UNUSUALLY LOW-ENERGY ELECTRONIC-TRANSITIONS IN POLY(DIACETYLENE) SOLUTIONS - SOLVATOCHROMIC AND THERMOCHROMIC BEHAVIOR OF POLY(1,4-BIS(3-QUINOLYL)BUTA-1,3-DIYNE)

Solutions of poly(1,4-bis(3-quinolyl)buta-1,3-diyne) (PDQ) have shown the lowest energy electronic transitions of all the reported poly(diac etylene)s. Unusual solvato- and thermochromic behavior of PDQ in vario us polar and nonpolar environments is discussed. The role of hydrogen bonding appears crucial to the solution and chromic behavior in these solutions. pi-Conjugation between the polymer backbone and the cross-c onjugated heteroaromatic side groups appears to lead to chain segments with unusually extensive electron delocalization. Stable (over a peri od of 2 years), dark green, true solutions in phenol-acetonitrile (non solvent) (lambda(max) = 733 nm) are obtained. The stability of charged and rigid rod-like PDQ macromolecules is explained in terms of screen ing of interchain Coulombic interactions.