Institute of Physical Energetics, Latvian Academy of Sciences, LV-1006 Riga, Lativa.
Langmuir–Blodgett films of indandione-l,3 pyridinium betaine. II: Molecular structure and properties of monolayers; simulation and optical absorption data
Article first published online: 14 SEP 2004
Copyright © 1994 John Wiley & Sons Ltd.
Advanced Materials for Optics and Electronics
Volume 4, Issue 1, pages 27–41, January/February 1994
How to Cite
Rutkis, M. A., Lindquist, S. E., Wistus, E., Almgren, M., Klimkans, A. B., Larsson, S. and Silinsh, E. A. (1994), Langmuir–Blodgett films of indandione-l,3 pyridinium betaine. II: Molecular structure and properties of monolayers; simulation and optical absorption data. Adv. Mater. Opt. Electron., 4: 27–41. doi: 10.1002/amo.860040105
- Issue published online: 14 SEP 2004
- Article first published online: 14 SEP 2004
- Manuscript Revised: 14 SEP 1993
- Manuscript Received: 2 JUN 1993
- Amphiphilic indandione-1,3 pyridinium betaine derivatives;
- Langmuir–Blodgett monolayers;
- Monolayer spectral characteristics;
- Simulation of molecular structure
The molecular structure and optical properties of a monolayer at the air/water interface of novel amphiphilic derivatives of indandione-1,3 pyridinium betaine (IPB) with different lengths of the aliphatic tail, namely C1lIPB and C17IPB, have been studied using optical absorption techniques and computer simulation approaches.
The compression π-A isotherm of the C17IPB monolayer and computer simulation of its molecular structure show that there may exist two energetically stable molecular configurations, one with antiparallel orientation of the dipole moments of the C17IP ‘heads’ in the low-pressure region at π = 5–32 mN m−1 and the second (after a distinct phase transition at π = 33 mN m−1) with parallel orientation of the dipoles, with different tilt angles and areas per molecule. For C11IPB only the first structural phase is observable.
The compression-induced changes in spectral characteristics of the two structural phases go in diametrically opposite directions. In the low-pressure phase compression induces a red shift and an increase in intensity of the S1 absorption band, while in the high pressure phase a blue shift and a decrease in the intensity of this band are observed. These spectral changes correlate reproducibly with the compression π-A isotherms. Measurements of absorption dichroism confirm the change in the tilt angle at the phase transition pressure. The compression-induced spectral changes have been substantiated by the results of quantum chemical calculations.