Bertrand Donnio - Academia.edu (original) (raw)
Papers by Bertrand Donnio
Journal of Materials Chemistry C
This study reports mesomorphic triphenylene-ethylammonium salts containing [MCl4]2− (M = Cu, Ni, ... more This study reports mesomorphic triphenylene-ethylammonium salts containing [MCl4]2− (M = Cu, Ni, Co, Mn) as counterion. The [NiCl4]2− group leads to combine mesomorphism, paramagnetism and thermochromism in the system.
Polymer Journal, Nov 9, 2016
The control of both the mesoscopic and nanoscale organizations within thin semiconducting films i... more The control of both the mesoscopic and nanoscale organizations within thin semiconducting films is a key issue for the improvement of the charge transport properties and the achievement of high charge-carrier mobilities. In this review, we summarized our previous work devoted to the design and synthesis of a new type of side-chain liquid crystal π-conjugated polymeric system associating regioregular poly(3-alkylthiophene) backbones with laterally pending π-conjugated mesogenic groups. Depending on the nature of the mesogenic side groups, this specific polymer design permits the production of lamellocolumnar or lamellolamellar mesophases, resulting in an intertwined co-assembly either of lamellae and columns or of two different types of lamellae. These optimized polymeric architectures based on two chemically different moieties constitute an interesting basis for the design of novel self-organized complex semiconducting materials. By associating with judicious side groups such as n-type entities, we demonstrated that this simple and versatile strategy can produce distinct conductive channels for both types of charge carrier and can lead to a new class of supramolecular ambipolar materials that is easily processable and potentially suitable for electronic and optoelectronic applications.
![Research paper thumbnail of Liquid-Crystalline [60]Fullerene-TTF Dyads](https://attachments.academia-assets.com/113367114/thumbnails/1.jpg)
](ChemInform, May 17, 2005
Compound 6. To a solution of 5 (580 mg, 1.356 mmol) in dry and degassed DMF (50 mL), was added a ... more Compound 6. To a solution of 5 (580 mg, 1.356 mmol) in dry and degassed DMF (50 mL), was added a solution of CsOH•H 2 O (273 mg, 1.627 mmol) in dry MeOH (2mL). The solution was stirred at room temperature for 30 min, and 6-bromo-1-hexanol (0.20 mL, 1.492 mmol) was added. The reaction mixture was stirred at room temperature for 7 h, and evaporated to dryness. The residue was dissolved in CH 2 Cl 2. The organic phase was washed (H 2 O), dried (MgSO 4), and evaporated to dryness. Purification of the residue by CC (silica gel; eluent: heptane/dichloromethane, 6:1, then increasing gradually the proportion of CH 2 Cl 2 , finally CH 2 Cl 2) gave pure 6 as an orange oil (500 mg, 80% yield). 1 H NMR (400 MHz, CD 2 Cl 2): δ 3.58
Journal of Physical Chemistry B, Dec 23, 2008
The formation of ferrimagnetic films of 39 nm magnetite nanoparticles functionalized by stilbene ... more The formation of ferrimagnetic films of 39 nm magnetite nanoparticles functionalized by stilbene derivatives has been studied using the Langmuir-Blodgett technique. The stilbene moieties are grafted to the particles either via a phosphonate or a carboxylate group; in both cases the nanoparticles display similar isotherms although the microscopic initial and final states of the films are different. Two different mechanisms of film formation are proposed, based on the inorganic-organic bond stability.
MRS Proceedings, 2007
ABSTRACTThere is currently a great interest in the preparation of nanostructured magnetic films p... more ABSTRACTThere is currently a great interest in the preparation of nanostructured magnetic films possessing well-defined structures and controlled properties. Recent progresses in colloidal nanocrystals synthesis and processing have led to new methods for producing films and superstructures made with these materials. Hybrid films have been prepared by organizing functionalized magnetite nanoparticles in large patterns using the Langmuir Blodgett technique. Magnetite nanoparticles with an average particle diameter of 39nm have been prepared and then coated with amphiphilic molecules. The resulting decorated particles, with a hydrophobic outer layer, have proven suitable for being processed by the LB technique. The microstructure and the compacity of the nanoparticle arrays appear to depend on the nature of the organic moiety used to decorate the nanoparticles (carboxylate or phosphonate end-capped stilbene derivatives).
