Synthesis, vapor growth, polymerization, and characterization of thin films of novel diacetylene derivatives of pyrrole. The use of computer modeling to predict chemical and optical properties of these diacetylenes and poly(diacetylenes)

Article abstract of DOI:10.1021/ja00035a013

In the present work two diacetylene derivatives of pyrrole (compounds 1 and 2), which are predicted by semiempirical AMI calculations to have very different properties, are synthesized; the polymerizability of these diacetylenes in the solid state is determined; and the results are compared to the computer predictions. Diacetylene 1 is novel in that the monomer is a liquid at room temperature; this may allow for the possibility of polymerization in the liquid state as well as the solid state. Thin poly(diacetylene) films are obtained from compound 1 by growing films of the monomer using vapor deposition and polymerizing with UV light; these films are then characterized. Interestingly, while the poly(diacetylene) from 1 does not possess good nonlinear optical properties, the monomer exhibits very good third-order nonlinear optical effects (e.g., phase conjugation) in solution. Dilute acetone solutions of the monomer 1 give intensity-dependent refractive indices (η₂) on the order of 10^-6 esu (x⁽³⁾ values on the order of 10^-7 esu); these are 10⁶ times better than for CS₂.