IREU | Summer Projects in Italy

U.S. undergraduate students may select from amongst the following projects offered by the University of Perugia (Perugia, Italy) for the 2014 summer ACS IREU:

(PER.1) Synthesis and characterization of inorganic nanoparticles with controlled photoinduced behaviour

Prof. Loredana Latterini

Inorganic nanostructures having a defined morphology and structure, controlled at nanometric level, with tunable and engineered band gap represent a new and interesting class of materials with potential applications in photovoltaic devices, in electronic and optoelectronic materials. Among various processes to synthesize nanomaterials (such as SiO2, TiO2, ZnO, etc.), sol-gel methods appear to be one of the most versatile and cost-effective processes for producing nanomaterials in various shapes and forms. Changing the structure of precursors allows affecting the porosity of the nanomaterials and thus the density of the inorganic nanomatrix and its surface properties; while adjusting the preparation conditions allows controlling the size and shape of the nanoparticles thus engineering their band gap. In particular, the synthesis in controlled conditions or in a coordinating environment will ensure nanometer dimensions and/or defined aspect ratios. These parameters will allow tuning the material band gap and hence the efficiency of charge injection from an organic/inorganic photosensitizer and charge transport along one preferential direction.

On the other hand, the controlled entrapment of organic fluorophores in semiconductor nanoparticles can lead to an increase of the dye photostability and emission intensity (brightness) with respect to the free molecules. Such improved performances result from the prevention or reduction of quenching phenomena, the loss of degree of freedom and the confinement of defined molecular configurations in nanospace thus controlling their optical properties. The project involves the development of methods for the preparation of semiconductor nanoparticles or dye-doped semiconductor nanoparticles with design dimensions, porosity and surface properties and the nanomaterial characterization using optical, electron, and scanning probe microscopy, as well as different spectroscopic techniques. Then the photochemical behavior of the nanoparticle suspensions will be investigated and the results used to modify the preparation procedures in order to achieve a full control over the optical response of the material (fluorescence enhancement, electron transfer, photoreactions, etc.).

The summer research program consists of many small projects comprising different methods and techniques which can be easily accomplished in a few weeks. IREU students involved in this project will have the opportunity to choose from relatively simple projects related to synthesis and characterization of nanoparticles to more sophisticated procedure to investigate and analyze the photoinduced reactions of the nanomaterials. The program provides various levels of complexity that will satisfy abilities and needs of different students. 

(PER.2) Designing metal fragments for catalytic water oxidation

Dr. Alceo Macchioni

Water oxidation to molecular oxygen is an essential process for implementing an artificial photosynthetic apparatus aimed at the splitting of H2O into H2 and O2, whose realization would contribute to solve the worldwide energetic problem in a green and sustainable way. Water oxidation is intrinsically a difficult process consisting in the abstraction of four electrons from two water molecules. In addition of having a disadvantageous thermodynamics, the process shows overpotentials that makes it difficult also from the kinetic point of view. Hence, an efficient catalytic system becomes necessary, capable of interfacing the monoelectronic charge separation process with the multielectron oxidative and reductive processes.

At the present, only a few metal complexes capable to oxidize water are known but their performances are still much lower than those of the catalytic system acting in the natural photosynthesis process. Furthermore, the reaction mechanism of the oxidation process for most of them is almost completely unknown.

We aims at (1) designing and synthesizing new organometallic compounds for the catalytic splitting of water and testing them in catalysis, (2) investigating the reaction mechanism of water oxidation by means of classical spectrophotometric techniques (UV-VIS) and advanced NMR techniques and (3) anchoring the catalysts with the best performances on regular polymeric structures, as for instance dendrimers, or on solid surfaces.

Summer projects for undergraduates will involve synthesis, characterization and test of new iridium organometallic catalysts for water oxidation. In the course of their research projects, students will learn synthetic procedures, NMR techniques for the intra- and inter-molecular characterization, catalytic tests based on UV-VIS spectroscopy.

(PER.3) Ab-initio study of charge displacement in water’s intermolecular interactions

Prof. Francesco Tarantelli

While the interaction energy surfaces of water with a large number of other chemical systems have been extensively and accurately studied, very little still is known about the very nature of these non-covalent interactions beyond standard van-der-Waals models. As a result, while water is the most ubiquitous and arguably the most important chemical species for the sustainment of life on earth, there are still severe limits to our understanding of hydrogen-bonding, of solvation, and of other important interactions of water in atmospheric and interstellar chemistry.

We propose to use our recently introduced theoretical analysis of the electron charge displacement taking place upon formation of a chemical interaction to obtain useful and detailed information on the nature of intermolecular forces. A wide choice of molecular complexes, typically of small to medium size will be studied. In particular, we focus on the role played by charge-transfer components and attempt to explain the marked directionality which appears to be so peculiar of water’s interactions. The electron density studied in these investigations is obtained by the most accurate quantum-chemical methods available today.

As previous experience has shown, due to the small size of the molecules studied and the high degree of modularity of the project, some of these investigations are ideally suited to be carried out by an IREU student in few weeks. The subject matter is of basic, general appeal, and oriented towards the illustration of fundamental aspects of chemical bonding. The visiting student will be gradually exposed to the underlying theoretical models and rapidly enabled to carry out calculations in autonomy, using the most popular ab-initio programs.

(PER.4) Environmentally-friendly methodologies for the preparation of organic semiconductors towards the fully green production of solar electricity

Prof. Luigi Vaccaro

Despite the latest impressive results, further significant enhancement in organic photovoltaic performance is necessary in order to meet the requirements for large-scale commercialization as a renewable energy source.
Besides, the high environmental cost associated with the currently available methodologies for the synthesis of organic semiconductors, represents a serious limitation for the future application of these compounds as green alternatives to silicon-based devices.

In this context, Green chemistry principles should be applied for the definition of more environmentally efficient synthetic methodologies able to turn the Organic PV approach fully green.

According to our expertise, organic semiconductors will be prepared by minimizing the use of toxic organic solvents and by defining innovative synthetic procedures using green alternative reaction media such as water or solvent-free conditions (SolFC). In addition, new solid catalytic systems will be designed and prepared in order to minimize the catalyst’s dispersion.

The fully green synthetic approach include also the minimization of costly labor and the possibility of producing the desired materials in large scale quantity at the minimal environmental cost. In fact, it is planned the definition of automated protocols by realizing cyclic continuous-flow reactors operating under solvent-free conditions. This approach is very promising to keep the best efficiency of the catalyst making very simple and reproducible its recovery and reuse.

Undergraduates students can participate this research by choosing small projects concerning the catalyst preparation, the reaction condition optimization or the scale-up process for the set-up of a continuous-flow reactor and the definition of automated protocols.

Up to three students can profitably fit into ongoing research being supervised by post-doc fellows who will help to finalize their piece of work into a scientific publication on a specialized journal (as it happened in the previous year).