Chemistry: A European Journal, Feb 12, 2007
... Emmanuel Terazzi Dr. 1 ,; Laure Guénée Dr. 1 ,; Pierre-Yves Morgantini Dr. 2 ,; Gérald Bernar... more ... Emmanuel Terazzi Dr. 1 ,; Laure Guénée Dr. 1 ,; Pierre-Yves Morgantini Dr. 2 ,; Gérald Bernardinelli Dr. 3 ,; Bertrand Donnio Dr. 4 ,; Daniel ... blocks induces significant changes in the aromatic polarizations as measured by the electrostatic potential calculated on the Connolly ...
Chemical Communications
Structurally related Zn(ii) and Cu(ii) metallomesogens based on phenanthroline and gallate chelat... more Structurally related Zn(ii) and Cu(ii) metallomesogens based on phenanthroline and gallate chelating units by chemical blending self-organize into a single Colhex mesophase, forming hetero-bimetallic liquid crystalline materials.
Nanomaterials
A metallomesogen based on an Zn(II) coordination complex was employed as precursor to obtain a co... more A metallomesogen based on an Zn(II) coordination complex was employed as precursor to obtain a complex matrix nanoplatform for the fabrication of a high-performance electrochemical hybrid sensor. Three representative paste electrodes, which differ by the weight ratio between Zn(II) metallomesogen and carbon nanotubes (CNT), i.e., PE_01, PE_02 and PE_03, were obtained by mixing the materials in different amounts. The composition with the largest amount of CNT with respect to Zn complex, i.e., PE_03, gives the best electrochemical signal for uric acid detection by cyclic voltammetry in an alkaline medium. The amphiphilic structure of the Zn(II) coordination complex likely induces a regular separation between the metal centers favoring the redox system through their reduction, followed by stripping, and is characterized by enhanced electrocatalytic activity towards uric acid oxidation. The comparative detection of uric acid between the PE_03 paste electrode and the commercial zinc elec...
Applied Sciences
The synthesis and structural characterization of a new liquid crystalline coordination complex ba... more The synthesis and structural characterization of a new liquid crystalline coordination complex based on pentacoordinated Zn(II) metal centre with the coordination fulfilled by the tridentate chelating N^N^N 2,2′;6′,2″-terpyridine ligand and two monoanionic gallates decorated with several long alkyl chains is described. The mesomorphic properties were accurately investigated by small- and wide-angle X-ray scattering studies. Despite the bulky coordination around the metal centre, the complex self-organizes into a smectic phase and, based on the structural and geometrical parameters, a model for the supramolecular organization in the liquid crystalline phase is proposed. Electrochemical investigations showed the importance of the molecular structure of the coordination complex in enhancing its aqueous sensing capacities: the bulky organic ligands form an organic shell separating the metal centres and favouring the redox system through their reduction followed by stripping.
A low temperature liquid crystal based on luminescent terpyridine Zn(II) complex is presented. Th... more A low temperature liquid crystal based on luminescent terpyridine Zn(II) complex is presented. The induction of the mesomorphic properties was achieved using a lipophilic gallate unit as ancillary ligands. The mesomorphic properties were investigated by polarised optical microscopy (POM), differential scanning calorimetry (DSC), thermogravimetric analysis (TA) and X-ray scattering (SWAXS) of bulk materials, while the optical properties of the complex were investigated in solution and in condensed liquid crystalline states.
A series of ionic tetracoordinated Pt(II) complexes based on terpyridine ligand were synthesized ... more A series of ionic tetracoordinated Pt(II) complexes based on terpyridine ligand were synthesized and characterized. Their chemical structures were engineered by using counterions of different coordination strengths and dimensions, namely non-coordinating BF4, weakly coordinating bulky gallate units, and small and strongly coordinating chlorine (Cl). The complexes containing lipophilic gallate units exhibit low temperature liquid crystalline properties. The mesomorphic properties were investigated by polarized optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction studies (SWAXS). Photophysical properties were determined in solution and condensed states.
European Journal of Inorganic Chemistry, 2021
We have studied the magnetic properties of various Boron particles obtained by different methods ... more We have studied the magnetic properties of various Boron particles obtained by different methods and have found evidence of soft ferromagnetism in all. While our study cannot unequivocally exclude that Boron is at the origin of the magnetism, we suggest that various impurities which are either the result of the synthetic process or come from the intentional doping of the Boron particles are indeed responsible for the observed magnetic properties. The phenomenon bears similarities with what is observed in magnetic oxides such as MgO or ZnO.
