Synthesis and self-assembly properties of fulleropyrrolidine prepared by Prato reaction

International audienceMolecular self-assembly is considered as a promising way to control the manufacture of new materials and their integration into hybrid devices with novel properties. In this work we have synthesized a fulleropyrrolidine bearing a phenylacetylene moiety via the Prato reaction. The characterization of the fulleropyrrolidine by nuclear magnetic resonance and optical spectroscopy is reported, and its self-assembly by crystallization study has been investigated according to the used solvents. If the solvent that effectively solubilizes fullerene derivative is tetrahydrofurane, the nano-square plates with 1–3 μ m in length and 50–100 nm in thickness are formed, while if the solvent is toluene, 5 μ m diameter ‘nano-flowers’ are obtained

Cofactor-specific covalent anchoring of cytochrome b 562 on a single-walled carbon nanotube by click chemistry †

International audienceRedox-active cytochrome b 562 with a tethered azide group on the heme propionate side chain is covalently linked to an acetylene moiety introduced on the sidewall of a single-walled carbon nanotube (SWNT) by copper-catalyzed click chemistry forming a triazole ring with the heme active site directly linked to the SWNT. The cytochrome b 562 –SWNT hybrid is characterized by electrochemistry and atomic force microscopy. Interfacing redox-active enzymes with electrode materials is a key technology used in the development of high performance biosensors and biofuel cells. 1–3 Recent advances in carbon nanomaterials have enabled us to design hybrid systems with linked enzymes. Carbon nanotubes (CNTs), of the single-or multi-walled type, are promising building blocks for fabrication of hybrid materials. 4–8 CNTs have large surface areas, high strength, chemical stability, and attractive electronic properties. CNTs have also provided a wide variety of synthetic tools applicable for introduction of a range of substituents for linking the enzymes. A copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction is a widely utilized method used to form a covalent linkage which includes a triazole ring between building blocks containing azide and alkyne groups. 9,10 The CuAAC reaction has thus been used in organic synthesis, bio-conjugation chemistry, and surface chemistry. This powerful coupling reaction can be applied in efforts to efficiently tailor the chemical modication of single-walled CNTs (SWNTs) to construct hybrid materials 11–13 including enzymes. 14 Redox-active hemoproteins form a major class of enzymes that are useful for constructing enzyme-immobilized electrodes due to their diverse functions including electron transfer, catal-ysis, and sensing. 15–25 Many hemoproteins possess a replaceable heme b cofactor in the heme pocket, enabling immobilization on the electrode via the heme–heme pocket interaction. 26–45 In this paper, we demonstrate specically oriented covalent immobili-zation of azide-linked cytochrome b 562 (CYT) on the sidewall of SWNT using the CuAAC reaction (Fig. 1). The advantage of this method which uses a replaceable heme tethered to an azide moiety, lies in the wide range of applications for functionaliza-tion of wild-type hemoproteins. The characterization and elec-trochemical properties of the covalently-linked hybrid materials of SWNT and cytochrome b 562 are described. Fig. 1 (a) SWNT with covalently-linked cytochrome b 562 and (b) the preparation scheme using a copper-catalyzed azide–alkyne cyclo-addition (CuAAC) reaction

Recent Advances in Molecular Electronics Based on Carbon Nanotubes

Carbon nanotubes (CNTs) have exceptional physical properties that make them one of the most promising building blocks for future nanotechnologies. They may in particular play an important role in the development of innovative electronic devices in the fields of flexible electronics, ultra-high sensitivity sensors, high frequency electronics, opto-electronics, energy sources and nano-electromechanical systems (NEMS). Proofs of concept of several high performance devices already exist, usually at the single device level, but there remain many serious scientific issues to be solved before the viability of such routes can be evaluated. In particular, the main concern regards the controlled synthesis and positioning of nanotubes. In our opinion, truly innovative use of these nano-objects will come from: i) the combination of some of their complementary physical properties, such as combining their electrical and mechanical properties, ii) the combination of their properties with additional benefits coming from other molecules grafted on the nanotubes, and iii) the use of chemically- or bio-directed self-assembly processes to allow the efficient combination of several devices into functional arrays or circuits. In this article, we outline the main issues concerning the development of carbon nanotubes based electronics applications and review our recent results in the field

Bottom-up synthesis of porphyrin based graphene nanoribbons and nanomeshes

International audienceThe outstanding properties of graphene strongly inspire the scientific community at both the fundamental and applicative levels for high performance electronics, low power spintronics, renewable energy, composites materials and biomedicine. However, along this way several key scientific issues have to be addressed and one of the main challenges is the control and modification of graphene electronic properties, and notably the controlled opening of a sizable bandgap. This can be achieved by quantum confinement, by means of the fabrication of nano-objects with a precise control of the topology, edge-effects... As a consequence, two main graphene forms have emerged for electronic applications, Graphene NanoRibbons (GNR) and Graphene NanoMeshes (GNM). For the last decade, a great attention has been paid to the fabrication of GNRs and GNMs using conventional top-down approach (lithography, etching, thermal treatments). However, this approach does not allow manipulating the material at the atomic scale. In order to truly control the morphology and the composition of the materials and of its edges, the bottom-up approach is the relevant way to proceed. Recently, graphene incorporating porphyrin molecules have been designed either by the groups of Barth and Fischer. Here we report on the synthesis of porphyrin derivatives that can lead to nitrogen doped GNR and GNM. The strategy we applied was to design building blocks based on porphyrins with halogens connectors and polymerize them on metallic surface under Scanning Tunnelling Microscope (STM). We succeeded in the synthesis of two original porphyrins with reasonable yield. The first one is a tetrabromoanthracenyl porphyrin (BrTAP, Fig. 1) with four connectors for the formation of a 2D nanostructure and a second, a bis-bromoanthracenylporphyrin (BrBAP) with two connectors GNR. Preliminary STM image for BrTAP on Ag (111) is shown Fig. 1 and other catalytic surfaces are under investigation to form GNR and GNM

Carbon Nanotube and Porphyrins:Materials for Optics and Energy Applications

International audienceThe fabrication of functional hybrid materials that preserves and combines the properties of their building blocks is a central issue of nanosciences. Among the different classes of nanomaterials, carbon nanotubes are promising for electronics, opto-electronics, catalysis and composite applications. In this context the combination of nanotubes with porphyrins has been widely explored for catalytic or electron transfer purposes. Here I present two results obtained recently on the nanotube/porphyrincomposites, the first deals with the supramolecular organization in micelles of porphyrins around the nanotubes. In this work we were able to explain the Davidoff splitting observed on the absorption bands of the porphyrins by their organization around the nanotubes. The second deals with the synergic effect on catalytic activity of carbon nanotubes and strapped iron porphyrin hybrids for Oxygen Reduction Reaction (ORR). In particular, we demonstrated that the combination of both components - MWNTs and porphyrin - leads to a better catalytic activity than those of the nanotubes or the porphyrins taken separately.This study highlights the importance of the carbon support for the catalysis. The nanotubes ensure the availability of electrons to the porphyrin catalysts and allow the ORR to occur via the 4-electron pathway, avoiding the production of hydrogen peroxide