Publications by authors named "Lise-Marie Chamoreau"

64 Publications

Mapping C-H⋅⋅⋅M Interactions in Confined Spaces: (α-ICyD )Au, Ag, Cu Complexes Reveal "Contra-electrostatic H Bonds" Masquerading as Anagostic Interactions*.

Chemistry 2021 Jun 6;27(31):8127-8142. Epub 2021 May 6.

Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, UMR 8232, 4 place Jussieu, 75005, Paris, France.

What happens when a C-H bond is forced to interact with unpaired pairs of electrons at a positively charged metal? Such interactions can be considered as "contra-electrostatic" H-bonds, which combine the familiar orbital interaction pattern characteristic for the covalent contribution to the conventional H-bonding with an unusual contra-electrostatic component. While electrostatics is strongly stabilizing component in the conventional C-H⋅⋅⋅X bonds where X is an electronegative main group element, it is destabilizing in the C-H⋅⋅⋅M contacts when M is Au(I), Ag(I), or Cu(I) of NHC-M-Cl systems. Such remarkable C-H⋅⋅⋅M interaction became experimentally accessible within (α-ICyD )MCl, NHC-Metal complexes embedded into cyclodextrins. Computational analysis of the model systems suggests that the overall interaction energies are relatively insensitive to moderate variations in the directionality of interaction between a C-H bond and the metal center, indicating stereoelectronic promiscuity of fully filled set of d-orbitals. A combination of experimental and computational data demonstrates that metal encapsulation inside the cyclodextrin cavity forces the C-H bond to point toward the metal, and reveals a still attractive "contra-electrostatic" H-bonding interaction.
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http://dx.doi.org/10.1002/chem.202100263DOI Listing
June 2021

The Atypical Hysteresis of [Fe(C F Tp) ]: Overlay of Spin-Crossovers and Symmetry-Breaking Phase Transition.

Angew Chem Int Ed Engl 2021 Apr 5;60(16):8803-8807. Epub 2021 Mar 5.

Institut Parisien de Chimie Moléculaire, CNRS UMR 8232, Sorbonne Université, 4 place Jussieu, 75252, Paris cedex 5, France.

The [Fe (C F Tp) ] spin-crossover complex is an atypical molecular switch, which can be converted upon annealing between two archetypal spin-crossover behaviours: from an extremely gradual spin-crossover to a broad hysteretic spin-transition (of ca. 65 K). The hysteresis shows an uncommon "rounded shape" that is reproducible upon cycling temperature. In depth structural studies reveal a first crystal phase transition, which occurs upon melting and recrystallizing at high temperature. This first irreversible transition is associated with a radical change in the crystal packing. More importantly, the "rounded and broad" hysteretic transition is shown to occur in a non-cooperative SCO system and is associated with the occurrence of a symmetry-breaking phase transition that appears when roughly ca. 50 % of the SCO complexes are switched.
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http://dx.doi.org/10.1002/anie.202015994DOI Listing
April 2021

Solvothermal synthesis, structure and magnetic properties of heterometallic coordination polymers based on a phenolato-oxamato co-bidentate-tridentate ligand.

Dalton Trans 2021 Jan;50(2):681-688

Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, F-75252, Paris, France.

The use of solvothermal conditions has succesfully led to the preparation of heterometallic 1D coordination polymers from a co-bidentate-tridentate phenolato-oxamato ligand. The reaction of the N-(2-hydoxyphenyl)oxamic acid (ohpma) with acetate salts of transition metal ions at 80 °C has yielded the heterobimetallic [Cu(ohpma)M(OAc)(DMF)2] (M = Co (1); Mn (2)) and the heterotrimetallic [Cu(ohpma)Co0.57Mn0.43(OAc)(DMF)2] (3) chain compounds. Single-crystal and powder diffraction studies show that the polymers are isostructural. Magnetic studies suggest the existence of an inter-chain two-dimensional antiferromagnetic interaction taking place in compounds 1-3.
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http://dx.doi.org/10.1039/d0dt03269gDOI Listing
January 2021

Insights into the antiproliferative mechanism of (C^N)-chelated half-sandwich iridium complexes.

Dalton Trans 2020 Dec;49(48):17635-17641

Institut Parisien de Chimie Moléculaire (IPCM), Sorbonne Université, CNRS, 4 place Jussieu, F-75005 Paris, France.

