EFFECT OF ELONGATION OF THE PI-ELECTRON SYSTEM ON THE BEHAVIOR OF AMPHIPHILES CONTAINING THE PYRAZINE RING

The amphiphile 1b, with a diacetylenic linkage between two aromatic rings of 5-(p-dodecyloxyphenyl)pyrazine-2-carboxylic acid 1a, and the diacetylene homologue 2b of 4'-dodecyloxybiphenyl-4-carboxylic acid 2a were newly synthesized. The amphiphile 1b formed an expanded but stable monolayer at the air-water interface, whereas 2b did not form a monolayer. The Langmuir-Blodgett (LB) film obtained by deposition of the monolayer of 1b was shown to be J-aggregates, making a large contrast to the H-aggregates of the LB film of 1a. The different behaviors of 1a and 1b were explained in terms of electrostatic multipole-multipole interaction between the chromophores in the layered molecular arrangement.