The architecture of inorganic structures (on the microscopic to macroscopic length
scale) has become one of the most important parameters that can be manipulated in
order to optimize a structure for advanced applications. These structures are known
to possess interesting and useful optical, electronic and/or magnetic properties
that can subsequently be exploited in a wide variety of applications ranging from
novel forms of catalysis to solar energy conversion. The choice of application is
contingent on not only the chemical composition of the material but also on the overall
morphology, and even more precisely on the accessible surface area. Currently, there
are a myriad of methods available for fabrication of such intricate inorganic structures.
However, irrespective of employing a certain fabrication method, the formation of
well-organized materials is not trivial as various parameters have to be regulated.
These include uniformity of size, stabilization against collapse, consistency in
the chemical composition and growth of the overall structures with preferred morphology
(thin films, spheres, fibers, helical spirals etc.).
The principal aim of the research in our lab has been to augment the current understanding
of the concepts in supramolecular templating of inorganic materials for formation
of nanostructures. To be more precise, self-assembling amphiphilic structures (e.g.
synthetic or naturally occurring surfactants, peptides, and/or block co-polymers)
in the presence of diffusion-controlling media (such as gels, microemulsions, non-aqueous
solvents) are used to provide a temporary ‘scaffold’. This self-assembled template
provides a complex 3-dimensionsal structure which has features on the nanometer length
scale. Subsequently, colloidal inorganic building blocks (sol-gel precursors and/or
nanoparticles), when introduced into this media, are then organized (ideally) into
the inverse replica of the template. More importantly, this template, under appropriate
conditions, is able to exploit the principles of molecular recognition and in turn
structure-direct and size-constrain the condensing inorganic precursors. Interestingly,
cooperative assembly imparts intricate morphological characteristics to the products
that were previously unattainable.