Formation of nanoscale aggregates of a coumarin derivative in Langmuir–Blodgett film
- 272 Downloads
In the present communication, we report the formation of organized nanoscale aggregates of a coumarin derivative 7 Hydroxy-N-Octadecyl Coumarin-3-Carboxamide (7HNO3C) at the air–water interface and in Langmuir–Blodgett (LB) films in the presence and absence of stearic acid (SA). A pressure-area isotherm reveals that the 7HNO3C form stable monolayer at the air–water interface. However, the stability can be improved by mixing it with a fatty acid stearic acid (SA). The miscibility study shows that the nature of interaction is strongly dependent on the mixing ratio and surface pressure. At a mole fraction of 0.4 of 7HNO3C in SA, the attractive and repulsive interaction between these two molecules balance each other forming a stable film with nanoscale aggregates. UV-Vis absorption spectroscopic studies reveal the nature of the aggregates in LB films. Scanning electron microscopy gives compelling visual evidence of formation of nanoscale aggregates in the mixed LB films.
KeywordsMole Fraction Coumarin Stearic Acid Water Interface Repulsive Interaction
The author SAH is grateful to DST, CSIR, and DAE for financial support to carry out this research work through DST Fast-Track project Ref. No. SE/FTP/PS-54/2007, CSIR project Ref. 03(1146)/09/EMR-II, and DAE Young Scientist Research Award (No. 2009/20/37/8/BRNS/3328).
- 4.G.G. Roberts, Langmuir–Blodgett Films (Plenum, New York, 1990) Google Scholar
- 5.A. Ulman, An Introduction to Ultrathin Organic Films: From Langmuir–Blodgett Films to Self-Assemblies (Academic Press, New York, 1991) Google Scholar
- 12.S.G. Rautian, I.I. Sobelman, Opt. Spektrosk. 10, 134 (1961). Also in Opt. Spectrosc. 10, 65 (1967) Google Scholar
- 28.C.W. Sheu, C.H. Chang, Y.L. Lee, Y.M. Yang, J.R. Maa, J. Chin. Inst. Chem. Eng. 33, 573 (2002) Google Scholar
- 38.G.L. Gaines Jr., Insoluble Monolayers at the Liquid-Gas Interfaces (Willey, New York, 1966) Google Scholar
- 39.K.S. Birdi, Lipid and Bipolymer Monolayers at Liquid Interface (Plenum, New York, 1966) Google Scholar
- 44.A.K. Dutta, T.N. Misra, A.J. Pal, Langmuir 12, 359 (1996) Google Scholar