Pyrimido[4,5-g]quinazoline-4,9-dione as a new building block for constructing polymer semiconductors with high sensitivity to acids and hole transport performance in organic thin film transistors

Pyrimido[4,5-g]quinazoline-4,9-dione (PQ) was used for the first time as a building block for pi-conjugated polymer semiconductors. Copolymers of PQ and bithiophene showed dramatic bathochromic shifts in their absorption spectra in the presence of protonic (acetic acid and trifluoroacetic acid) and Lewis (BBr3) acids, resulting from the strong interaction of the basic 1,6-nitrogen atoms in the PQ unit with the acid. These polymers exhibited characteristic p-type semiconductor performance with hole mobilities of up to 6.4 x 10(-3) cm(2) V-1 s(-1) in organic thin-film transistors (OTFTs). The potential bioactivity, high sensitivity to acids, and good field effect transistor performance of these PQ-based polymers will enable their application for bio- and chemo-sensors.