Perepichka, D.F., Bryce, M.R., Batsanov, A.S., Howard, J.A.K., Cuello, A.O., Gray, M., Rotello, V.M., "Trialkyltetrathiafulvalene-sigma-tetracyanoanthraquinodimethane (R3TTF-sigma-TCNAQ) diads: Synthesis, intramolecular charge- transfer properties, and X-ray crystal structure", Journal of Organic Chemistry, 2001