Band gap control in conjugated oligomers via Lewis acids.
A simple and effective strategy for optical band gap control is demonstrated through the use of a novel small acceptor/donor/acceptor molecule, 1, and group-13 Lewis acids. Chromophore 1 contains a dithienolesilole donor unit end-capped with benzo-2,1,3-thiadiazole (BT) acceptor units. Addition to 1 of stoichiometeric quantities of Lewis acids of varying strength resulted in the formation of Lewis adducts with progressively red-shifted primary charge-transfer absorption bands. These complexes have absorption spectra that approach those of known conjugated copolymers containing related units. NMR spectroscopy and X-ray diffraction studies revealed that 1 binds 2 equiv of Lewis acid via the nitrogen at the 3-position of BT.
Welch
Gregory C
GC
Center for Polymers and Organic Solids, Department of Chemistry & Biochemistry, University of California, Santa Barbara, California 93106, USA.
Coffin
Robert
R
Peet
Jeff
J
Bazan
Guillermo C
GC