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Nitrogen containing heterocyclic compounds with red-ox properties, photovoltaic behavior, and chelating abilities are of interest for materials applications.  In this context, we have been working with fused-ring quinoliziniums 1, verdazyls 2, and 2-azinylbenzo[1,2,3]triazoles 3.

We have developed a practical method for the preparation of benzo[c]quinolizinium (1a), pyrido[1,2-c]benzo[d][1,2,4]triazinium (1b), pyrido[2,1-c][1,2,4]benzotriazin-11-ium (1c), and pyrido[1,2-a]quinoxalin-11-ium (1d) by Ca²⁺–assisted cyclization of the corresponding fluoro pyridines. All four ions have been investigated for their structural, spectroscopic, and electrochemical properties, and experimental data was augmented with DFT quantum-mechanical calculations.  The new method permitted the preparation of derivatives of pyrido[1,2-c]benzo[d][1,2,4]triazinium (1b) such as those with fluoro, methyl, and hydroxymethyl substituents, suitable for further fuctionalization of this heterocyclic cation, and tuning of the photophysical and red-ox properties of more complex molecular systems.

We also investigated functional group transformations in verdazyls of the general structure 2 as means to build more complex molecular systems and to control morphology of the solid.

We have also prepared several novel 2-azinylbenzo[1,2,3]triazoles as bidentate ligands for mono- and polynuclear metal complexes. One of the new compounds, 2-(2-pyridyl)benzo[1,2,3]triazole (3a), was used to prepare (bpy)₂(3a)Ru²⁺ complex which was characterized by structural, spectroscopic and electrochemical methods. The new complex has a lower bandgap than (bpy)₃Ru²⁺ which provides more flexibility in designing compounds with desired optical properties in the visible portion of the spectrum.

These results have been presented at ACS meetings and are described in four upcoming journal publications.