Systematical study on electronic properties of monoazaphenanthrene compounds

Abstract Phenanthrene, the smallest phenacene molecule, has attracted attention since its discovery more than a century ago. Its mono-aza derivatives are also historical compounds and the best candidates for examining the effect of nitrogen atoms on the electronic structure. We used density functional theory to investigate the electronic properties of phenanthrene and a series of its mono-aza derivatives. The two low-lying ππ* excited states of phenanthrene are discussed on the basis of the Lb and La states under Platt’s nomenclature. Upon cursory inspection, similar assignments appeared to apply to the excited states of the monoazaphenanthrene compounds; however, the transition dipole moment indicated that simple assignments could not be applied to these compounds. Of the five mono-aza derivatives, benz[f]isoquinoline was an exception, and simple assignments could be applied.