Designing Moisture and Light Stable Group 14 Homo- and Alternating Polymers including Polystannanes

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Our research efforts at Ryerson over the last 4 years have focussed on the preparation of hypercoordinated (5-coordinate) stannane monomers suitable for polymerization. Mild metal-catalysed dehydrogenation of both flexible and non-flexible -C,O- and -C,N- ligands attached to tin dihydrides has led to the isolation of modest molecular weight, hypercoordinated polystannanes. These unique polymers demonstrate a significant improvement in light stability (> 90 d vs 10 min for poly(dibutyl)stannane) in both the solution and the solid state. The hypercoordinate polymers also display improved resistance to moisture (7 d at ambient vs 1 hr for poly(dibutyl)stannane), with access to tin-tin bonds hindered by the geometry of the sterically crowded tin centres. In our investigations, we have also discovered an accessible route to the preparation of alternating polystannanes via the room-temperature condensation of dialkyl and diaryl tin diamides with dialkyl and diaryl tin dihydrides. This condensation polymerization route has opened the possibilities to the preparation of uniquely designed polystannanes with customized functionality on every tin atom, or every other tin, as required. Our contribution to the advances in tin chemistry leading to more light and moisture stable polystannanes has made the end goal of achieving printable electronics from these intrinsic conducting materials a closer reality. We propose a continuation of these current efforts in the following specific areas: 1) Optimized Light and Moisture Stable High molecular weight film forming Polystannanes: This effort would seek to identify and prepare ligands which enhance overall stability, in particular moisture stability in 5-coordinate polystannanes. Alternating hydrophobic and light absorbing substituents would provide the essential combination of light and moisture stability for polystannanes. 2) Push-Pull Stannanes: Employ condensation chemistry of select tin diamides and tin dihydrides to access a series of intrinsic semi-conducting push-pull polystannanes. The construction of these polystannane materials must ensure facile polymer solubility, stability, and processability in terms of formulation for an inkjet printhead and retain the advantages of an intrinsic push-pull polymer wire. This will be ideally probed by cyclic voltammetry (to show stability) as well as conductivity measurement techniques to support these characteristics. 3) Alternating Group 14 polymers: This involves the condensation between dihydride or diamide stannanes and dihydride and diamide silanes, germanes and plumbanes. A careful match of chemistries is required to identify conditions that promote hybrid polymers of this type. No specific alternating Group 14 polymers are now known. This chemistry opens access to these previously unknown materials.