Transition metal-based anticancer compounds, as an alternative to platinum derivatives, are raising scientific interest as they may present distinct although poorly understood mechanisms of action. We used a structure-activity relationship-based methodology to investigate the chemical and biological features of a series of ten (C^N)-chelated half-sandwich iridiumIII complexes of the general formula [IrCp*(phox)Cl], where (phox) is a 2-phenyloxazoline ligand forming a 5-membered metallacycle. This series of compounds undergoes a fast exchange of their chlorido ligand once solubilised in DMSO. They were cytotoxic to HeLa cells with IC50 values in the micromolar range and induced a rapid activation of caspase-3, an apoptosis marker. In vitro, the oxidative power of all the complexes towards NADH was highlighted but only the complexes bearing substituents on the oxazoline ring were able to produce H2O2 at the micromolar range. However, we demonstrated using a powerful HyPer protein redox sensor-based flow cytometry assay that most complexes rapidly raised intracellular levels of H2O2. Hence, this study shows that oxidative stress can partly explain the cytotoxicity of these complexes on the HeLa cell line and gives a first entry to their mechanism of action.
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http://dx.doi.org/10.1039/d0dt03414bDOI Listing
December 2020

Correction: Thermo- and electro-switchable Cs⊂{Fe-Fe} cubic cage: spin-transition and electrochromism.

Chem Commun (Camb) 2020 Sep;56(73):10770

Institut Parisien de Chimie Moléculaire, UMR CNRS 8232, Sorbonne Université, 4 place Jussieu, 750005 Paris, France.

Correction for 'Thermo- and electro-switchable Cs⊂{Fe4-Fe4} cubic cage: spin-transition and electrochromism' by Jana Glatz et al., Chem. Commun., 2020, DOI: 10.1039/d0cc04279j.
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http://dx.doi.org/10.1039/d0cc90383cDOI Listing
September 2020

Thermo- and electro-switchable Cs⊂{Fe-Fe} cubic cage: spin-transition and electrochromism.

Chem Commun (Camb) 2020 Sep;56(74):10950-10953

Institut Parisien de Chimie Moléculaire, UMR CNRS 8232, Sorbonne Université, 4 place Jussieu, 750005 Paris, France.

A mixed valence Cs⊂{Fe4-Fe4} cyanido-cube was synthesized and structurally characterized. The molecule, which is robust in solution, shows remarkable electronic versatility. Electrochromic properties associated with nine different electronic states are observed in solution together with a thermo-induced spin-transition in the solid state.
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http://dx.doi.org/10.1039/d0cc04279jDOI Listing
September 2020

Dual switchable molecular tweezers incorporating anisotropic Mn-salphen complexes.

Dalton Trans 2020 Jul;49(26):8872-8882

Sorbonne Université, UMR CNRS 8232, Institut Parisien de Chimie Moléculaire, 4 place Jussieu, 75005, Paris, France.

An alternative strategy for the synthesis of terpyridine based switchable molecular tweezers has been developed to incorporate anisotropic Mn(iii)-salphen complexes. The free ligand was synthesized using a building block strategy based on Sonogashira coupling reactions and was then selectively metalated with manganese in a last step. The conformation of the tweezers was switched from an open 'W' shaped form to a closed 'U' form by Zn(ii) coordination to the terpyridine unit bringing the two Mn-salphen moieties in close spatial proximity as confirmed by X-ray crystallography. An alternate switching mechanism was observed by the intercalation of a bridging cyanide ligand between the two Mn-salphen moieties that resulted in the closing of the tweezers. These dual stimuli are attractive for achieving multiple controls of the mechanical motion of the tweezers. A crystallographic structure of unexpected partially oxidized closed tweezers was also obtained. One of the two Mn-salphen moieties underwent a ligand-centered oxidation of an imino to an amido group allowing an intramolecular Mn-Oamide-Mn linkage. The magnetic properties of the manganese(iii) dimers were investigated to evaluate the magnetic exchange interaction and analyze the single molecule magnet behavior.
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http://dx.doi.org/10.1039/d0dt01465fDOI Listing
July 2020

Permethylated NHC-Capped α- and β-Cyclodextrins (ICyD ) Regioselective and Enantioselective Gold-Catalysis in Pure Water.

Chemistry 2020 Dec 7;26(68):15901-15909. Epub 2020 Oct 7.

Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire (IPCM), UMR 8232, 4, place Jussieu, 75005, Paris, France.

