the better spectral overlap between the emission spectrum of TbIII (5D4 → 7FJ) and the absorption spectrum of CrIII (4A2 → 4T2) provides a quantitative TbIII → CrIII energy transfer (η ≥ 99%) and long-range intermetallic communication. De-complexation of LnIII with water or EDTA4− gives the first inert and optically active-CrIII-containing triple-helical nonadentate receptor (HHH)-[CrIIIL3]3+.
    Journal of the Chemical Society Dalton Transactions 04/2002; 2002(9). DOI:10.1039/B200011C · 4.10 Impact Factor
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    Martine Cantuel ·
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    ABSTRACT: Ce travail de thèse présente l'étude des complexes hétérométalliques [LnCr(L1)3]6+, [LnCr2(L7)3]9+ et [LnZn2(L7)]3]7+, formés par auto-assemblage avec les ligands L1; et L7. L'insertion de l'ion CrIII dans ces triples hélices a permis d'observer de nouvelles propriétés, dues à son inertie et à sa structure électronique. Les complexes [LnCr(L1)3]6+ sont luminescents et, suivant l'ion lanthanide utilisé, des conversions de lumière interviennent, par transferts d'énergie intramoléculaires du lanthanide vers le chrome, lorsque Ln=Eu ou Tb, ou du chrome vers le lanthanide, lorsque Ln=Nd ou Yb. L'inertie de l'ion CrIII a permis l'isolation des premiers complexes énantiomères de lanthanides, qui soient stables et luminescents sans posséder de centre stéréogénique: MM-[LnCr(L1)3]6+ et PP-[LnCr(L1)3]6+. Les complexes [LnM2(L7)3]7/9+, dans lesquels l'ion LnIII central est entouré par les deux ions de transition, promettent l'observation d'intéressantes propriétés, notamment lorsque M=CrIII, où la triple hélice est totalement inerte et possède trois centres luminescents.

Publication Stats

791 Citations
126.23 Total Impact Points


  • 2002-2012
    • University of Geneva
      • Department of Inorganic, Analytical, and Applied Chemistry
      Genève, Geneva, Switzerland
  • 2010-2011
    • University of Bordeaux
      Burdeos, Aquitaine, France
    • Université Bordeaux 1
      • UMR ISM - Institut des Sciences Moléculaires
      Talence, Aquitaine, France
  • 2008
    • French National Centre for Scientific Research
      Lutetia Parisorum, Île-de-France, France