Alain Chaumont

Alain Chaumont
University of Strasbourg | UNISTRA · UMR 7140 - Chimie de la Matière Complexe

PhD

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75
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1,775
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January 2016 - July 2017
University of Strasbourg
Position
  • Maître de Conférence

Publications

Publications (75)
Article
The design of smart nanocomposite supramolecular scaffolds for tissue engineering or anticancer applications, able to release drugs under external fields is currently a challenge. Such architectures require not only strong interactions between the polymer matrix and externally responsive nanomaterials, but also an efficient strategy for the loading...
Article
The formation of a tetranuclear self‐assembled species constructed around a TiO 4 N 2 motif is reported. This aggregate is generated from Ti(O i Pr) 4 , 2,2’‐bipyrimidine (bpym) and a bisbiphenol strand (L 2 H 4 ) where two 2,2’‐biphenol units are connected with a biphenyl spacer. The solid‐state structure of the [Ti 4 (L 2 ) 4 (bpym) 4 ] architect...
Article
The chemistry on octahedral TiO4N2‐complexes is described. The Ti(IV)‐based precursors are composed of two ligands 6,6’‐diphenyl‐2,2’‐biphenolato (1) and one substituted 1,10‐phenanthroline ligand (2‐5). The application of imine condensation, palladium‐catalyzed C‐C bond formation or copper‐catalysed azide‐alkyne cycloaddition allowed the grafting...
Article
Full-text available
Binary mixtures of hexafluoroisopropanol with either methanol or acetone are analyzed via classical molecular dynamics simulations and quantum cluster equilibrium calculations. In particular, their populations and thermodynamic properties are investigated with the binary quantum cluster equilibrium method, using our in‐house code \textsc{Peacemaker...
Article
Cold‐Spray Ionization mass spectrometry (CSI‐MS) that can be compared to an electrospray ionization (ESI) source acting with a nebulizing gas cooled by liquid nitrogen, is used for analysing reline as Deep Eutectic Solvent (DES). The association of cholinium chloride salts with urea molecules is evidenced in negative CSI‐MS through the chloride add...
Article
A bis‐acridinium cyclophane incorporating switchable acridinium moieties linked by a 3,5‐dipyridylanisole spacer was studied as a multi‐responsive host for polycyclic aromatic hydrocarbon guests. Complexation of perylene was proven to be the most effective and was characterized in particular by a charge transfer band as signal output. Effective cat...
Article
A bis‐acridinium cyclophane binds perylene selectively and reversibly upon chemical or redox stimuli in organic media. Its straightforward phase‐transfer into a perfluorocarbon was exploited for the enrichment of perylene from a mixture of polycyclic aromatic hydrocarbons (PAHs). Abstract A bis‐acridinium cyclophane incorporating switchable acridi...
Article
Tuning the dihedral angle (DA) of axially chiral compounds can impact biological activity, catalyst efficiency, molecular motor performance, or chiroptical properties. Herein, we report gradual, controlled and reversible changes in molecular conformation of a covalently linked binaphthyl moiety, within a 3D polymeric network by the application of a...
Article
Crosslinking BINOL derivatives in a 3D polymer network allows reversible tuning of the dihedral angle by macroscopic mechanical stretching of the material. This soft mechanotransduction was studied using simple and effective optical measurements of the host material and correlated with quantum molecular calculations and molecular dynamic simulation...
Article
Dipyrrolyldiketone ligands (dpkH) are used with Ti(OiPr)4 to afford monomeric titanium(IV) complexes displaying the general formula C2-[Ti(dpk)2(OiPr)2]. The dpkH ligands employed consist of two dipyrrolyldiketone compounds (2H and 3H) and three diphenyl-substituted analogues (4H-6H). The behavior of these octahedral [Ti(dpk)2(OiPr)2] species in so...
Article
A multicomponent self‐assembly reaction involving a bis‐biphenolato ligand (LH4), a 2,2'‐bipyrimidine chelate substituted by two (anthryl)vinyl moieties (bAnt) and Ti(OiPr)4 was investigated. An assembly {[Ti3(L)3(bAnt)3]}, composed of three homochiral TiO4N2 nodes, was characterized as being the thermodynamically‐end product. The crystal structure...
