Bicomponent dendritic macromolecules: design and assembly of multifunctional nanomaterials

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This proposal aims at constructing well defined macromolecular heterostructures, and explores their potential in performing multiple predetermined functions, cooperatively and efficiently. These platforms that can provide a synergistic combination of individual and characteristic functionalities, makes them of relevance in a variety of areas including sensors, recognition/delivery vehicles and catalysis. The key to simplicity with which a library of these compositionally diverse dendrimers will be delivered, is the chemoselectivity of amino-stannanes towards acetylenes. Starting from a central core with two distinct focal groups, it will allow efficient build-up of one arm using aminosilanes, followed by second shell hierarchy outward using aminostannanes. The versatility of the approach offers the potential to introduce a variety of dendron structures with a tailored combination of backbones for desired functions. A detailed understanding of the self-organization of these diblock dendrimers that will be investigated extensively in solution and at interfaces, will provide a facile access to novel assemblies with regions of localized functional density. Dendrimers developed in this proposal will be used to fabricate a variety of size and shape controlled metallic nanoparticles. The spatially defined multimetallic systems that will be assembled using bifunctional dendrimers, are excellent candidates in designing co-operative catalysts that can carry out multiple organic transformations in a single pot. In addition, we shall explore self-assembly of a block of these dendrimers into discrete shapes, and then employ the second arm to synthesize nanoparticles at the resulting pre-determined positions. This provides a relatively simple supramolecular approach to fabricate morphologically controlled nanostructures which is essential for tailoring their unique behavior. The broader impact of this proposal is to build cumulative knowledge base on multi-component products, which will be extremely useful in assembling a wide variety of nanoscale structures, and will address key issues in chemistry and materials science.