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Toulouse, France

Van Honschoten J.W.,University of Twente | Berenschot J.W.,University of Twente | Ondaruhu T.,NanoSciences Group | Sanders R.G.P.,University of Twente | And 3 more authors.
Applied Physics Letters | Year: 2010

We describe the fabrication of three-dimensional microstructures by means of capillary forces. Using an origami-like technique, planar silicon nitride structures of various geometries are folded to produce three-dimensional objects of 50-100 μm. Capillarity is a particularly effective mechanism since surface tension forces dominate over bulk forces at small scales. The spontaneous evaporation of water forms the driving mechanism for this microfabrication technique. Therefore the actuating liquid disappears in the final structure. A model describing the elastocapillary interaction of the folding process is compared with experiments. By tailoring the elastic and capillary properties a variety of three-dimensional micro-objects can be realized. © 2010 American Institute of Physics. Source

Fabie L.,NanoSciences Group | Fabie L.,Toulouse 1 University Capitole | Agostini P.,INSA Toulouse | Stopel M.,MESA Institute for Nanotechnology | And 5 more authors.
Nanoscale | Year: 2015

We report on the localized deposition of nanoparticles and proteins, nano-objects commonly used in many nanodevices, by the liquid nanodispensing (NADIS) technique which consists in depositing droplets of a solution through a nanochannel drilled at the apex of an AFM tip. We demonstrate that the size of spots can be adjusted from microns down to sub-50 nm by tuning the channel diameter, independently of the chemical nature of the solute. In the case of nanoparticles, we demonstrated the ultimate limit of the method and showed that large arrays of single (or pairs of) nanoparticles can be reproducibly deposited. We further explored the possibility to deposit different visible fluorescent proteins using NADIS without loss of protein function. The intrinsic fluorescence of these proteins is characteristic of their structural integrity; the retention of fluorescence after NADIS deposition demonstrates that the proteins are intact and functional. This study demonstrates that NADIS can be a viable alternative to other scanning probe lithography techniques since it combines high resolution direct writing of nanoparticles or biomolecules with the versatility of liquid lithography techniques. This journal is © The Royal Society of Chemistry. Source

Jacquot De Rouville H.-P.,NanoSciences Group | Garbage R.,NanoSciences Group | Cook R.E.,NanoSciences Group | Pujol A.R.,NanoSciences Group | And 3 more authors.
Chemistry - A European Journal | Year: 2012

Two new nanovehicles that have extended aromatic platforms as the cargo zones have been obtained. Two strategies were considered for the formation of the perylene core from two naphthalene precursors. The first was based on a Scholl-type reaction involving an oxidant, and the second used a brominated derivative to perform a homocoupling reaction. The first strategy failed under diverse coupling conditions in the presence of several strong oxidants. Nevertheless, the use of CoF 3 in trifluoroacetic acid triggered a dimerization reaction between two ester groups of one molecule and the naphthalene unit of another, thereby surprisingly yielding a ten-membered carbon macrocycle. The second strategy encountered a lack of reactivity of the substrate under several homocoupling conditions. The dimerization was not easily performed but Ullmann-type conditions ultimately gave the expected product. The low yield and low solubility of the product encouraged us to modify our initial design. The synthesis of a new chassis that incorporated additional tert-butyl groups improved the solubility of the molecules and also prevented overcyclization of the aromatic platform by blocking these positions. Some p-phenylene spacers were also intercalated between the iodine and perylene centers to increase the reactivity of the halide towards coupling reactions. Two new chassis were obtained by Scholl-type oxidative coupling using FeCl 3 as the oxidant. The introduction of four triptycene wheels allowed the formation of the two corresponding nanovehicles. Deux nouveaux nanovéhicules ont été obtenus avec une plateforme polyaromatique pouvant servir de zone de chargement. Deux stratégies de synthèse ont été considérées pour la formation du noyau pérylène à partir de deux précurseurs naphtaléniques. La première a fait intervenir une réaction de type Scholl mettant en jeu un oxydant, tandis que la seconde a mis en œuvre un dérivé bromé afin de réaliser un homocouplage. La première stratégie a échoué malgré de nombreuses conditions de couplage testées. Néanmoins, les conditions utilisant CoF 3 dans l'acide trifluoroacétique ont abouti à une dimérisation entre deux fonctions esters d'une molécule et le noyau naphtalène d'une seconde, conduisant à la formation d'un macrocycle à 10 chaënons. La seconde stratégie a également souffert d'un manque de réactivité du substrat lors de l'homocouplage. La dimérisation n'a pu s'effectuer facilement, mais les conditions de type Ullmann ont finalement permis d'aboutir au composé souhaité. Le faible rendement combiné à la faible solubilité du produit de cette réaction nous ont conduits à corriger le design initial. La synthèse d'un nouveau châssis a été entreprise en incorporant des groupements tert-butyles supplémentaires, afin d'améliorer la solubilité des molécules mais aussi pour éviter de surcycliser le châssis polyaromatique en bloquant ces positions. Des espaceurs p-phénylène ont également été intercalés entre l'atome d'iode et le noyau pérylène pour améliorer la réactivité de l'halogénure vis-à-vis des réactions de couplage. Deux nouveaux châssis ont ainsi été obtenus par couplage oxydant de type Scholl en utilisant FeCl 3 comme oxydant. L'introduction de quatre roues triptycènes a permis d'obtenir les deux nanovéhicules correspondants. En route! Two new molecular nanovehicles with a large dedicated cargo zone have been synthesized according to a modular strategy based on sequential double Knoevenagel and Diels-Alder reactions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Franc G.,NanoSciences Group | Franc G.,Toulouse 1 University Capitole | Gourdon A.,NanoSciences Group | Gourdon A.,Toulouse 1 University Capitole
Physical Chemistry Chemical Physics | Year: 2011

The fabrication of large molecular devices, directly on surfaces in UHV conditions, by covalent coupling of smaller precursors has become in the past years an attractive solution for Molecular Electronics. This review presents the state-of-the-art and an analysis of the potential of this new field, from Ullmann type C-C coupling, cyclodehydrogenation, and reactions involving heteroelements to 2D polymerisation on insulating thin films. Mechanistic insights are also mentioned, giving preliminary explanations on the influence of the substrate and the 2D confinement. Potential perspectives for further developments are then evoked. © the Owner Societies 2011. Source

Saywell A.,Fritz Haber Institute of the Max Planck Society | Gren W.,NanoSciences Group | Franc G.,NanoSciences Group | Gourdon A.,NanoSciences Group | And 3 more authors.
Journal of Physical Chemistry C | Year: 2014

The conformations of organometallic polymers formed via the bottom-up assembly of monomer units on a metal surface are investigated, and the relationship between the adsorption geometry of the individual monomer units, the conformational structure of the chain, and the overall shape of the polymer is explored. Iodine-functionalized monomer units deposited on a Au(111) substrate are found to form linear chain structures in which each monomer is linked to its neighbors via a Au adatom. Lateral manipulation of the linear chains using a scanning tunneling microscope allows the structure of the chain to be converted from a linear to a curved geometry, and it is shown that a transformation of the overall shape of the chain is coupled to a conformational rearrangement of the chain structure as well as a change in the adsorption geometry of the monomer units within the chain. The observed conformational structure of the curved chain is well-ordered and distinct from that of the linear chains. The structures of both the linear and curved chains are investigated by a combination of scanning tunneling microscopy measurements and theoretical calculations. © 2013 American Chemical Society. Source

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