Preparation of New Main-Chain Type Polyanthraquinones. Chemical Reactivity, Packing Structure, Piezochromism, Conductivity, and Liquid Crystalline and Photonic Properties of the Polymers

Poly(5,8-dialkoxyanthraquinone-1,4-diyl) P(5,8-OR-1,4-AQ) (R = n-C6H13 through n-C16H33), poly(5,8-dihydroxyanthraquinone-1,4-diyl) P(5,8-OH-1,4-AQ), poly(4,8-diaminoanthraquinone-1,5-diyl) P(4,8-NH2-1,5-AQ), poly(4,8- dihydroxyanthraquinone-1,5-diyl) P(4,8-OH-1,5-AQ), and poly(4,8-dinitroanthraquinone- 1,5-diyl) P(4,8-NO2-1,5-AQ) were prepared by dehalogenative polycondensation of the corresponding dichloro monomers with a zerovalent nickel complex or copper. They were soluble in organic solvents, and showed number average molecular weights of 3100−8600 and [η] values of 0.10−0.70 dL g-1. P(5,8-OR-1,4-AQ)s and P(4,8-NO2-1,5-AQ) afforded clear XRD peaks and their packing structures in the solid have been analyzed. P(5,8-OR-1,4-AQ) is considered to take an end-to-end packing mode and this polymer with long alkoxy side chains exhibits smectic and enanthiotropic liquid crystalline behavior and piezochromism. All the polymers were susceptible to electrochemical reduction and a linear correlation held between the reduction potentials of the polymers and electron affinity of the corresponding monomeric anthraquinones with a slope of 0.79. A photovoltaic cell using P(4,8-NO2-1,5-AQ) and polythiophene has been constructed.