Dyes and Pigments, 2021
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
The Journal of Physical Chemistry C, 2021
Iron-oxide nanoparticles are intensively considered for high-performance biomedical applications,... more Iron-oxide nanoparticles are intensively considered for high-performance biomedical applications, where simultaneous functionalities, such as magnetic state, large surface area for maximal protein/enzyme binding, high magnetization values to provide large signals, and good dispersion in liquid media, are usually required. In this context, the association of individual nanoparticles into large clusters is of particular interest. Here, we present a magnetic force microscopy (MFM) approach capable to image individual nanoparticulate clusters as large as 350 nm at room temperature and under variable magnetic fields. It is shown that an in situ removal of electrostatic interactions─particularly important for large particle sizes supported by dielectric substrates─in MFM experiments based on phase detection allows us to image the magnetic state of individual clusters. After taking into account the magnetization behavior of the microscope tip, the phase signal reveals a gradual and uniform rotation of the magnetization with the magnetic field and the absence of a hysteretic behavior for all investigated clusters.
The Journal of Physical Chemistry C, 2020
Photoelectron excitations into unoccupied energy states are fundamental in solid-state physics an... more Photoelectron excitations into unoccupied energy states are fundamental in solid-state physics and many modern applications. The operation of such internal electronic transitions relies not only on photon absorption efficiency, which is pivotal in sensing, photovoltaics, active plasmonics, etc., but also on light-matter interactions and near/far-field spectroscopic techniques. Here, we report on a spectroscopic absorption fingerprint in magnetic circular dichroism (MCD) responses of various nanoparticulate systems. MCD spectra acquired at low temperatures on assemblies of uncoupled/coupled Ag and Au nanoparticles reveal asymmetric MCD spectral line shapes strongly depending on the nature and shape of nanoparticles and on their interparticular interactions. Assembling for instance the NPs into 2D networks with interparticle distances allowing dipolar interactions or transforming the spherical nanoparticles into disks was found to significantly alter the magneto-optic response in the spectral line shape. The findings are interpreted within the framework of chiral magneto-plasmonic effects by considering the k-dependent electronic states involved in both inter-and intraband electronic transitions. Additional Note : Our MCD spectra as a function of temperature (3-300 K) indeed indicate that a Cterm signal involving the splitting of the ground states is not important here.
![Research paper thumbnail of [4]Cyclo-N-alkyl-2,7-carbazoles: Influence of the Alkyl Chain Length on the Structural, Electronic, and Charge Transport Properties](https://attachments.academia-assets.com/113367141/thumbnails/1.jpg)
](Journal of the American Chemical Society, 2021
Macrocycles possessing radially oriented π−orbitals have experienced a fantastic development. How... more Macrocycles possessing radially oriented π−orbitals have experienced a fantastic development. However, their incorporation in organic electronic devices remains very scarce. In this work, we aim at bridging the gap between organic electronics and nanorings by reporting the first detailed structure-properties-device performance relationship study of organic functional materials based on a nanoring system. Three [4]cyclo-N-alkyl-2,7-carbazoles bearing different alkyl chains on their nitrogen atoms have been synthesized and characterized by combined experimental and theoretical approaches. This study includes electrochemical, photophysical, thermal and structural solid-state measurements and charge transport properties investigations. An optimized protocol of the Pt approach has been developed to synthesize the [4]-cyclocarbazoles in high yield (52-64%), of great interest for further development of nanorings especially in materials science. The charge transport properties of [4]-cyclocarbazoles and a model compound, [8]-cycloparaphenylene ([8]CPP), have been studied. Although no field effect (FE) mobility was recorded for benchmark [8]CPP, FE mobility values of ca 10-5 cm².V-1 .s-1 were recorded for the [4]-cyclocarbazoles. The characteristics (threshold voltage VTH, subthreshold swing SS, trapping energy ∆E) recorded for the three[4]-cyclocarbazoles appear to be modulated by the alkyl chain length borne by the nitrogen atoms. Remarkably, the space-charge-limited current mobilities measured for the [4]-cyclocarbazoles are about 3 orders of magnitude higher than that of [8]CPP (1.37/ 2.78×10-4 for the [4]-cyclocarbazoles vs 1.21×10-7 cm².V-1 .s-1 for [8]CPP) highlighting the strong effect of nitrogen bridges on the charge transport properties. The whole study opens the way to the use of nanorings in electronics, which is now the next step of their developments.
