  Ubiquitous unidentified infrared emission bands are seen in many astronomical
sources. Although these bands are widely, if not unanimously, attributed to the
collective emission from polycyclic aromatic hydrocarbons, no single species
from this class has been detected in space. We present the discovery of two -CN
functionalized polycyclic aromatic hydrocarbons, 1- and 2-cyanonaphthalene, in
the interstellar medium aided by spectral matched filtering. Using radio
observations with the Green Bank Telescope, we observe both bi-cyclic ring
molecules in the molecular cloud TMC-1. We discuss potential in situ gas-phase
formation pathways from smaller organic precursor molecules.