Article
The synthesis of monomeric octahedral complexes constructed around a TiO4N2 core bearing neocuproine derivatives is detailed. These architectures follow the [Ti(1)2(N-N)] general formulas, where 1 is the 6,6'-diphenyl-2,2'-biphenolato ligand and N-N is a 1,10-phenanthroline derivative. Single-crystal analysis revealed that the neocuproine-based lig...
Article
In recent years molecular dynamic simulations on Choline Chloride based Deep Eutectic Solvents (DES) have flourished. Most of these studies point to the fact that in order to accurately reproduce dynamical properties of the latter using a fixed-charge atomistic Force Fields (FF) one has to resort to charge scaling. In this work, we propose an alter...
Article
Full-text available
Autocatalysis and self‐assembly are key processes in developmental biology and are involved in the emergence of life. In the last decade both features were extensively investigated by chemists with the final goal to design synthetic living systems. Herein, we describe the autonomous growth of a self‐assembled soft material, i.e. a supramolecular hy...
Article
Towards emergence of life: A domino sequence of events starts from traces of an enzyme triggering peptide generation, which is followed by self‐assembly into catalytic nanofibers that can induce and amplify their own production over time. This self‐sustained cycle leads to an autocatalytic self‐assembled buildup of a hydrogel. Abstract Autocatalys...
Article
Thermoresponsive polymers, undergoing a reversible chemical or physical change using temperature as stimulus, attract increasing interest in particular as adaptable biomaterials. Except for zwitterionic polymers, fully charged polymers require the presence of specific ions to exhibit an upper critical solution temperature (UCST) in water. Herein, w...
Article
Inspired from biology, one current goal in supramolecular chemistry is to control the emergence of new functionalities arising from self‐assembly of molecules. In particular, some peptides can self‐assemble and lead to exceptional catalytically‐active fibrous networks able to underpin hydrogels. Unfortunately, the mechanical fragility of these mate...
Article
Inspired from biology, one current goal in supramolecular chemistry is to control the emergence of new functionalities arising from self‐assembly of molecules. In particular, some peptides can self‐assemble and lead to exceptional catalytically‐active fibrous networks able to underpin hydrogels. Unfortunately, the mechanical fragility of these mate...
Article
This article describes the formation of neutral TiO4N2-based coordination entities where the titanium centers are coordinated by oxygenated ligands incorporating one or two biphenolato units, i.e. L¹ and L² respectively. In these systems, the sixfold coordination spheres of each metallic center are completed by the enantiopure bidentate diphenyleth...
Article
To gain further insight into the internal motion of molecular objects, we have synthesized a molecular turnstile AzoT composed of a rotor based on flexible tetraethyleneglycol (TEG) chains grafted on aromatic moieties and a stator containing a photo‐switchable azobenzene (Azo) fragment. The control of the reversible light‐induced E‐AzoT Δ Z‐AzoT is...
Article
The oxidation of dopamine and of other catecholamines leads to the formation of conformal films on the surface of all known materials and to the formation of a precipitate in solution. In some cases, it has been shown that the addition of additives in the dopamine solution, like certain surfactants or polymers, polyelectrolytes and certain proteins...
Article
Localized self-assembly allowing both spatial and temporal control over the assembly process is essential in many biological systems. This can be achieved through localized enzyme-assisted self-assembly (LEASA), also called enzyme-instructed self-assembly, where enzymes present on a substrate catalyze a reaction that transforms non-interacting spec...
Article
The mechanism by which Zr-substituted and other transition metal-substituted polyoxometalates form covalently linked dimers has been analyzed by means of static density functional theory and Car−Parrinello molecular dynamics simulations. The study identifies the Zr-aqua-hydro anion, [W5O18Zr(OH)(H2O)]³⁻, as the active species under basic conditions...
Article
Full-text available
This manuscript describes the synthesis of a series of neutral titanium(iv) monomeric complexes constructed around a TiO4N2 core. The two nitrogen atoms that compose the coordination sphere of the metallic center belong to 2,2'-bipyrimidine ligands homo-disubstituted in the 4 and 4' positions by methyl (2a), phenylvinyl (2b), naphthylvinyl (2c) or...