Physical Review Applied, 2019
We report on the near-field imaging of atomically thin layers of two-dimensional (2D) materials u... more We report on the near-field imaging of atomically thin layers of two-dimensional (2D) materials using photoinduced force mapping. This is accomplished by modifying a traditional atomic force microscopy setup to detect optical forces between a nanoscale tip and photoexcited sample. Our setup facilitates the imaging of few-layer flakes of MoS 2 or WS 2 and acquire optical force spectra, both in air and vacuum. The evaluated force spectra in both samples, exhibit the characteristic excitonic resonance peaks that are most typically observed in far-field absorption spectroscopy. We also show that nanoscale defect sites and flake edges can be distinguished from the crystalline flakes with high spectral resolution. Our results pave the way towards gaining a wholesome understanding of optical interactions and structure-property correlations in 2D materials and their heterostructures. Two-dimensional (2D) sheets of atomically thin Van der Waals-bonded crystals have recently opened up new avenues for studying light-matter interactions at the nanoscale. A wide array of candidates including graphene and a palette of transition metal dichalcagonides (TMDs), have fueled the tremendous surge of scientific interest in 2D materials, which demonstrate remarkable optoelectronic
Chemistry – A European Journal, 2020
Blue-green luminescent terpyridine-containing Pt II and Zn II complexes are reported. Equipped wi... more Blue-green luminescent terpyridine-containing Pt II and Zn II complexes are reported. Equipped with lipophilic gallate units, which act as monodentate ancillary coordinating ligands and/or as anions, they display low-temperature mesomorphic properties (lamello-columnar and hexagonal mesophases for Pt II and Zn II complexes, respectively). The mesomorphic properties were investigated by polarised optical microscopy, differential scanning calorimetry, thermogravimetric analysis and X-ray scattering of bulk materials and oriented thin films. The model of self-assembly into the lamello-columnar phase of the Pt II complex has been described in detail. The optical properties of the complexes were investigated in the liquid and condensed liquid crystalline states, highlighting the delicate balance between the role of the metal in determining the type of excited state responsible for the emission, and the role of the ancillary ligand in driving intermolecular interactions for proper mesophase formation. Pt_1 155 Dec [d] Pt_2 303 Cr 37.1 (-) [e,f] M+Colhex∼100-155 (-) Iso Iso 140.0 (-) [e,f] Iso+Colhex 84.9 (−8.5) M+Colhex 18.5 (−70.6) Cr Cr 39.2 (74.7) M+Colhex 89.3 (8.3) [f] Iso+Colhex 155 (-) Iso Pt_3 280 Cr 170 (-) [e] Iso Pt_4 285 LamColr 65-135 (11.6) [f] LamCol 255 (-) [e] Iso Zn_1 246 Cr 243 (-) [e] Iso Zn_2 309 Colhex 101 (2.2) Iso Iso 108 (−2.0) Colhex
Nanoscale, 2020
The usage of magnetic nanoparticles (NPs) in applications necessitates a precise mastering of the... more The usage of magnetic nanoparticles (NPs) in applications necessitates a precise mastering of their properties at the single nanoparticle level.
Nano Letters, 2020
In this article, we show how advanced hierarchical structures of topological defects in the so-ca... more In this article, we show how advanced hierarchical structures of topological defects in the so-called smectic oily streaks can be used to sequentially transfer their geometrical features to gold nanospheres. We use two kinds of topological defects, 1D dislocations and 2D ribbon-like topological defects. The large trapping efficiency of the smectic dislocation cores not only surpasses that of the elastically distorted zones around the cores but also the one of the 2D ribbon-like topological defect. This enables the formation of a large number of aligned NP chains, within the dislocation cores that can be quasi-fully filled without any significant aggregation outside the cores. When the NP concentration is large enough to entirely fill the dislocation cores, the LC confinement varies from 1D to 2D. We demonstrate that the 2D topological defect cores induce a confinement that leads to planar hexagonal networks of NPs. We then draw the phase diagram driven by NP concentration, associated with the sequential confinements induced by these two kinds of topological defects. Owing to the excellent large-scale order of these defect cores, not only the NP chains but also the NP hexagonal networks can be oriented along the desired direction, suggesting a possible new route for the creation of either 1D or 2D highly anisotropic NP networks. In addition, these results open rich perspectives based on the possible creation of coexisting NP assemblies of different kinds, localized in different confining areas of a same smectic film that would thus interact thanks to their proximity but also would interact via the surrounding soft matter matrix.
