[Todos] PROXIMO SEMINARIO

[Fernando V. Molina]

Jueves 6 de marzo de 2008 - 13 hs

Aula de Seminarios del INQUIMAE, 3er piso Pab. II



Prof. Antonio Sgamellotti
Dipartimento di Chimica, CNR-ISTM and UdR INSTM
University of Perugia, Via Elce di Sotto 8, 06123 Perugia



THEORETICAL INVESTIGATIONS ON CARBON NANOTUBES: 
SIDEWALL FUNCTIONALIZATION AND ENCAPSULATION OF NANOCRYSTALLITES

Abstract:
The investigation of nanostructured systems and 
materials is currently a topic of great interest, 
in view of future technological applications. In 
this field modelling plays an important role; 
theoretical calculations provide insight into the 
microscopic properties and behaviour of these 
systems. In this work we present  theoretical 
investigations on the properties of carbon 
nanotubes (CNTs), one of the most studied and 
promising species in the field of nanotechnology.
The chemical functionalization of CNTs represents 
an attractive target for study, since it can 
improve their solubility and processability. 
Accurate theoretical investigations of 
functionalized CNT may clarify the effects of 
chemical modifications on their electronic and 
structural properties. Static and dynamical 
density functional theory calculations have been 
performed to analyze the interaction of different 
species with CNTs. The areas of applications 
considered in this work include several 
functionalization routes and related properties. 
As a first example, investigations have concerned 
the functionalization of CNTs with transition 
metal complexes, which is found to affect the 
electronic properties of the adduct. Moreover, 
the interaction between small molecules and the 
CNT sidewall has been analyzed in order to 
investigate eventual technological applications 
of CNTs in fields like gas-sensing or hydrogen 
storage in nanostructured fuel cells. In all 
cases, special attention has been devoted to the 
definition of proper models for the sidewall, 
which constitute a mandatory step to achieve the required accuracy.
Another field of investigation has concerned the 
confined growth of ionic species by encapsulation 
in CNTs, which has recently attracted growing 
interest. The ability to encapsulate different 
materials has indeed constituted one of the first 
applications of CNTs. Besides the possibility of 
creating intrinsically monodimensional materials 
through nanotube-driven template syntheses, one 
of the most interesting aspects of encapsulation 
concerns the formation of ordered structures in 
the hollow of CNTs, in the form of 
nanocrystallytes. The one-dimensional confined 
growth of different compounds has been viewed as 
a suitable route to the development of new 
low-dimensional materials, like nanowires. In our 
work, the morphologies of AgI nanocrystallites 
grown inside (n,n) single-walled CNTs are 
investigated by means of molecular dynamics 
simulations. All crystal structures found are 
formally constituted by (n,m) AgI nanotubes, with 
chiral vectors n and m depending on the CNT 
diamenter and on the local environment. In 
particular, for narrow CNTs unprecedented 
low-dimensional AgI nanoribbons appear, actively 
stabilized by a deformation of the CNT, as 
observed in experiments. In larger diameter CNTs, 
inorganic (n,m) AgI nanotubes are typically 
formed, giving rise to a scenario of polymorphism in the nanoregime.
An extention of the Clar sextet theory of 
aromatic systems is proposed for finite-length 
models of metallic and semiconducting carbon 
nanotubes (CNTs). For metallic CNTs, the 
electronic properties of finite-length models 
converge monotonically to the values expected for 
quasi-monodimensional metallic systems. For 
semiconducting CNTs, the use of finite-length 
models leads to a fast convergence of the 
electronic properties to the values expected for 
the corresponding infinite nanotube.

Curriculum vitae

Full Professor of Inorganic Chemistry, University 
of Perugia, since the 1st November 1975.
Member of the National Chemistry Committee of the 
CNR Italian Research Council (1988-1994).
Coordinator of the Institutional Fellowship 
(Perugia, Heidelberg, Lausanne) of the Human Capital and Mobility (1992-1994).
Chairman of the CERC3 (Chairmen of the European 
Research Councils Chemistry Committees) (1992-1994).
Responsible of International Collaborative 
Research Projects with the Universities of 
Heidelberg, Lausanne, Durham and with the Daresbury Laboratory.
Member of the Steering Committee of the ESF 
(European Science Foundation) scientific program 
"Relativistic effects in heavy element chemistry and physics".
Member of the scientific committee of CECAM 
(Centre Europeen de Calcul Atomique et Molèculaire).
Italian representative of the European COST 
project on Chemistry. Chairman of the Management 
Committee of the COST Action D3 "Theory and 
modelling of chemical systems and processes" (1992-1994).
Coordinator of the COST Chemistry Project 
D3/0002/92 and D9/0005/97 (Perugia, Lausanne, 
Heidelberg, Daresbury) (1992-1995).
Chairman of the Scientific Committee of the 
PQE2000 (for high performance computing), with 
the involvement of CNR, INFN, ENEA, QSW (Alenia Spazio/MEIKO).
Member of the EC evaluation panel "Large Scale Facilities"
President of the Centre of the Excellence SMAArt 
"Scientific Methodologies applied to Archaeology 
and Art" approved and financed by Murst the 2nd 
April 2001, at the University of Perugia.
Member of the CNR Executive Committee (1999-2003).
Member of G8 panel on "Research Assessment".
Member of the panel on "Materials" at the ESRF Grenoble.
External Advisor of the ERA-NET CHEMISTRY
National Coordinator of the "Cultural Heritage" 
Group of INSTM (National Consortium of Materials Science and Technology)
Partner of European Project LabS TECH 
(Laboratories on Science and Technology for the 
conservation of European Cultural Heritage) (5° 
P.Q.) and Eu-ARTECH (Access, Research and 
Technology for the conservation of the European Cultural Heritage) (6°P.Q.)
Chairman of the committee for the University 
degree in "Sciences and Technologies for the 
Conservation and Restoration of the Cultural Heritage"
Author of about 300 scientific publications in 
international journals concerning advanced 
computations on chemistry, electronic and 
structural properties of molecules and inorganic 
materials, spectroscopic properties and 
characterization of archaeological and art-historical artefacts.
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