A series of water-soluble encapsulated copper(I), silver(I) or gold(I) complexes based on NHC-capped permethylated cyclodextrins (ICyD ) were developed and used as catalysts in pure water for hydration, lactonization, hydroarylation and cycloisomerization reactions. ICyD ligands gave cavity-based high regioselectivity in hydroarylations, and high enantioselectivities in gold-catalyzed cycloisomerizations reactions giving up to 98 % ee in water. These ICyD are therefore useful ligands for selective catalysis in pure water.
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http://dx.doi.org/10.1002/chem.202001990DOI Listing
December 2020

Electron Transfer in the Cs⊂{Mn Fe } Cubic Switch: A Soluble Molecular Model of the MnFe Prussian-Blue Analogues.

Angew Chem Int Ed Engl 2020 May 25;59(21):8089-8093. Epub 2020 Feb 25.

Institut Parisien de Chimie Moléculaire-CNRS UMR 8232, UPMC-Paris 6, Sorbonne Université, 4 place Jussieu, 75252, Paris cedex 05, France.

A mixed-valence {Mn Mn Fe Fe } cyanide-bridged molecular cube hosting a caesium cation, Cs⊂{Mn Fe }, was synthesized and structurally characterized by X-ray diffraction. Cyclic-voltammetry measurements show that its electronic state can be switched between five different redox states, which results in a remarkable electrochromic effect. Magnetic measurements on fresh samples point to the occurrence of a spin-state change near room temperature, which could be ascribed to a metal-to-metal electron transfer converting the {Fe -CN-Mn } pair into a {Fe -CN-Mn } pair. This feature was only previously observed in the polymeric MnFe Prussian-blue analogues (PBAs). Moreover, this novel switchable molecule proved to be soluble and stable in organic solvents, paving the way for its integration into advanced materials.
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http://dx.doi.org/10.1002/anie.201916199DOI Listing
May 2020

Polymerization of rac-Lactide Using Achiral Iron Complexes: Access to Thermally Stable Stereocomplexes.

Angew Chem Int Ed Engl 2019 09 12;58(36):12585-12589. Epub 2019 Apr 12.

Chimie ParisTech, PSL University, CNRS, Institut de Recherche de Chimie Paris, 75005, Paris, France.

Enantiopure poly(lactic acid) (PLA) can form stereocomplexes when enantiomeric PLA chains are mixed in equivalent amounts. Such materials provide interesting features that might be suitable for numerous applications. Despite several advantages, the main drawback of PLA is its narrow window of processing, thus limiting its use for industrial applications. Reported herein are achiral iron complexes, that are highly active, productive, and stereoselective under mild reaction conditions for the ring-opening polymerization of lactide. The corresponding catalytic systems enable the production of stereoblock polymers with high molecular weights, allowing the formation of thermally stable and industrially relevant stereocomplexes.
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http://dx.doi.org/10.1002/anie.201903224DOI Listing
September 2019

Pyranopterin Related Dithiolene Molybdenum Complexes as Homogeneous Catalysts for CO Photoreduction.

Angew Chem Int Ed Engl 2018 12 28;57(52):17033-17037. Epub 2018 Nov 28.

Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS, Collège de France, Université Paris Sorbonne, 11 Place Marcelin Berthelot, 75231, Paris Cedex 05, France.

Two original dithiolenes, with a pyrazine ring fused with a pyran ring carrying the dithiolene chelate, mimicking molybdopterin (MPT) present in the active site of formate dehydrogenases (FDHs), have been synthesized. The first one mimicks MPT in the dihydropyrazine form while the second mimicks MPT in the more biologically relevant tetrahydropyrazine form. Both have been structurally characterized as a ligand within a cobalt(cyclopentadienyl)(dithiolene) complex. The corresponding MoO(dithiolene) complexes have been also prepared and are reported as the first functional and stable catalysts inspired by the Mo center of FDHs so far: they indeed catalyze the photoreduction of CO into formic acid, as the major product, and carbon monoxide, achieving more than 100 turnover numbers in about 8 h.
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http://dx.doi.org/10.1002/anie.201809084DOI Listing
December 2018

Thermally-Induced Spin Crossover and LIESST Effect in the Neutral [Fe(bik)(NCX)] Complexes: Variable-Temperature Structural, Magnetic, and Optical Studies (X = S, Se; bik = bis(1-methylimidazol-2-yl)ketone).