Journal of Materials Chemistry C
This study reports mesomorphic triphenylene-ethylammonium salts containing [MCl4]2− (M = Cu, Ni, ... more This study reports mesomorphic triphenylene-ethylammonium salts containing [MCl4]2− (M = Cu, Ni, Co, Mn) as counterion. The [NiCl4]2− group leads to combine mesomorphism, paramagnetism and thermochromism in the system.
Polymer Journal, Nov 9, 2016
The control of both the mesoscopic and nanoscale organizations within thin semiconducting films i... more The control of both the mesoscopic and nanoscale organizations within thin semiconducting films is a key issue for the improvement of the charge transport properties and the achievement of high charge-carrier mobilities. In this review, we summarized our previous work devoted to the design and synthesis of a new type of side-chain liquid crystal π-conjugated polymeric system associating regioregular poly(3-alkylthiophene) backbones with laterally pending π-conjugated mesogenic groups. Depending on the nature of the mesogenic side groups, this specific polymer design permits the production of lamellocolumnar or lamellolamellar mesophases, resulting in an intertwined co-assembly either of lamellae and columns or of two different types of lamellae. These optimized polymeric architectures based on two chemically different moieties constitute an interesting basis for the design of novel self-organized complex semiconducting materials. By associating with judicious side groups such as n-type entities, we demonstrated that this simple and versatile strategy can produce distinct conductive channels for both types of charge carrier and can lead to a new class of supramolecular ambipolar materials that is easily processable and potentially suitable for electronic and optoelectronic applications.
ChemInform, May 17, 2005
Compound 6. To a solution of 5 (580 mg, 1.356 mmol) in dry and degassed DMF (50 mL), was added a ... more Compound 6. To a solution of 5 (580 mg, 1.356 mmol) in dry and degassed DMF (50 mL), was added a solution of CsOH•H 2 O (273 mg, 1.627 mmol) in dry MeOH (2mL). The solution was stirred at room temperature for 30 min, and 6-bromo-1-hexanol (0.20 mL, 1.492 mmol) was added. The reaction mixture was stirred at room temperature for 7 h, and evaporated to dryness. The residue was dissolved in CH 2 Cl 2. The organic phase was washed (H 2 O), dried (MgSO 4), and evaporated to dryness. Purification of the residue by CC (silica gel; eluent: heptane/dichloromethane, 6:1, then increasing gradually the proportion of CH 2 Cl 2 , finally CH 2 Cl 2) gave pure 6 as an orange oil (500 mg, 80% yield). 1 H NMR (400 MHz, CD 2 Cl 2): δ 3.58
Journal of Physical Chemistry B, Dec 23, 2008
The formation of ferrimagnetic films of 39 nm magnetite nanoparticles functionalized by stilbene ... more The formation of ferrimagnetic films of 39 nm magnetite nanoparticles functionalized by stilbene derivatives has been studied using the Langmuir-Blodgett technique. The stilbene moieties are grafted to the particles either via a phosphonate or a carboxylate group; in both cases the nanoparticles display similar isotherms although the microscopic initial and final states of the films are different. Two different mechanisms of film formation are proposed, based on the inorganic-organic bond stability.
MRS Proceedings, 2007
ABSTRACTThere is currently a great interest in the preparation of nanostructured magnetic films p... more ABSTRACTThere is currently a great interest in the preparation of nanostructured magnetic films possessing well-defined structures and controlled properties. Recent progresses in colloidal nanocrystals synthesis and processing have led to new methods for producing films and superstructures made with these materials. Hybrid films have been prepared by organizing functionalized magnetite nanoparticles in large patterns using the Langmuir Blodgett technique. Magnetite nanoparticles with an average particle diameter of 39nm have been prepared and then coated with amphiphilic molecules. The resulting decorated particles, with a hydrophobic outer layer, have proven suitable for being processed by the LB technique. The microstructure and the compacity of the nanoparticle arrays appear to depend on the nature of the organic moiety used to decorate the nanoparticles (carboxylate or phosphonate end-capped stilbene derivatives).
