Molecular J-aggregation for the Langmuir-Blodgett film of a novel tripodal dye

We investigated the arrangement of a tripodal dye. N(1),N(3),N(5)-tris(4-(5-(3,4,5-tridodecyloxyphenyl)-1,3,4-oxadiazol-2-yl)phenyl)benzene-1,3,5-tricarboxamide, A3O-3 (amide linkage), at the air-water interface by the Langmuir-Blodgett technique. The surface pressure (Pi) vs. surface area (A) isotherm for A3O-3 showed a sharp transition at 200 angstrom(2)/molecule. AT-IR and UV-visible spectrophotometry were employed to study the self-assembled structure of A3O-3 multilayers on the substrate. Comparisons with theoretical calculations of the molecular and extrapolated areas of the Pi-A isotherm revealed that a change in the molecular arrangement of the A3O-3 monolayer took place under conditions of sharply increasing surface pressure. AT-IR data showed no hydrogen-bonding at high pressure and also demonstrated that the stability of the monolayer is due to pi-pi interactions. UV data displayed a maximum red shift as the surface pressure increased, which suggests that J-aggregation was initiated at the monolayer interface. (C) 2010 Elsevier B.V. All rights reserved.D.S. would like to acknowledge the Basic Research Program in Korea Research Foundation (KRF) for financial support. This work was partially supported by a grant from Hanyang University (HYU-2010-T)