Front Chem 2018 21;6:326. Epub 2018 Aug 21.

Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, Paris, France.

Two new iron(II) neutral complexes of bis(1-methylimidazol-2-yl)ketone (bik) with molecular formula [Fe(bik)(NCS)] () and [Fe(bik)(NCSe)] () have been synthesized and characterized by magnetic measurements, single-crystal X-ray diffraction, and solid state UV-vis spectroscopy. The temperature dependent magnetic susceptibility measurements of crystalline samples of both compound show the occurrence of a gradual spin transition centered at = 260 K and 326 K, respectively. The crystal structures of both compounds were determined at different temperatures, below and above the transition, in order to detect the structural changes associated with the spin transition. The main structural modifications, when passing from the low-spin to the high-spin form, consist of an important lengthening of the Fe-N(Mebik) and Fe-N (C-S/Se) distances (by ca. 0.20 and 0.18 Å, respectively) and a noticeable variation of the N-Fe-N angles, leading to a more distorted [Fe-N6] octahedron. The spin-transition phenomenon also affects the optical properties, with significant decrease of the intensity of the Metal-to-Ligand charge transfer band upon increasing the temperature. Finally, both complexes exhibit a light-induced excited spin-state trapping under laser light irradiation at low temperature. DFT calculations were also carried out on these complexes in order to rationalize the theoretically predicted magnetic and optical behavior with those of the experimental one. The results clearly highlights the dramatic alteration of the magneto-structural behavior of the tris-chelate spin-crossover complex upon substituting one Mebik with NCS and NCSe ligands.
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http://dx.doi.org/10.3389/fchem.2018.00326DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6111792PMC
August 2018

A [Fe(Tp)(CN)] scorpionate-based complex as a building block for designing ion storage hosts (Tp: hydrotrispyrazolylborate).

Chem Commun (Camb) 2018 May;54(41):5189-5192

Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, IPCM, 4 place Jussieu, 75252 Paris, France.

Using a scorpionate-based complex, [FeIII(Tp)(CN)3]-, as a building block, a new cyanide-based molecular material [{FeIII(Tp)(CN)3}2NiII(H2O)2]·4H2O (1), which can be viewed as a lower dimensional model of Prussian blue analogues, was investigated as a lithium-ion storage host.
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http://dx.doi.org/10.1039/c8cc01374hDOI Listing
May 2018

Six States Switching of Redox-Active Molecular Tweezers by Three Orthogonal Stimuli.

J Am Chem Soc 2017 07 27;139(27):9213-9220. Epub 2017 Jun 27.

Sorbonne Universités, UPMC Univ Paris 06, CNRS, Institut Parisien de Chimie Moléculaire , UMR 8232, 4 place Jussieu, 75005 Paris, France.

A six level molecular switch based on terpyridine(Ni-salphen) tweezers and addressable by three orthogonal stimuli (metal coordination, redox reaction, and guest binding) is reported. By a metal coordination stimulus, the tweezers can be mechanically switched from an open "W"-shaped conformation to a closed "U"-shaped form. Theses two states can each be reversibly oxidized by the redox stimulus and bind to a pyrazine guest resulting in four additional states. All six states are stable and accessible by the right combination of stimuli and were studied by NMR, XRD, EPR spectroscopy, and DFT calculations. The combination of the supramolecular concepts of mechanical motion and guest binding with the redox noninnocent and valence tautomerism properties of Ni-salphen complexes added two new dimensions to a mechanical switch.
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http://dx.doi.org/10.1021/jacs.7b02945DOI Listing
July 2017

Photochemical studies on bis-sulfide and -sulfone tethered polyenic derivatives.

Org Biomol Chem 2017 May;15(19):4180-4190

Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 8232 Institut Parisien de Chimie Moléculaire, 4 place Jussieu, 75252 Paris cedex 05, France.

This study focusses on the [2 + 2]-photocycloaddition of a symmetric polyenic system tethered by an aryl bis-sulfide or sulfone platform. Using direct irradiation or photosensitization, no expected ladderane product was isolated. In most cases, only tricyclic products including a single cyclobutane moiety were formed. Irradiation of bis-acrylic precursors in water with encapsulation by a host (cyclodextrin or cucurbituril) provided a stereoselective access to valuable cyclobutyl adducts.
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http://dx.doi.org/10.1039/c7ob00551bDOI Listing
May 2017

Synthesis, Characterization, and DFT Analysis of Bis-Terpyridyl-Based Molecular Cobalt Complexes.

