Sigma Delocalisation via Group 13 Homocatenation

Organic polymers have many well-established uses in everyday life. Plastics, elastomers, films and fibres are used in areas as diverse as clothing, car tyres, compact discs, packaging materials and prostheses. By contrast the chemistry of polymers featuring inorganic elements is generally at a much more primitive state of development due a paucity of suitable synthetic routes. Nevertheless, incorporation of main group or transition metals into a polymer main chain can lead to interesting and useful properties, such as low temperature flexibility, high thermal and oxidative stability and intriguing electrical and optical characteristics arising from unusual electronic effects such as delocalisation of sigma-electrons. This proposal seeks to build upon our recent report in Science that group 13 centres, when linked in extended linear chains, display delocalised electronic properties. Similar properties are currently the preserve of pi-conjugated 'plastic electronic' materials such as polythiophene and polyacetylene which are of interest in a wide array of possible applications, from solar cells and light emitting devices to molecular computing . In the case of our target molecules the electroactivity is a result of delocalisation of the electrons along the sigma backbone of the polymeric unit. We shall devise new routes to a variety of polymeric systems based upon all the elements of group 13 (excepting thallium) and will test our hypothesis that the electronic band gaps will be largely dependent upon the identity of the constituent group 13 element both experimentally and theoretically.