Dipolar, chromophoric polymers via carbonyldiimidazole-promoted coupling of piperazinyl carboxylic acids.

Two monomers containing N-phenylpiperazine and carboxylic acid groups were synthesized by multistep sequences and isolated by reverse phase extraction. Reaction of the monomers with carbonyldiimidazole gave polyimides whose subunit dipole moments project significantly in a common direction along the polymer backbone. Modification of the polymers increased the expected hyperpolarizabilities and dipole moments, leading to substances potentially useful for second order nonlinear optics.