Chemistry: A European Journal, Feb 12, 2007
... Emmanuel Terazzi Dr. 1 ,; Laure Guénée Dr. 1 ,; Pierre-Yves Morgantini Dr. 2 ,; Gérald Bernar... more ... Emmanuel Terazzi Dr. 1 ,; Laure Guénée Dr. 1 ,; Pierre-Yves Morgantini Dr. 2 ,; Gérald Bernardinelli Dr. 3 ,; Bertrand Donnio Dr. 4 ,; Daniel ... blocks induces significant changes in the aromatic polarizations as measured by the electrostatic potential calculated on the Connolly ...
Chemical Communications
Structurally related Zn(ii) and Cu(ii) metallomesogens based on phenanthroline and gallate chelat... more Structurally related Zn(ii) and Cu(ii) metallomesogens based on phenanthroline and gallate chelating units by chemical blending self-organize into a single Colhex mesophase, forming hetero-bimetallic liquid crystalline materials.
Nanomaterials
A metallomesogen based on an Zn(II) coordination complex was employed as precursor to obtain a co... more A metallomesogen based on an Zn(II) coordination complex was employed as precursor to obtain a complex matrix nanoplatform for the fabrication of a high-performance electrochemical hybrid sensor. Three representative paste electrodes, which differ by the weight ratio between Zn(II) metallomesogen and carbon nanotubes (CNT), i.e., PE_01, PE_02 and PE_03, were obtained by mixing the materials in different amounts. The composition with the largest amount of CNT with respect to Zn complex, i.e., PE_03, gives the best electrochemical signal for uric acid detection by cyclic voltammetry in an alkaline medium. The amphiphilic structure of the Zn(II) coordination complex likely induces a regular separation between the metal centers favoring the redox system through their reduction, followed by stripping, and is characterized by enhanced electrocatalytic activity towards uric acid oxidation. The comparative detection of uric acid between the PE_03 paste electrode and the commercial zinc elec...
Applied Sciences
The synthesis and structural characterization of a new liquid crystalline coordination complex ba... more The synthesis and structural characterization of a new liquid crystalline coordination complex based on pentacoordinated Zn(II) metal centre with the coordination fulfilled by the tridentate chelating N^N^N 2,2′;6′,2″-terpyridine ligand and two monoanionic gallates decorated with several long alkyl chains is described. The mesomorphic properties were accurately investigated by small- and wide-angle X-ray scattering studies. Despite the bulky coordination around the metal centre, the complex self-organizes into a smectic phase and, based on the structural and geometrical parameters, a model for the supramolecular organization in the liquid crystalline phase is proposed. Electrochemical investigations showed the importance of the molecular structure of the coordination complex in enhancing its aqueous sensing capacities: the bulky organic ligands form an organic shell separating the metal centres and favouring the redox system through their reduction followed by stripping.
A low temperature liquid crystal based on luminescent terpyridine Zn(II) complex is presented. Th... more A low temperature liquid crystal based on luminescent terpyridine Zn(II) complex is presented. The induction of the mesomorphic properties was achieved using a lipophilic gallate unit as ancillary ligands. The mesomorphic properties were investigated by polarised optical microscopy (POM), differential scanning calorimetry (DSC), thermogravimetric analysis (TA) and X-ray scattering (SWAXS) of bulk materials, while the optical properties of the complex were investigated in solution and in condensed liquid crystalline states.
A series of ionic tetracoordinated Pt(II) complexes based on terpyridine ligand were synthesized ... more A series of ionic tetracoordinated Pt(II) complexes based on terpyridine ligand were synthesized and characterized. Their chemical structures were engineered by using counterions of different coordination strengths and dimensions, namely non-coordinating BF4, weakly coordinating bulky gallate units, and small and strongly coordinating chlorine (Cl). The complexes containing lipophilic gallate units exhibit low temperature liquid crystalline properties. The mesomorphic properties were investigated by polarized optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction studies (SWAXS). Photophysical properties were determined in solution and condensed states.
European Journal of Inorganic Chemistry, 2021
We have studied the magnetic properties of various Boron particles obtained by different methods ... more We have studied the magnetic properties of various Boron particles obtained by different methods and have found evidence of soft ferromagnetism in all. While our study cannot unequivocally exclude that Boron is at the origin of the magnetism, we suggest that various impurities which are either the result of the synthetic process or come from the intentional doping of the Boron particles are indeed responsible for the observed magnetic properties. The phenomenon bears similarities with what is observed in magnetic oxides such as MgO or ZnO.
