Synthesis and characterization of naphthalene diimide/diethynylbenzene copolymers

A series of conjugated polymers has been synthesized by Sonogashira coupling of N,N'-bis(2octyldodecyl)-2,6-dibromonaphthalene-1,4,5,8-bis(dicarboximide) and four para-diethynylbenzene derivatives: 1,4-diethyny1-2,5-dihexadecyloxybenzene, 1,4-diethyny1-2,5-bis(2-octyldodecyloxy) benzene, 1,4-bis(2-ethylhexyl)-2,5-diethynylbenzene, 1,4-diethyny1-2,5-bis(trifluoromethyl)benzene. The polymers display absorption maxima at wavelengths ranging from 530 nm to 654 nm with molar absorptivities ranging from ca. 4 to 7 x 10(4) M-1 cm(-1). The peak reduction potentials, determined by differential pulse voltammetry, for polymer films varied from -0.93 to -1.14 V vs. ferrocenium/ferrocene with the trifluoromethyl-substituted derivative being the most readily reduced. All four polymers exhibited electron transport characteristics in bottom-gate/top-contact field-effect transistors, showing average electron mobility values ranging from 1.4 x 10(-4) to 3.7 x 10(-3) cm(2) V-1 s(-1). (C) 2012 Elsevier Ltd. All rights reserved.