Andreas Mayr
Department of Chemistry, State University of New York at Stony Brook,
Stony Brook, NY 11794-3400
E-mail: amayr@notes.cc.sunysb.edu
Phone: (631) 632-7951
Fax: (631) 632-7960
On account of their size-dependent electronic and magnetic properties,
clusters are promising as components for integrated devices capable of
sensing, transferring, processing, and storing information. The availability
of readily manipulable clusters would, for example, enable the development
of extremely powerful new computer architectures based on the principles
of single-electronics. Yet while the potential of clusters for such
applications has been recognized for some time, practical implementations
have not been forthcoming as fast as desirable. Some of the major
problems are associated with the difficulties to control the precise composition
and the spatial arrangement of clusters and nanostructures in general.
The need for exact reproducibility of composition and spatial arrangement
suggests that ideal clusters should be of molecular definition, have well-defined
external shapes, and exhibit selective surface functionalities.
A potential approach towards such well-defined clusters is discussed.
It is based on molecular cubes of sufficient size to serve as hosts for
clusters. The molecular cubes consist of linear organic units as
the edges and rectangular trigonal pyramidal transition metal complex fragments
as the corners. These covalent frameworks can be functionalized by
means of appended side chains to form internal cavities for the growth
of precisely defined clusters and for the specific recognition of individual
molecules. Via a different designated set of side chains, such frameworks
can be interconnected to form precisely defined cluster arrays which may
exhibit cooperative electronic or magnetic behavior.
The proposed molecular cubes provide structural frameworks for the
attachment of side chains bearing chemical functionalities. Since
there are no obvious limitations concerning the nature of these groups,
the complexity of a given nanocube can readily exceed that of a protein
of comparable size. With the unprecedented control over structure
and functional information content, the availability of the proposed molecular
cubes will open unforeseen possibilities in virtually all areas of molecular
materials. The potential impact will most likely be largest in areas
of information sensing and processing, because of the possibility to create
complex cluster arrays which are sensitive to minute external stimuli,
e. g. the absence or presence of single electrons or molecules, radiation,
and electric or magnetic fields.