Dyes and Pigments, 2021
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
The Journal of Physical Chemistry C, 2021
Iron-oxide nanoparticles are intensively considered for high-performance biomedical applications,... more Iron-oxide nanoparticles are intensively considered for high-performance biomedical applications, where simultaneous functionalities, such as magnetic state, large surface area for maximal protein/enzyme binding, high magnetization values to provide large signals, and good dispersion in liquid media, are usually required. In this context, the association of individual nanoparticles into large clusters is of particular interest. Here, we present a magnetic force microscopy (MFM) approach capable to image individual nanoparticulate clusters as large as 350 nm at room temperature and under variable magnetic fields. It is shown that an in situ removal of electrostatic interactions─particularly important for large particle sizes supported by dielectric substrates─in MFM experiments based on phase detection allows us to image the magnetic state of individual clusters. After taking into account the magnetization behavior of the microscope tip, the phase signal reveals a gradual and uniform rotation of the magnetization with the magnetic field and the absence of a hysteretic behavior for all investigated clusters.
The Journal of Physical Chemistry C, 2020
Photoelectron excitations into unoccupied energy states are fundamental in solid-state physics an... more Photoelectron excitations into unoccupied energy states are fundamental in solid-state physics and many modern applications. The operation of such internal electronic transitions relies not only on photon absorption efficiency, which is pivotal in sensing, photovoltaics, active plasmonics, etc., but also on light-matter interactions and near/far-field spectroscopic techniques. Here, we report on a spectroscopic absorption fingerprint in magnetic circular dichroism (MCD) responses of various nanoparticulate systems. MCD spectra acquired at low temperatures on assemblies of uncoupled/coupled Ag and Au nanoparticles reveal asymmetric MCD spectral line shapes strongly depending on the nature and shape of nanoparticles and on their interparticular interactions. Assembling for instance the NPs into 2D networks with interparticle distances allowing dipolar interactions or transforming the spherical nanoparticles into disks was found to significantly alter the magneto-optic response in the spectral line shape. The findings are interpreted within the framework of chiral magneto-plasmonic effects by considering the k-dependent electronic states involved in both inter-and intraband electronic transitions. Additional Note : Our MCD spectra as a function of temperature (3-300 K) indeed indicate that a Cterm signal involving the splitting of the ground states is not important here.
Journal of the American Chemical Society, 2021
Macrocycles possessing radially oriented π−orbitals have experienced a fantastic development. How... more Macrocycles possessing radially oriented π−orbitals have experienced a fantastic development. However, their incorporation in organic electronic devices remains very scarce. In this work, we aim at bridging the gap between organic electronics and nanorings by reporting the first detailed structure-properties-device performance relationship study of organic functional materials based on a nanoring system. Three [4]cyclo-N-alkyl-2,7-carbazoles bearing different alkyl chains on their nitrogen atoms have been synthesized and characterized by combined experimental and theoretical approaches. This study includes electrochemical, photophysical, thermal and structural solid-state measurements and charge transport properties investigations. An optimized protocol of the Pt approach has been developed to synthesize the [4]-cyclocarbazoles in high yield (52-64%), of great interest for further development of nanorings especially in materials science. The charge transport properties of [4]-cyclocarbazoles and a model compound, [8]-cycloparaphenylene ([8]CPP), have been studied. Although no field effect (FE) mobility was recorded for benchmark [8]CPP, FE mobility values of ca 10-5 cm².V-1 .s-1 were recorded for the [4]-cyclocarbazoles. The characteristics (threshold voltage VTH, subthreshold swing SS, trapping energy ∆E) recorded for the three[4]-cyclocarbazoles appear to be modulated by the alkyl chain length borne by the nitrogen atoms. Remarkably, the space-charge-limited current mobilities measured for the [4]-cyclocarbazoles are about 3 orders of magnitude higher than that of [8]CPP (1.37/ 2.78×10-4 for the [4]-cyclocarbazoles vs 1.21×10-7 cm².V-1 .s-1 for [8]CPP) highlighting the strong effect of nitrogen bridges on the charge transport properties. The whole study opens the way to the use of nanorings in electronics, which is now the next step of their developments.