Article
Purely organic radical ions dimerize in solution at low temperature, forming long, multicenter bonds, despite the metastability of the isolated dimers. Here, we present the first computational study of these π-dimers in solution, with explicit consideration of solvent molecules and finite temperature effects. By means of force-field and ab initio m...
Article
Full-text available
A series of deep-red colored nano-sized titanium oxo-clusters bearing catecholato ligands is reported. These architectures are produced via post-synthetic modification of the Ti10O12(cat)8(py)8 (cat = catecholato, py = pyridine) complex through quantitative substitution of labile pyridine ligands by three substituted pyridines (pico, 4-Phpy and pyr...
Article
Full-text available
The structural identification in solution of the Zr(iv) complexes involving two 2,2-biphenol-based proligands is reported. The proligand L(1)H2 contains one 2,2-biphenol unit whereas L(2)H4 incorporates two 2,2-biphenol units linked by a para-phenylene bridge. Diffusion Ordered Spectroscopy (DOSY) combined with electrospray mass spectrometry analys...
Article
We investigate the effect of stretching on the secondary structure of cross-linked poly(l-lysine)/hyaluronic acid (PLL/HA) multilayers. We show that stretching these films induces changes in the secondary structure of PLL chains. Our results suggest that not only α- but also 310-helices might form in the film under stretching. Such 310-helices have...
Article
Quantum chemical calculations are used to derive distributed polarizability models sufficiently accurate and compact to be used in classical Molecular Dynamics simulations of imidazolium-based room temperature ionic liquids. Two distributed polarizability models are fitted to reproduce the induction energy of three imidazolium cations (1,3-dimethyl...
Article
Static density functional theory (DFT) calculations with a continuous solvent model as well as classical and Car-Parrinello molecular dynamics (MD) simulations with explicit solvent molecules were performed to study the nature of Zr-monosubstituted monomeric and dimeric polyoxometalates (POMs) in water at different pHs. We have analyzed Zr-aqua, -h...
Article
We report molecular dynamics (MD) simulations of aqueous solutions of Keggin heteropolyacids XWn nH3O+ (XWn = [PW12O40]3, [SiW12O40]4, and [AlW12O40]5), the aim of which was to investigate whether the anions increasingly repulse each other in water when their charge increases from 3 to 5. The MD and PMF (potential of mean force) results indicate th...
Article
A multiscale computational study was performed with the aim of tracing the source of stereoselectivity and disclosing the role of water in the stereoselective step of propionaldehyde aldol self-condensation catalyzed by proline amide in water, a reaction that serves as a model for aqueous organocatalytic aldol condensations. Solvent mixing and hydr...
Article
Car-Parrinello molecular dynamics (CMPD) simulations and static computations are reported at the BLYP level of density functional theory (DFT) for mixed [LaCl(x)(H(2)O)(y)(MeCN)(z)](3-x) complexes in aqueous and nonaqueous solution (acetonitrile). Both methodologies predict coordination numbers (i.e., x + y + z) that are successively lower than nin...
Article
We report a molecular dynamics study on the EuBrn3-n complexes (n=0 to 6) formed upon complexation of Br- by Eu-3+ in the [BMI][PF6], [BMI][Tf2N] and [MeBu3N][Tf2N] ionic liquids (ILs), to compare the effect of the IL anion (PF6- versus Tf2N-), the IL cation (BMI+ versus MeBu3N+) and the IL humidity on their solvation and stability. In dry solution...
Article
The complexation of perrhenate (ReO(4)(-)) anions by the uranyl (UO(2)(2+)) cation has been investigated by joint molecular dynamics simulations and spectroscopic (UV-vis, TRLFS, and EXAFS) studies in aqueous solution, acetonitrile, and three ionic liquids (ILs), namely, [Bmi][Tf(2)N], [Me(3)BuN][Tf(2)N], and [Bu(3)MeN][Tf(2)N] that are based on th...
Article
Optimizations at the BLYP and B3LYP levels are reported for the mixed uranyl chloro/water/acetonitrile complexes [UO(2)Cl(n)(H(2)O)(x)(MeCN)(5-n-x)](2-n) (n = 1-3) and [UO(2)Cl(n)(H(2)O)(x)(MeCN)(4-n-x)](2-n) (n = 2-4), in both the gas phase and a polarizable continuum modeling acetonitrile. Car-Parrinello molecular dynamics (CPMD) simulations have...
