Toward the development of a graphene-based molecular sensor incorporating a polycyclic tripodal scaffold

This study has been undertaken in order to investigate the functionalisation of polyaromatic hydrocarbon cores (pyrene and perylene) and their interaction with graphitic surfaces, for potential application in the non-covalent modification of graphene for the generation of aqueous graphene-based dispersions and sensors. Graphene is a 2D-material that has been globally recognised for its potential to transform many technologies. Liquid-phase exfoliation of graphite is a promising strategy for ef- ficient mass-production of graphene. Water is an ideal solvent for industrial-scale pro- cessing, however the hydrophobic nature of graphene means a surfactant additive is re- quired. This study, in conjunction with that from other members of the group, has led to the synthesis of a series of pyrene and perylene structures where it has been established that insertion of alkyl spacers between a PAH core and a polar head group led to im- proved exfoliation efficiency. Graphene has excellent electrical properties and large surface area which could trans- form chemical sensors beyond the current limits of detection, however advances to en- sure selective responses toward target molecules are necessary. A series of monopodal and tripodal scaffolds, bearing one or three pyrene binding sites respectively and armed with a maleimide head group, were synthesised with a view to investigating their inter- action with representative thiols and sulfite anion. The non-covalent adsorption of these scaffolds onto a variety of surfaces was analysed by AFM and QCM, which suggested that the tripodal platform (3Py-Base, 29) has greater stability against desorption than its monopodal equivalent (1Py-Base, 28). A prototype nanofabricated graphene device showed an encouraging electronic response, which might be ascribed to the sensing re- action occurring on the surface of graphene.