Inorg Chem 2017 May 25;56(10):5930-5940. Epub 2017 Apr 25.

Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS, Collège de France, Université Paris 6 , 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France.

Terpyridine ligands are widely used in chemistry and material sciences owing to their ability to form stable molecular complexes with a large variety of metal ions. In that context, variations of the substituents on the terpyridine ligand allow modulation of the material properties. Applying the Stille cross-coupling reaction, we prepared with good yields a new series of terpyridine ligands possessing quinoline-type moieties in ortho, meta, and para positions and dimethylamino substituents at central or distal positions. The corresponding cobalt(II) complexes were synthesized and fully characterized by elemental analysis, single-crystal X-ray crystallography, mass spectrometry, and UV-vis, H NMR, and Fourier transform infrared (FT-IR) spectroscopy as well as by cyclic voltammetry (CV). Density functional theory (DFT) calculations were performed to investigate the electronic structure of all the Co(II) bis-terpyridyl molecular complexes. In this work, we show that terpyridine ligand functionalization allows tuning the redox potentials of the Co(III)/Co(II), Co(II)/Co(I), and Co(I)/Co(I) (tpy) couples over a 1 V range.
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http://dx.doi.org/10.1021/acs.inorgchem.7b00595DOI Listing
May 2017

The unusual ring scission of a quinoxaline-pyran-fused dithiolene system related to molybdopterin.

Dalton Trans 2017 Mar;46(13):4161-4164

Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS, Collège de France, UPMC Université Paris 6, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France.

The reduction of the dithiolene ligand, qpdt, a mimic of the biological molybdopterin cofactor, and the corresponding (η-cyclopentadienyl)cobalt(iii) complex [(qpdt)CoCp] was studied. It was found that in both cases an unprecedented ring scission reaction took place in acidic medium. All new reaction products have been spectroscopically and structurally characterized. Plausible mechanisms for the formation of these products were also proposed.
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http://dx.doi.org/10.1039/c7dt00377cDOI Listing
March 2017

Luminescent Cyclometalated Platinum Complexes with π-Bonded Catecholate Organometallic Ligands.

Inorg Chem 2017 Feb 9;56(4):2050-2059. Epub 2017 Feb 9.

Sorbonne Universités, UPMC Universités Paris 06, and CNRS, IPCM, UMR 8232 , 4 place Jussieu, 75252 Paris Cedex 05, France.

A series of cyclometalated platinum(II) complexes of the type [(ppy)Pt(L)] (n = 0, 1) with π-bonded catecholates acting as organometallic ligands (L) have been prepared and characterized by analytical techniques. In addition, the structures of two complexes of the series were determined by single-crystal X-ray diffraction. The packing shows the formation of a 1D supramolecular assembly generated by d-π interactions among individual units. All complexes are luminescent in the solid state and in solution media. The results of photophysics have been rationalized by means of density functional theory (DFT) and time-dependent DFT investigations.
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http://dx.doi.org/10.1021/acs.inorgchem.6b02731DOI Listing
February 2017

New N^C^N-coordinated Pd(ii) and Pt(ii) complexes of a tridentate N-heterocyclic carbene ligand featuring a 6-membered central ring: synthesis, structures and luminescence.

Dalton Trans 2016 Aug;45(32):12644-8

Department of Chemistry, Durham University, Durham, DH1 3LE, U.K.

We describe Pd(ii) and Pt(ii) complexes of an N^C^N-coordinating pincer-like ligand featuring two lateral pyridine rings and a 6-membered carbene core. Their crystal structures display 1-dimensional chains with short π-π and M(ii)M(ii) interactions. Such interactions also impact on the photophysical properties, with the Pt(ii) complex being luminescent in the solid state at room temperature.
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http://dx.doi.org/10.1039/c6dt02415gDOI Listing
August 2016

A cobalt complex with a bioinspired molybdopterin-like ligand: a catalyst for hydrogen evolution.

Dalton Trans 2016 Oct 18;45(37):14754-63. Epub 2016 Jul 18.

Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS, Collège de France, Université Paris 6, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France.

