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Monolayer and Bilayer Stability of Ammonium Amphiphiles Carrying an Azobenzene Unit – Effects of Substituents at the Azobenzene Unit by Marcel D. Everaars; Antonius T. M. Marcelis; Ernst J. R. Sudhölter is a Chemistry article available to read on EtoBox.

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## Abstract Novel double‐chained ammonium amphiphiles carrying one azobenzene moiety (I) have been synthesized. The bilayer‐stabilizing effect of different azobenzenes (ABs) has been investigated by measuring the “gel‐to‐liquid crystalline” phase transition temperatures of the formed bilayers in water using differential scanning calorimetry. It is found that the stabilizing effect of the azobenzenes strongly depends on the substituents at the aromatic ring. The stabilizing effect increases in the sequence F < H < NO~2~ < CN < OCH~3~ < N=N–Ph, which cannot be correlated with the electron‐withdrawing or ‐donating properties of the substituents. It is concluded that dipole‐dipole interactions between the ABs are of minor importance for the overall stabilization of the bilayer. Instead, other factors determine the strength of the van der Waals interactions between the ABs. In the bilayers the ABs form H‐aggregates as is observed by the blue shift of the UV absorption maximum. This blue shift is not affected by the “gel‐to‐liquid crystalline” phase transition. Bilayers of I–N=N–Ph do not exchange monomers with vesicles of didodecyldimethylammonium bromide, whereas all other investigated

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Author

Marcel D. Everaars; Antonius T. M. Marcelis; Ernst J. R. Sudhölter

Publisher

John Wiley and Sons; Wiley (John Wiley & Sons); VCH Verlagsgesellschaft; Wiley (ISSN 0947-3440)

Published

1997

Language

EN

Field

Chemistry (Physical Sciences)