Article
Optimizations at the BLYP and B3LYP levels are reported for mixed uranyl-water/acetonitrile complexes [UO(2)(H(2)O)(5-n)(MeCN)(n)](2+) (n = 0-5), in both the gas phase and a polarizable continuum modeling acetonitrile. Car-Parrinello molecular dynamics (CPMD) simulations have been performed for these complexes in the gas phase, and for selected spe...
Article
To investigate whether polyoxometallate α-PW12O403− Keggin anions (noted PW3−) repulse each other in water, we calculated the changes in free energy ΔG(d) as a function of the P…P distance d (potential of mean force “PMF” calculations). As the anions approach each other, the free energy profiles are found to be quite flat, with a tiny minimum at ca...
Article
In order to gain microscopic insights into the extraction mechanism of strontium cations by 18-crown-6 (18C6) to room temperature ionic liquids (ILs), we simulated by molecular dynamics (MD) strontium complexes in neat ionic liquids and at their interfaces with water. We compared two ILs, based on the PF(6)(-) anion and either 1-butyl-3-methylimida...
Article
By coupling EXAFS, UV-vis spectroscopy, and molecular dynamics and quantum mechanical calculations, we studied the competitive complexation of uranyl cations with nitrate and chloride ions in a water immiscible ionic liquid (IL), C(4)mimTf(2)N (C(4)mim(+): 1-butyl-3-methyl-imidazolium; Tf(2)N(-) = (CF(3)SO(2))(2)N)(-): bis(trifluoromethylsulfonyl)i...
Article
A recent computational study (Chaumont, A; Wipff, G. Phys. Chem. Chem. Phys. 2008, 10, 6940) showed that, in spite of their high charge and spherical shape, polyoxometalate α-PW12O403− Keggin anions PW3− can “attract each other” and form oligomers in water. This led us to speculate that these anions should also display surface-active properties, a...
Article
We report a molecular dynamics study of key species involved in the liquid-liquid extraction of the cesium picrate salt by an important extractant molecule L (the 1,3-alternate-dimethoxy-calix[4]arene-crown-6) at the chloroform-water interface, with the main aim being to investigate the effect of (i) the explicit representation of polarization effe...
Article
We report a molecular dynamics study on the solvation of trivalent lanthanide cations Ln((III)) (Ln = La, Eu and Yb) in the [BMI][SCN] and [MeBu(3)N][SCN] ionic liquids (ILs), based respectively on 1-methyl-3-butylimidazolium (BMI(+)) and tributylmethylammonium (MeBu(3)N(+)) cations, and on thiocyanate (SCN(-)) anions. For this purpose we first der...
Article
A prime number p is called elite if only finitely many Fermat numbers 22n + 1 are quadratic residues modulo p. So far, all 21 elite primes less than 250 billion were known, together with 24 larger items. We completed the systematic search up to the range of 2.5 · 1012 finding six more such numbers. Moreover, 42 new elites larger than this bound wer...
Article
Aqueous solutions of the polyoxometallate alpha-PW(12)O(40)(3-) Keggin anion "PW(3-)" have been simulated by molecular dynamics, comparing two anion concentrations (0.06 and ca. 0.15 mol l(-1)) and Cs(+), NBu(4)(+), UO(2)(2+), Eu(3+), H(3)O(+) and H(5)O(2)(+) as neutralizing M(n+) counterions. They reveal marked counterion effects of the degree of...
Article
The protein bacteriorhodopsin pumps protons across a bacterial membrane; its pumping cycle is triggered by the photoisomerization of a retinal cofactor and involves multiple proton-transfer reactions between intermittent protonation sites. These transfers are either direct or mediated by hydrogen-bonded networks, which may include internal water mo...
Article
The stepwise addition of 1 to 4 Cl(-) anions to the uranyl cation has been studied via potential of mean force (PMF) calculations in the [BMI][Tf 2N] ionic liquid based on the 1-butyl-3-methylimidazolium cation (BMI(+)) and the bis(trifluoromethylsulfonyl)imide anion (Tf2N(-)). According to these calculations, the four Cl(-) complexation reactions...
