D-luciferin, the luminescent material of firefly, forms charge transfer complexes with organic acceptors such as TCNQ, TCNE, chloranil, DDQ, and iodine. The infrared spectra reveal indirect allowed transition across a single particle gap in the IR range and guassian background absorption. TCNE complex shows triangular distribution due to imperfect nesting. Chloranil complex shows oscillations in the density of states without much dampingthe.