Cobalt dithiolene complexes are a new class of H2-evolving catalysts. Here we describe the preparation, the structure and the catalytic activity of an original cobalt complex using a bioinspired ligand, a quinoxaline-pyran-fused dithiolene derivative (qpdt(2-)) that mimics the molybdopterin cofactor present in the active sites of formate dehydrogenases. This complex displays very good activity for electrochemical proton reduction under weak acid conditions in terms of turnover frequency, faradic yields and stability. Density functional theory calculations show that protonation of a nitrogen atom of the ligand decreases overpotentials by 520 mV and H2 formation proceeds via protonation of an intermediate Co-H hydride, with an adjacent S atom of the dithiolene ligand serving as a proton relay.
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http://dx.doi.org/10.1039/c6dt01824fDOI Listing
October 2016

Synthesis and Reactivity of a Bio-inspired Dithiolene Ligand and its Mo Oxo Complex.

Chemistry 2016 Mar 16;22(13):4447-53. Epub 2016 Feb 16.

Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS, Collège de France, Université Paris 6, 11 Place Marcelin Berthelot, 75231, Paris CEDEX 05, France.

An original synthesis of the fused pyranoquinoxaline dithiolene ligand qpdt(2-) is discussed in detail. The most intriguing step is the introduction of the dithiolene moiety by Pd-catalyzed carbon-sulfur coupling. The corresponding Mo(IV)O complex (Bu4N)2 [MoO(qpdt)2] (2) underwent reversible protonation in a strongly acidic medium and remained stable under anaerobic conditions. Besides, 2 was found to be very sensitive towards oxygen, as upon oxidation it formed a planar dithiin derivative. Moreover, the qpdt(2-) ligand in the presence of [MoCl4 (tBuNC)2] formed a tetracyclic structure. The products resulting from the unique reactivity of qpdt(2-) were characterized by X-ray diffraction, mass spectrometry, NMR spectroscopy, UV/Vis spectroscopy, and electrochemistry. Plausible mechanisms for the formation of these products are also proposed.
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http://dx.doi.org/10.1002/chem.201504373DOI Listing
March 2016

Induced phosphorescence from Pt → Ag and Ag(i)...Ag(i) metallophilic interactions in benzenedithiolatodiimine-Pt2/Ag2 clusters: a combined experimental and theoretical investigation.

Dalton Trans 2016 Feb 11;45(7):2906-13. Epub 2016 Jan 11.

Sorbonne Universités, UPMC Univ Paris 06, Université Pierre et Marie Curie, Institut Parisien de Chimie Moléculaire (IPCM) UMR 8232, 4 place Jussieu, 75252 Paris Cedex 05, France.

We report the synthesis and luminescence properties of a novel platinum(ii)-silver(i) cluster exhibiting supramolecular donor-acceptor dative Pt → Ag bonds as well as d(10)...d(10) argentophilic interactions. This compound was obtained by a self-assembly process upon mixing silver triflate with the [Pt(bdt)(bpy)] (1) building block. The new compound was characterized by infrared, NMR ((1)H, (13)C) and UV-vis spectroscopy. In addition, the molecular structure was unequivocally ascertained by a single-crystal X-ray diffraction study and shows that the assembly is identified as [(Pt2Ag2(o-bdt)2(bpy)2](CF3SO3)2 (2). Remarkably, the structure shows that complex 2 exists as two isomers I and II displaying different types of argentophilic interactions Ag...Ag as well as Pt → Ag dative bonds. These interactions are highly important and turn on phosphorescent emissions at low temperature depending on the nature of the isomer. The photophysical properties of both isomers were investigated and rationalized through TD-DFT calculations. This work paves the way to the synthesis of novel supramolecular assemblies displaying peculiar properties imparted from metallophilic as well as donor-acceptor metal-metal interactions.
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http://dx.doi.org/10.1039/c5dt03702fDOI Listing
February 2016

A Bioinspired Molybdenum Complex as a Catalyst for the Photo- and Electroreduction of Protons.

Angew Chem Int Ed Engl 2015 Nov 25;54(47):14090-3. Epub 2015 Sep 25.

Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS, Collège de France, Université Paris 6, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05 (France).

A molybdenum-dithiolene-oxo complex was prepared as a model of some active sites of Mo/W-dependent enzymes. The ligand, a quinoxaline-pyran-fused dithiolene, mimics molybdopterin present in these active sites. For the first time, this type of complex was shown to be active as a catalyst for the photoreduction of protons with excellent turnover numbers (500) and good stability in aqueous/organic media and for the electroreduction of protons in acetonitrile with remarkable rate constants (1030 s(-1) at -1.3 V versus Ag/AgCl). DFT calculations provided insight into the catalytic cycle of the reaction, suggesting that the oxo ligand plays a key role in proton exchange. These results provide a basis to optimize this new class of H2 -evolving catalysts.
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http://dx.doi.org/10.1002/anie.201505607DOI Listing
November 2015

Silicates as Latent Alkyl Radical Precursors: Visible-Light Photocatalytic Oxidation of Hypervalent Bis-Catecholato Silicon Compounds.