Article
The first coordination sphere of the uranyl cation in room-temperature ionic liquids (ILs) results from the competition between its initially bound counterions, the IL anions, and other anions (e.g., present as impurities or added to the solution). We present a joined spectroscopic (UV-visible and extended X-ray absorption fine structure)-simulatio...
Article
We report a molecular dynamics study of the solvation of spherical solutes Sq of ca. 5 Å radius in ionic liquids (ILs) based on the PF6− anion and the 1-butyl-3-methylimidazolium cation (BMI+) or 1-octyl-3-methylimidazolium cation (OMI+), as a function of the sign and magnitude of the charge q=0, ±1, ±2 and ±4 of Sq. The simulations highlight the d...
Article
Full-text available
A prime number p is called elite if only finitely many Fermat numbers 2^(2^n)+1 are quadratic residues of p. Previously only the interval up to 10^9 was systematically searched for elite primes and 16 such primes were found. We extended this research up to 2.5*10^11 and found five further elites, among which 1,151,139,841 is the smallest and 171,72...
Article
We report a molecular dynamics study of halide anions X− and their inclusion complexes X− ⊂ L4+ with a macrotricyclic tetrahedral host L4+ built from four quaternary ammonium sites, in an ionic liquid (IL) based on the 1-butyl-3-methylimidazolium (BMI+) cation and the PF6− anion. The “dry” and “humid” forms of the [BMI][PF6] IL are compared, showin...
Article
Full-text available
The solvation of the [UO(2)(NO(3))(CMPO)](+) and [UO(2)(NO(3))(2)(CMPO)(2)] complexes (CMPO = octyl(phenyl)-N,N-diisobutylmethylcarbamoyl phosphine oxide) is investigated by molecular dynamics in the "dry" and "humid" forms of a room temperature ionic liquid (IL) based on the 1-butyl-3-methylimidazolium (BMI(+)) cation and the hexafluorophosphate (...
Article
Combining spectroscopic techniques (TRES and EXAFS) and molecular dynamics simulations, we have investigated the state of trivalent europium dissolved in room-temperature ionic liquids (RTILs), as a function of the RTIL anion and in the presence of added chloride anions. The studied RTILs are based on the 1-butyl-3-methyl-imidazolium (Bumim+) catio...
Article
Density-functional-based Car-Parrinello molecular dynamics (CPMD) simulations have been performed for the ionic liquid 1,3-dimethylimidazolium chloride, [dmim]Cl, at 438 K. The local structure of the liquid is described in terms of various partial radial distribution functions and anisotropic spatial distributions, which reveal a significant extent...
Article
We report a molecular dynamics study of the interface between water and (macroscopically) water-immiscible room-temperature ionic liquids "ILs", composed of PF6(-) anions and butyl- versus octyl-substituted methylimidazolium+ cations (noted BMI+ and OMI+). Because the parameters used to simulate the pure ILs were found to exaggerate the water/IL mi...
Article
Full-text available
We report a molecular dynamics study on the solvation of EuFn(3-n) complexes in the [BMI][PF6] ionic liquid, composed of 1-butyl-3-methyl-imidazolium+ cations and PF6- anions. It is found that the most fluorinated complex in the liquid should be the EuF6(3-) species. In solution the EUF10(7-) and EuF7(4-) complexes indeed loose, respectively, 4 and...
Article
We report a molecular dynamics study of the solvation of 18-crown-6 (“18C6”) and of its K+, Cs+ and Sr2+ complexes in a room-temperature ionic liquid (IL) based on 1-butyl-3-methyl-imidazolium+, PF6−. “Dry” [BMI][PF6] versus “humid” [BMI][PF6][H2O] models of the IL are compared, demonstrating the importance of solvent humidity on the solvation prop...
Article
There have always been tight connections between supramolecular and theoretical chemistry. In the early seventies, quantum chemists introduced the "supermolecule" approach to analyze the strength and nature of the non-covalent interactions which assemble simple systems like the water dimer or water-ion adducts in the gas phase, and presumably large...
Article
We report a molecular dynamics study of the solvation of the UO2(2+) and Eu3+ cations and their chloro complexes in the [BMI][PF6][H2O] "humid" room-temperature ionic liquid (IL) composed of 1-butyl-3-methylimidazolium+ and PF6- ions and H2O in a 1:1:1 ratio. When compared to the results obtained in dry [BMI][PF6], the present results reveal the im...
