Ligands coordinated to metal complexes play a central role in dictating the electronic properties of these complexes. We are interested in studying pH-dependent ligands to determine how protonation state changes affect these electronic properties. Altering electronic properties in a controlled manner could lead to the development of catalysts that can be tuned or switched on and off through relatively simple changes in external environment. To this end, we report on several ruthenium complexes with the 4'-hydroxy-2,2':6',2''-terpyridine (tpyOH) and 4'-(4-hydroxyphenyl)-2,2':6',2''-terpyridine (tpyPhOH) ligands containing hydroxyl functional groups. Cyclic voltammetry as a function of pH using a Britton-Robinson buffering system was utilized to develop Pourbaix Diagrams of the complexes [Ru(tpy)(tpyOH)]2+, [Ru(tpyOH)2]2+, [Ru(tpy)(tpyPhOH)]2+, and [Ru(tpyPhOH)2]2+(tpy = 2,2':6',2''-terpyridine). This series of complexes gives an analysis of both quantity of hydroxyl groups and spacing in the terpyridine ring. In the tpyOH ligand, the hydroxyl group is attached directly to the terpyridine ring, while in the tpyPhOH complex, the hydroxyl group is further separated by a phenyl ring, which can rotate out of plane with the terpyridine ring, disrupting conjugation. Computational analysis of structure and electronics of these complexes will also be reported.

Electrochemical properties of hydroxyl-substituted terpyridine complexes as a function of pH

2019 Spring National Meeting

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