Grant: Discovery Grants Program - Individual

Conductive polymers have traditionally been built on organic frameworks and often require oxidative or reductive doping to effectively conduct electricity. These conductive organic plastics rely on a delocalized pi network and small band gaps in order to transport electrons. Unlike carbon based intrinsically conducting polymers, inorganic homopolymers with backbones of silicon, germanium or tin atoms utilize sigma delocalization to be conductive. Of these Group 14 elements, the homopolymers of tin best emulate its elemental form and display semi-conducting properties in its natural state and can be made highly conducting when doped. The promise of fabricating devices or preparing one-dimensional conductive polymeric wires with these materials has been hampered by their extreme light and moisture sensitivity. In this proposal, a new strategy to incorporate higher coordinate tin species (datively bonded 5- or 6-coordinate tin) with light absorbing side groups should provide the best opportunity to deliver light and moisture stable polystannanes. Higher coordination numbers at tin through dative interactions with oxygen or nitrogen atoms effectively protects the sensitive Sn-Sn bonds from nucleophilic attack by blocking access to a coordination site. Additionally, the presence of a UVA (ultra-violet absorbing small molecule) group to capture photons reduces the likelihood of photoscission in the homopolymers. The design of a series of new tin dihydride monomers and subsequent polymerization by dehydrocoupling will be undertaken. These new polymers should display dramatic differences in stability and conduction properties compared to regular polystannanes. Central to all these investigations will be the training of undergraduate and graduate students in the skills and techniques of preparing and characterizing main group inorganic polymers. This work proposes to dramatically expand the knowledge and usefulness of Group 14 polymers, in particular, polystannanes. It will lead to advances in both inorganic chemistry and inorganic polymers, and provide the best opportunity to make conductive polymeric wires with tin.