dc.description.abstractenglish |
This Thesis deals with the chemistry and development of new hybrid
multifunctional systems based on carbon nanotubes (CNTs) and graphene (G). To
introduce both types of carbon nanoforms a brief historical overview of these
systems has been briefly given at the Preface. Next and prior to the presentation of
the results, two introductory chapters in which the principal aspects of the synthesis,
properties and applications of carbon nanotubes (chapter 1) and graphene (chapter
2) are given.
The results have been divided in three chapters:
Chapter 3 is related with the development of hybrid materials based on
CNTs, and it has been divided in two independent parts. The first part deals with the
modification of the walls of the carbon nanotubes (CNTs) to drive their interaction
with Mn4 single molecule magnets (SMMs). The deposition of SMMs along the
CNT surface may have implications in molecular magnetism, field in which the
organization of magnetic moieties along a conducting wire turns out to be essential.
Our approach implies the use of weak electrostatic interactions which contribute to
preserve the SMM structure. We will show how the magnetic properties of the
attached molecules are significantly affected by the grafting process. In the second
part, a hybrid between a photoactive polyoxometalate (POM) and single walled
carbon nanotubes (SWNTs) has been developed. In contrast to the first system, in
this case the POM has been conveniently modified with pyrene moieties capable to
bind to the unmodified walls of the SWNTs. The deposition of photoactive
molecules (POM) over CNTs may have important implications in photovoltaics and
other electronic devices. Moreover, we will describe the system at the atomic level
by the employment of microscopic techniques.
Chapter 4 focuses on the chemical synthesis of graphene (G). This chapter
has been divided in two parts. In a first part, G will be obtained from graphite oxide
(GO) by a hydrothermal (HT) method. In particular, our work deals with the
important role that the pH plays in the reduction of GO under HT conditions. An indepth description about the morphologies and characteristic of the prepared material
will be given. In a second part, a bottom up approach to synthesize graphite will be
described. With this aim, anthracene molecules have been used as starting material.
Afterwards, some ideas toward the synthesis of graphitic nanoforms following the
previous bottom up approach will be introduced.
Finally, chapter 5 is devoted to the chemical functionalization of graphene
via covalent bonds. In a first part, a general procedure to synthesize chemically
modified graphene (CMG) by simple functionalization/reduction of GO under
thermal treatment with DMF is described. The as-made CMG will be further
decorated with gold nanoparticles (Au NPs). Our approach introduces a degree of
control over the coverage of the CMG with Au NPs. We believe that the attained
system could be useful for a wide range of applications such as sensing, energy
storage, or catalysis. In a second part, a controlled doping of the layers with
paramagnetic radicals will be directly synthesized by chemical functionalization of
graphite through the Bingel-Hirsch cyclopropanation reaction. Those paramagnetic
moieties have shown to influence the magnetoresistance response of the hybrid by
the appearance of a low field magnetoresistance effect at low temperatures. This
kind of arrangement can have important in sensing applications. |
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