Physical Review Applied, 2019
We report on the near-field imaging of atomically thin layers of two-dimensional (2D) materials u... more We report on the near-field imaging of atomically thin layers of two-dimensional (2D) materials using photoinduced force mapping. This is accomplished by modifying a traditional atomic force microscopy setup to detect optical forces between a nanoscale tip and photoexcited sample. Our setup facilitates the imaging of few-layer flakes of MoS 2 or WS 2 and acquire optical force spectra, both in air and vacuum. The evaluated force spectra in both samples, exhibit the characteristic excitonic resonance peaks that are most typically observed in far-field absorption spectroscopy. We also show that nanoscale defect sites and flake edges can be distinguished from the crystalline flakes with high spectral resolution. Our results pave the way towards gaining a wholesome understanding of optical interactions and structure-property correlations in 2D materials and their heterostructures. Two-dimensional (2D) sheets of atomically thin Van der Waals-bonded crystals have recently opened up new avenues for studying light-matter interactions at the nanoscale. A wide array of candidates including graphene and a palette of transition metal dichalcagonides (TMDs), have fueled the tremendous surge of scientific interest in 2D materials, which demonstrate remarkable optoelectronic
Chemistry – A European Journal, 2020
Blue-green luminescent terpyridine-containing Pt II and Zn II complexes are reported. Equipped wi... more Blue-green luminescent terpyridine-containing Pt II and Zn II complexes are reported. Equipped with lipophilic gallate units, which act as monodentate ancillary coordinating ligands and/or as anions, they display low-temperature mesomorphic properties (lamello-columnar and hexagonal mesophases for Pt II and Zn II complexes, respectively). The mesomorphic properties were investigated by polarised optical microscopy, differential scanning calorimetry, thermogravimetric analysis and X-ray scattering of bulk materials and oriented thin films. The model of self-assembly into the lamello-columnar phase of the Pt II complex has been described in detail. The optical properties of the complexes were investigated in the liquid and condensed liquid crystalline states, highlighting the delicate balance between the role of the metal in determining the type of excited state responsible for the emission, and the role of the ancillary ligand in driving intermolecular interactions for proper mesophase formation. Pt_1 155 Dec [d] Pt_2 303 Cr 37.1 (-) [e,f] M+Colhex∼100-155 (-) Iso Iso 140.0 (-) [e,f] Iso+Colhex 84.9 (−8.5) M+Colhex 18.5 (−70.6) Cr Cr 39.2 (74.7) M+Colhex 89.3 (8.3) [f] Iso+Colhex 155 (-) Iso Pt_3 280 Cr 170 (-) [e] Iso Pt_4 285 LamColr 65-135 (11.6) [f] LamCol 255 (-) [e] Iso Zn_1 246 Cr 243 (-) [e] Iso Zn_2 309 Colhex 101 (2.2) Iso Iso 108 (−2.0) Colhex
Nanoscale, 2020
The usage of magnetic nanoparticles (NPs) in applications necessitates a precise mastering of the... more The usage of magnetic nanoparticles (NPs) in applications necessitates a precise mastering of their properties at the single nanoparticle level.
Nano Letters, 2020
In this article, we show how advanced hierarchical structures of topological defects in the so-ca... more In this article, we show how advanced hierarchical structures of topological defects in the so-called smectic oily streaks can be used to sequentially transfer their geometrical features to gold nanospheres. We use two kinds of topological defects, 1D dislocations and 2D ribbon-like topological defects. The large trapping efficiency of the smectic dislocation cores not only surpasses that of the elastically distorted zones around the cores but also the one of the 2D ribbon-like topological defect. This enables the formation of a large number of aligned NP chains, within the dislocation cores that can be quasi-fully filled without any significant aggregation outside the cores. When the NP concentration is large enough to entirely fill the dislocation cores, the LC confinement varies from 1D to 2D. We demonstrate that the 2D topological defect cores induce a confinement that leads to planar hexagonal networks of NPs. We then draw the phase diagram driven by NP concentration, associated with the sequential confinements induced by these two kinds of topological defects. Owing to the excellent large-scale order of these defect cores, not only the NP chains but also the NP hexagonal networks can be oriented along the desired direction, suggesting a possible new route for the creation of either 1D or 2D highly anisotropic NP networks. In addition, these results open rich perspectives based on the possible creation of coexisting NP assemblies of different kinds, localized in different confining areas of a same smectic film that would thus interact thanks to their proximity but also would interact via the surrounding soft matter matrix.