Three-color plasmon-mediated reduction of diazonium salts over metasurfaces.

Surface plasmon-mediated chemical reactions are of great interest for a variety of applications ranging from micro- and nanoscale device fabrication to chemical reactions of societal interest for hydrogen production or carbon reduction. In this work, a crosshair-like nanostructure is investigated due to its ability to induce local enhancement of the local electromagnetic field at three distinct wavelengths corresponding to three plasmon resonances. The structures are irradiated in the presence of a solution containing diazonium salts at wavelengths that match the resonance positions at 532 nm, 632.8 nm, and 800 nm. The resulting grafting shows polarization and wavelength-dependent growth patterns at the nanoscale. The plasmon-mediated reactions over arrays of the crosshair structures are further investigated using scanning electron microscopy and supported by finite domain time domain modelling revealing wavelength and polarization specific reactions. Such an approach enables nanoscale molecular printing using light source opening multiplexing applications where different analytes can be grafted under distinct opto-geometric conditions

Three-color plasmon-mediated reduction of diazonium salts over metasurfaces.

Surface plasmon-mediated chemical reactions are of great interest for a variety of applications ranging from micro- and nanoscale device fabrication to chemical reactions of societal interest for hydrogen production or carbon reduction. In this work, a crosshair-like nanostructure is investigated due to its ability to induce local enhancement of the local electromagnetic field at three distinct wavelengths corresponding to three plasmon resonances. The structures are irradiated in the presence of a solution containing diazonium salts at wavelengths that match the resonance positions at 532 nm, 632.8 nm, and 800 nm. The resulting grafting shows polarization and wavelength-dependent growth patterns at the nanoscale. The plasmon-mediated reactions over arrays of the crosshair structures are further investigated using scanning electron microscopy and supported by finite domain time domain modelling revealing wavelength and polarization specific reactions. Such an approach enables nanoscale molecular printing using light source opening multiplexing applications where different analytes can be grafted under distinct opto-geometric conditions

Extending nanoscale patterning with multipolar surface plasmon resonances.

Plasmonic excitation of metallic nanoparticles can trigger chemical reactions at the nanoscale. Such optical effects can also be employed to selectively and locally graft photopolymer layers at the nanostructure surface, and, when combined with a surface functionalization agent, new pathways can be explored to modify the surface of a plasmonic nanoparticle. Among these approaches, diazonium salt chemistry is seen as an attractive strategy due to the high photoinduced reactivity of these salts. In this work, we demonstrate that it is possible to trigger the site-selective grafting of aryl films derived from diazonium salts on distinct nano-localized area of single gold nanotriangles, by taking advantage of their multipolar localized surface plasmon modes. It is shown the aryl film will preferentially graft in areas where the electric field enhancement is maximum, independently of the considered excited surface plasmon mode. These experimental findings are in very good qualitative agreement with the calculations of the local electric field, using the finite-difference time-domain (FDTD) method. We believe that this plasmonic-based approach will not only pave a new way for the spatially controlled surface functionalization of plasmonic nanoparticles, but also provide a general strategy to attach distinct molecules to hot spot regions on a single nanoparticle, opening promising prospects in sensing and multiplexing, and optically nano-scale patterning of functional groups

Preparation and optical properties of novel bioactive photonic crystals obtained from core-shell poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) microspheres

Optical properties of polymer microspheres with polystyrene cores and polyglycidol-enriched shells poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol) (P(S/PGL) particles with number average diameters Dn determined by scanning electron microscopy equal 237 and 271 nm), were studied before and after immobilization of ovalbumin. The particles were synthesized by emulsifier-free emulsion copolymerization of styrene and polyglycidol macromonomer (poly(styrene/α-tert-butoxy-ω-vinylbenzyl-polyglycidol)) initiated with potassium persulfate. Molar fraction of polyglycidol units in the interfacial layer of the microspheres determined by XPS was equal 42.6 and 34.0%, for the particles with Dn equal 137 and 271 nm, respectively. Colloidal crystals from the aforementioned particles were prepared by deposition of particle suspensions on the glass slides and subsequent evaporation of water. It was found that optical properties of colloidal crystals from the P(S/PGL) microspheres strongly depend on modification of their interfacial layer by covalent immobilization of ovalbumin. The coating of particles with ovalbumin resulted in decreasing their refractive index from 1.58 to 1.52