Article
We report a molecular dynamics study of the solvation of UO2(2+), Eu3+ and Eu2+ ions in two "basic" (Lewis acidity) room-temperature ionic liquids (IL) composed of the 1-ethyl-3-methylimidazolium cation (EMI+) and a mixture of AlCl4- and Cl- anions, in which the Cl-/AlCl4- ratio is about 1 and 3, respectively. The study reveals the importance of th...
Article
The behavior of ion complexes at the water—supercritical carbon dioxide interface was considered by molecular dynamics simulations. The following complexes were studied: Cs+calix[4]crown-6, K+222 cryptate with chloride or dicarbollide (CCD–) counterions, the Sr2+18C6 complex with the picrate (Pic–) or perfluorooctanoate (PFO–) counterions, and the...
Article
The solvation of MCln3-n lanthanide chloride salts (La3+, Eu3+, and Yb3+; n = 3, 6, and 8) is studied by molecular dynamics simulations in two room-temperature ionic liquids which are “neutral” (Lewis acidity): [BMI][PF6] composed of 1-butyl-3-methyl-imidazolium+,PF6- ions and [EMI][TCA] composed of 1-ethyl-3-methyl-imidazolium+,AlCl4- ions. The si...
Article
Using molecular dynamics simulations, we compare the solvation of uranyl and strontium nitrates and uranyl chlorides in two room-temperature ionic liquids (ILs): [BMI][PF(6)] based on 1-butyl-3-methylimidazolium(+),PF(6)(-) and [EMI][TCA] based on 1-ethyl-3-methylimidazolium(+),AlCl(4)(-). Both dissociated M(2+),2NO(3)(-) and associated M(NO(3))(2)...
Article
We report a molecular dynamics study of the solvation of M3+ lanthanide cations (La3+, Eu3+ and Yb3+) in two room-temperature ionic liquids: [BMI][PF6] based on 1-butyl-3-methyl-imidazolium+,PF6− and [EMI][TCA] based on 1-ethyl-3-methyl-imidazolium+,AlCl4−. They reveal specific solvation as a function of the cation size and on the solvent. In [BMI]...
Article
We report a molecular dynamics study of the solvation of M3+ lanthanide cations (La3+, Eu3+ and Yb3+) in two room-temperature ionic liquids: [BMI][PF6] based on 1-butyl-3-methyl-imidazolium+,PF6− and [EMI][TCA] based on 1-ethyl-3-methyl-imidazolium+,AlCl4−. They reveal specific solvation as a function of the cation size and on the solvent. In [BMI]...
Article
According to molecular dynamics (MD) simulations the diprotonated bicyclic 222(2+) cryptand molecules concentrate on the water side of a water-chloroform interface. This is found for its endo-endo and exo-exo isomers and with Cl(-), I(-) or Pic(-) as counterions. The positively charged interfacial cryptands attract the halide anions which also conc...
Article
We report molecular dynamics potential of mean force (PMF) simulations on the capture of halide anions X(-) (F(-), Cl(-), Br(-)) by a tetrahedral receptor L(4+) built from four quaternary ammonium sites connected by six (CH(2))(n) chains, leading to the formation of inclusion complexes X(-) subset L(4+). Simulations performed with a reaction field...
Article
We report a molecular dynamics study of the halide inclusion complexes X(-) subset L(4+) of a macrotricyclic tetrahedral receptor L(4+) built from four quaternary ammonium sites connected by six (CH(2))(n) chains. The hydrophilic/hydrophobic character of the complexes is investigated at a water/chloroform interface, represented explicitly and, desp...
Article
dynamics (MD) simulations were performed with AMBER 7.0. The potential energy is described by a sum of bond, angle and dihedral deformations and pairwise additive 1-6-12 (electrostatic and van der Waals) interactions between nonbonded atoms: The IL solvent parameters are the same as in refs. [2] and [3]. The BMI + parameters are from Andrade et al....

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Project
Owing to the importance of titanium(IV)-based compounds in materials chemistry, the aim is to develop new versatile molecular precursors absorbing visible light. For anti-cancer drugs, the aim is to synthesize robust complexes towards hydrolysis, as a living cell is about 99 mol% water.