Simone Silvestrini

Synthesis and Photochemical Applications of Processable Polymers Enclosing Photoluminescent Carbon Quantum Dots

Herein, we propose convenient routes to produce hybrid-polymers that covalently enclosed, or confined, N-doped carbon quantum dots (CQDs). We focus our attention on polyamide, polyurea-urethane, polyester, and polymethylmetacrylate polymers, some of the most common resources used to create everyday materials. These hybrid materials can be easily prepared and processed to obtain macroscopic objects of different shapes, i.e., fibers, transparent sheets, and bulky forms, where the characteristic luminescence properties of the native N-doped CQDs are preserved. More importantly we explore the potential use of these hybrid composites to achieve photochemical reactions as those of photoreduction of silver ions to silver nanoparticles (under UV-light), the selective photo-oxidation of benzylalcohol to the benzaldehyde (under vis-light), and the photocatalytic generation of H2 (under UV-light).

Functional palladium metal films for plasmonic devices: an experimental proof

Palladium-based, Inverted surface plasmon resonance substrates with functional surfaces are presented and characterized. The advantages of the use of palladium in lieu of other metals (most notably gold) are discussed and assayed experimentally. We demonstrate how the bare metal films can be functionalized by thiol chemistry or by adsorption of functional graphene sheets and how the features of the surfaces affect the performance of the substrate.

A comparative electron paramagnetic resonance study of expanded graphites and graphene

Graphene, a novel electronic system with unprecedented characteristics, can be obtained using different methods, each producing materials with specific characteristics from the electronic point of view. Among these procedures, methods based on the expansion of graphite allow to obtain graphene material in rather high quantities. We have, then, conducted a comparative study of graphene materials produced by these methods by using electron paramagnetic resonance (EPR) techniques; single-layer commercial graphene produced using the Hummers method has been used as the reference. EPR techniques enable the study of some magnetic properties of different types of electrons exhibiting paramagnetic nature. We have analysed the EPR spectra to identify the different types of paramagnetic centres contributing to the spectrum. The analysis of the temperature-dependent EPR spectra and the use of pulse techniques allowed us to separate and characterize the contribution of free conduction electrons from the contributions of localized edge states and molecular-type paramagnetic states.

Tailoring the wetting properties of thiolene microfluidic materials

A post functionalization method for the control of the wettability of thiolene resins of the NOA family is presented. Treatment of open model surfaces or closed microchannels with chlorosilane derivatives resulted in dramatic changes in the behaviour of droplets and streams contacting the surfaces. The experimental findings are confirmed by the fabrication of a Y-junction device that works as a passive valve for water streams.

Photocontrolled Self‐Assembly of a Bis‐Azobenzene‐Containing α‐Amino Acid

Financial support from the Ministerio de Ciencia e Innovacion-FEDER (grant CTQ2010-17436, FPU fellowship to P.F.), Gobierno de Aragon-FSE (research group E40), and the University of Padova (PRAT A. M. C91 J11003560001 and M. M. CPDA119117) are gratefully acknowledged.

Immobilization of (60)fullerene on silicon surfaces through a calix(8)arene layer

In this work, we report the functionalization of flat Si(100) surfaces with a calix[8]arene derivative through a thermal hydrosilylation process, followed by docking with [60]fullerene. Chemical grafting of calix[8]arene on silicon substrates was evaluated by X-ray photoelectron spectroscopy, whereas host-guest immobilization of fullerene was demonstrated by atomic force microscopy and sessile drop water contact angle measurements. Surface topographical variations, modelled on the basis of calix[8]arene and [60]fullerene geometrical parameters, are consistent with the observed morphological features relative to surface functionalization and to non-covalent immobilization of [60]fullerene.

Novel 5-(Benzo[b]thiophen-3-yl)pyridine-3-carbaldehyde (BTPA) Functionalization Framework For Modulating Fullerene Electronics

Abstract Through a cycloaddition reaction, fullerene (C60) was derivatized with a novel organic compound 5‐(benzo[b]thiophen‐3‐yl)pyridine‐3‐carbaldehyde to form the processable and stable 3‐(benzo[b]thiophene‐3yl)‐5‐fullero‐1‐methylpyrrolidinepyridine (BTFP) compound. BTFP exhibits close similarities to phenyl‐C61‐butyric‐acid‐methyl‐ester (PCBM) in terms of first reduction potential values (−0.62 and −0.61 V vs. Ag/AgCl, for BTFP and PCBM, respectively) and lowest occupied molecular orbital (LUMO) energy level values (3.93 eV in both cases). In chloroform, BTFP exhibits a bathochromic shift in the λ max of BTFP (λ max,BTFP=290 nm and λ max,PCBM=260 nm), owing to the grafted benzo[b]thiophene‐3‐yl)pyridine moiety. Despite the similarity in LUMO (3.93 eV) energy values, BTFP and PCBM differ in their luminescence‐quenching ability. The bathochromic shift in the λ max of BTFP (relative to PCMB) is likely to contribute to improved light absorption of a suitable donor for photovoltaic applications.

Graphene-metal interfaces for biosensors devices

Graphene–metals interfaces are investigated in many subject areas both applicative and speculative. The interest mainly stems from the possibility for CVD synthesis of large area graphene on metals. In this case the metal acts as a catalyst for complete dehydrogenetaion of hydrocarbon precursors that leaves carbon behind at the surface. Such bilayer are also very appealing for surface plasmon resonance devices, since graphene acts both as a protective layer and biorecognition element. Several pairs of graphene–metal interfaces have been studied in terms of SPR performance and physicalchemical properties at the interface. With regard to this last aspect, NEXAFS spectroscopy is a powerful method to study single-, double-, and few- layers graphene and to illustrate any evolution of the electronic states.

Optical and structural properties of graphene oxide-noble metal bilayers

The practical use of graphene and graphene oxide beyond the research laboratories is strictly related to the fine tuning of new methodologies for processing and mass–production purposes. The photoreduction processing is an innovative route allowing exquisite control of the optoelectronic properties of graphene–like materials irradiated by coherent and incoherent light. We have investigated the effects induced by a mercury lamp on graphene/palladium bilayer; the change on the optical properties of the sample has been detected by using a surface plasmon resonance setup. The analysis, the perspectives and the preliminary results are shown thereafter.