Angew Chem Int Ed Engl 2015 Sep 24;54(39):11414-8. Epub 2015 Jul 24.

Institut Parisien de Chimie Moléculaire, UMR CNRS 8232, Sorbonne Universités UPMC Univ Paris 06, 4 Place Jussieu, CC 229, 75252 Paris Cedex 05 (France).

This works introduces hypervalent bis-catecholato silicon compounds as versatile sources of alkyl radicals upon visible-light photocatalysis. Using Ir[(dF(CF3)ppy)2(bpy)](PF6) (dF(CF3)ppy = 2-(2,4-difluorophenyl)-5-trifluoromethylpyridine, bpy = bipyridine) as catalytic photooxidant, a series of alkyl radicals, including highly reactive primary ones can be generated and engaged in various intermolecular homolytic reactions. Based on cyclic voltammetry, Stern-Volmer studies, and supported by calculations, a mechanism involving a single-electron transfer from the silicate to the photoactivated iridium complex has been proposed. This oxidative photocatalyzed process can be efficiently merged with nickel-catalyzed Csp2-Csp3 cross-coupling reactions.
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http://dx.doi.org/10.1002/anie.201504963DOI Listing
September 2015

Mechanical switching of magnetic interaction by tweezers-type complex.

Chem Commun (Camb) 2015 Aug;51(65):12916-9

Sorbonne Universités, UPMC Univ Paris 06, UMR 8232, Institut Parisien de Chimie Moléculaire, 4 place Jussieu, 75005, Paris, France.

A control of the interaction between two spin centers was achieved by using a mechanical motion in a terpy(Cu-salphen)2 complex. Upon coordination a conformation change and switching from a paramagnetic to an antiferromagnetically coupled system was observed by EPR and SQUID measurements.
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http://dx.doi.org/10.1039/c5cc04980fDOI Listing
August 2015

Versatile access to Martin's spirosilanes and their hypervalent derivatives.

J Org Chem 2015 Mar 4;80(6):3280-8. Epub 2015 Mar 4.

‡Sorbonne Universités UPMC Universite Paris 06, UMR CNRS 8232, Institut Parisien de Chimie Moléculaire, 4 place Jussieu, CC 229, F-75005 Paris, France.

A new route to Martin's spirosilanes has been devised. The original synthesis does not allow diversely substituted spirosilane derivatives to be synthesized, and thus their corresponding silicates. In this report, Martin's spirosilanes bearing alkyl, aryl, halogen, alkoxy, and trifluoromethyl substituents on the aryl ring have been prepared through a versatile four-step route. Addition of fluoride onto these Lewis acids as a prototypical reaction with a nucleophile yielded a library of stable fluorosilicates. Both sets of compounds have been characterized by X-ray crystallography.
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http://dx.doi.org/10.1021/jo5028497DOI Listing
March 2015

Switchable platinum-based tweezers with Pt-Pt bonding and selective luminescence quenching.

Dalton Trans 2015 May;44(18):8543-51

Sorbonne Universités, UPMC Univ Paris 06, UMR 8232, Institut Parisien de Chimie Moléculaire, 4 place Jussieu, 75005, Paris, France.

Molecular tweezers incorporating peripheral platinum salphen complexes and a central chelating terpyridine group have been synthesized. The terpyridine can be switched upon metal binding between a free 'W' shaped form and a coordinated 'U' form. The crystallographic structure of the zinc-closed molecular tweezers was obtained and presented a strong π-stacking between the Pt-salphen units associated with a Pt-Pt bond. The luminescence properties, notably in response to selected guest ions (Zn(2+), Pb(2+), Hg(2+)) and the resulting mechanical motion, have been investigated by UV-Vis and emission spectroscopy. While ion coordination to the terpy resulted in no significant changes in the luminescence, a selective intercalation of a second Hg(2+) associated with a large differential quenching was observed.
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http://dx.doi.org/10.1039/c4dt03230fDOI Listing
May 2015

Synthesis, structure and magnetic properties of phenylhydroxamate-based coordination clusters.

