Interest in arylene ethynylene oligomers and polymers is often fueled by the desirable electronic properties associated with these types of conjugated molecules. Two factors can explain the fact that para-arylene ethynylenes are much more sought after for these purposes than their isomeric ortho and meta relatives.  First, para conjugation pathways offer enhanced electron delocalization compared to ortho and meta counterparts. Second, ortho- and meta-arylene ethynylenes have the ability to fold into helices that distort the p-system from planarity, decreasing the effective conjugation of these oligomers.Current research efforts are directed toward addressing this second limitation in ortho-arylene ethynylene structures. Specifically, when pyrazine and pyridine rings are strategically placed throughout the arylene ethynylene molecule, the conjugated backbone can act as a ligand for appropriately sized transition metals. Metal cations with preferences for square planar (Pd (II)) and linear (Ag (I)) coordination environments can enforce planarity in the organic structure. This coordination-driven planarization can increase the effective conjugation of the backbone, making ortho-arylene ethynylenes more attractive targets for the development of organic electronic devices.

Manipulating the electronic properties of arylene ethynylenes via transition metal coordination

246th National Meeting (2013)

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