Electronically Excited States of Closed-Shell, Cyano-Functionalized Polycyclic Aromatic Hydrocarbon Anions

Few anions exhibit electronically excited states, and, if they do, the one or two possible excitations typically transpire beyond visible spectrum into near-infrared. These few, red-shifted electronic absorption features make tantalizing candidates as carriers of diffuse interstellar bands (DIBs), a series mostly unknown, astronomically ubiquitous documented for over century. The recent detection benzonitrile implies that cyano-functionalized polycyclic aromatic hydrocarbon (PAH) may be present in space. presently reported quantum chemical work explores properties deprotonated benzene, naphthalene, and anthracene functionalized with single cyano group. Both emission states are explored. findings show larger energies possess both valence dipole bound 450–900 nm range oscillator strengths types >1×10−4. state transitions will produce slightly altered substructure from another making them appear to originate different molecules. known presence related molecules, differing natures each, wavelength peaks these PAH coincident DIB properties. Finally, methods utilized able predict dipole-bound within 1.0 meV window relative electron binding energy.