Dalton Trans 2014 Nov;43(44):16805-17

Sorbonne Universités, UPMC Univ Paris 06, UMR 8232, Institut Parisien de Chimie Moléculaire, F-75005 Paris, France.

The strategic recombination of preformed coordination clusters in the presence of polymodal bridging ligands has successfully led to the characterisation of five new compounds of structural and magnetic interest. Indeed using the dinuclear complex [M2(H2O)(piv)4(Hpiv)4] (M = Co, Ni; Hpiv = pivalic acid) as starting material and reacting it with phenylhydroxamic acid (H2pha) has yielded the four tetrametallic coordination clusters [Co4(Hpha)2(piv)6(Hpiv)4] (1), [Ni4(Hpha)2(piv)6(Hpiv)2(DMF)2] (2), [Co4(Hpha)2(piv)6(EtOH)2(H2O)2] (3), [Ni4(Hpha)2(piv)6(EtOH)2(H2O)2] (4) and the hexanuclear complex [Co6(Hpha)4(piv)8(EtOH)2]·EtOH (5). All the compounds have been structurally characterised revealing a particular binding mode for the hydroxamate ligand. The study of their magnetic properties has been performed and the modelling of these properties has been done using the appropriate hamiltonians for each compound. The experimental data and their modelling show non-zero spin ground states for compounds 4 and 5.
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http://dx.doi.org/10.1039/c4dt02405bDOI Listing
November 2014

Tuning excited states of bipyridyl platinum(II) chromophores with π-bonded catecholate organometallic ligands: synthesis, structures, TD-DFT calculations, and photophysical properties.

Inorg Chem 2014 Jul 10;53(13):6624-33. Epub 2014 Jun 10.

Sorbonne Universités, UPMC Univ Paris 06, Université Pierre et Marie Curie and ‡CNRS, Centre National de la Recherche Scientifique, Institut Parisien de Chimie Moléculaire (IPCM) UMR 8232 , 4 place Jussieu, 75252 Paris cedex 05, France.

A series of bipyridyl (bpy) Pt(II) complexes with π-bonded catecholate (cat) [(bpy)Pt(LM)][BF4]n (2-5) (LM = Cp*Rh(cat), n = 2; Cp*Ir(cat), n = 2; Cp*Ru(cat), n = 1; and (C6H6)Ru(cat), n = 2) were prepared and fully characterized. The molecular structures of the four compounds were determined and showed that the solid-state packing is different and dependent on the π-bonded catecholate unit. For instance, while the (bpy)Pt(II) complexes 2 and 3 with rhodium and iridium catecholates did not show any Pt···Pt interactions those with the ruthenium catecholates 4 and 5 showed the presence of Pt···Pt and π-π interactions among individual units and generated one- and two-dimensional supramolecular chains. The photophysical properties of these compounds 2-5 were investigated and showed that all compounds are luminescent at low temperature, in contrast to the well-known parent compound [(C6H4O2)Pt(bpy)] (1), which is weakly luminescent at 77 K. Time-dependent density functional theory studies are advanced to explain this difference in behavior and to highlight the role of the π-bonded catecholate system.
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http://dx.doi.org/10.1021/ic500232wDOI Listing
July 2014

Solid-state hierarchical cyclodextrin-based supramolecular polymer constructed by primary, secondary, and tertiary azido interactions.

Angew Chem Int Ed Engl 2014 Jul 27;53(28):7238-42. Epub 2014 May 27.

Sorbonne Universités, UPMC Univ Paris 06, Institut Universitaire de France, Institut Parisien de Chimie Moléculaire (UMR CNRS 8232), 4, place Jussieu, 75005 Paris (France) http://www.ipcm.fr; CNRS, Institut Parisien de Chimie Moléculaire (UMR 8232), 4, place Jussieu, 75005 Paris (France).

The crystallization of a di-azido-α-cyclodextrin revealed a polymeric self-assembly involving a variety of azido-type interactions. The crystal arrangement relies on the cooperativity of a primary azido inclusion, a secondary azido-azido interaction involving an unprecedented distribution of canonical forms, and a tertiary azido-groove interaction. The second azido group brings in a major contribution to the supramolecular structure illustrating the benefit of a difunctionalization for the generation of hierarchy.
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http://dx.doi.org/10.1002/anie.201403578DOI Listing
July 2014