POLYMERES CONDUCTEURS POUR L'ADRESSAGE MOLECULAIRE DES METAUX DE TRANSITION

NOUS AVONS PU MONTRE DANS CE TRAVAIL LA POSSIBILITE D'ETABLIR UNE COMMUNICATION ELECTRONIQUE ENTRE LES CHAINES DE POLYMERES CONDUCTEURS ET DES COMPLEXES DE METAUX DE TRANSITION DIRECTEMENT GREFFES SUR LES CHAINES. CET EFFET EST INDUIT SANS CHANGER L'INDIVIDUALITE DE CHAQUE SOUS-UNITE. EN JOUANT SUR L'ETAT DU POLYMERE CONDUCTEUR, C'EST-A-DIRE SUR LE POTENTIEL APPLIQUE A L'ELECTRODE, NOUS AVONS PU MODIFIER LA DENSITE ELECTRONIQUE DES LIGANDS AFIN D'INDUIRE AU NIVEAU DU CENTRE METALLIQUE DES EFFETS ANALOGUES A CEUX OBSERVES CLASSIQUEMENT DES QUE L'ON MODIFIE LA SPHERE DE COORDINATION PAR VOIE CHIMIQUE. NOUS AVONS PU VERIFIER DANS UNE ETAPE PRELIMINAIRE QU'UN CENTRE ACTIF PHENYLE, PRESENTANT UNE SIGNATURE EXPERIMENTALE FORTE LIEE UNIQUEMENT A DES EFFETS ELECTRONIQUES, POUVAIT ETRE DIRECTEMENT INFLUENCE PAR L'ETAT D'OXYDATION DU POLYMERE CONDUCTEUR DANS LE CAS SEULEMENT OU LE LIEN AVEC LE POLYMERE CONDUCTEUR EST CONJUGUE. DES EFFETS SIMILAIRES ONT ETE OBSERVES SUR UNE SYSTEME POLYMERE PLUS ELABORE, OBTENU PAR ELECTROPOLYMERISATION D'UN MONOMERE COMPORTANT UNE CAVITE COMPLEXANTE GREFFEE SUR UNE UNITE TERTHIOPHENE : UN TEL PROCEDE PRESENTE L'AVANTAGE D'OBTENIR DES CAVITES COMPLEXANTES DISPOSEES DE MANIERE REGIOREGULIERE LE LONG DES CHAINES ET EN INTERACTION ELECTRONIQUE AVEC LES CHAINES DE POLYMERE CONDUCTEUR. PAR LA SUITE, NOUS AVONS ANALYSE, PAR SPECTROSCOPIE XPS ET SAX, LE POLYMERE HYBRIDE POLY(OTBA-CU), CE QUI A PERMIS DE METTRE EN EVIDENCE EXPERIMENTALEMENT UNE MODIFICATION SENSIBLE A LA FOIS DE LA DENSITE ELECTRONIQUE AU NIVEAU DE L'ION CU 2 + MAIS EGALEMENT DES DISTANCES METAL-LIGAND LORS DU CHANGEMENT D'ETAT REDOX DU POLYMERE. PAR AILLEURS, L'ANALYSE DES PROPRIETES MAGNETIQUES DE NOS MATERIAUX A MIS EN EVIDENCE QUE CEUX-CI PRESENTENT NON SEULEMENT DES PROPRIETES CARACTERISTIQUES DES CHAINES CONDUCTRICES MAIS AUSSI UN ORDRE MAGNETIQUE A LONGUE DISTANCE ANALOGUE A CELUI DE CHAINES MAGNETIQUES 1 D.PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Magnetic Fe 2 O 3 −Polystyrene/PPy Core/Shell Particles: Bioreactivity and Self-Assembly

International audienceThis paper describes the synthesis of new magnetic, reactive polystyrene/polypyrrole core/shell latex particles. The core consists of a polystyrene microsphere containing gamma-Fe2O3 superparamagnetic nanoparticles (PSmag), and the shell is made of reactive N-carboxylic acid-functionalized polypyrrole (PPyCOOH). These PSmag-PPyCOOH latex particles, average diameter 220 nm, were prepared by copolymerization of pyrrole (Py) and the active carboxyl-functionalized pyrrole (PyCOOH) in the presence of PSmag particles. PNVP was used as a steric stabilizer. The functionalized polypyrrole-coated PSmag particles were characterized in terms of their particle size, surface morphology, chemical composition, and electrochemical and magnetic properties using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry, and SQUID magnetometry. Activation of the particle surface carboxyl groups was achieved using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS), which helps transform the carboxyl groups into activated ester groups (NSE). The activated particles, PSmag-PPyNSE, were further evaluated as bioadsorbents of biotin used as a model biomolecule. It was shown that biotin was immobilized at the surface of the PSmag-PPyNSE particles by forming interfacial amide groups. The assemblies of PSmag-PPyCOOH particles on glass plates were further investigated. When no magnetic field is applied, the particles assemble into 3D colloidal crystals. In contrast, under a magnetic field, one-particle-thick chains gathered in hedgehog-like architectures are obtained. Furthermore, PSmag-PPyCOOH coated ITO electrodes were shown to be electroactive and electrochemically stable, thus offering potentialities for creating novel high-specific-area materials for biosensing devices where the conducting polymer component would act as the transducer through its conductive properties

Grafting of borane-protected aliphatic and aromatic aminophosphine ligands to glassy carbon electrodes

Phosphine–borane moieties with amino-anchoring groups were covalently grafted on glassy carbon substrates, using free radical electrografting methods. The oxidative destruction of phosphine was efficiently quenched thanks to the borane protecting group. The chelating ability of the attached phosphine ligands was exemplified with Mn. Keywords: Amine oxidation, Diazonium, Surface modification, Phosphine–borane ligan

Photonic crystal pH sensor containing a planar defect for fast and enhanced response

This paper describes the introduction of a planar defect layer within inverse opal hydrogels for the elaboration of tunable photonic crystal pH sensors with enhanced optical properties. We demonstrate a mechanically robust, highly sensitive and fast response photonic crystal fabricated by a stepwise strategy combining the Langmuir-Blodgett technique and the photonic crystal template method. The resulting material consists of a three-dimensional, highly-ordered and interconnected macroporous array of poly(methacrylic acid), which is a hydrogel sensitive to pH. The optical properties of these inverse opals were investigated using reflection spectroscopy. The defect layer was shown to enhance both the sensitivity and the response time of the photonic crystal sensing materials