Synthesis of Novel Amphiphilic Azobenzenes and X-ray Scattering Studies of Their Langmuir Monolayers

TY - JOUR

T1 - Synthesis of Novel Amphiphilic Azobenzenes and X-ray Scattering Studies of Their Langmuir Monolayers

AU - Sørensen, Thomas Just

AU - Kjær, Kristian

AU - Breiby, Dag Werner

AU - Laursen, Bo Wegge

PY - 2008

Y1 - 2008

N2 - We report a simple synthetic route to novel symmetrical alkylated and acylated amphiphilic 4,4‘-diaminoazobenzene dyes, with their optical axis perpendicular to the amphiphilic direction of the molecule. Three different substitution patterns are reported, two of which are highly amphiphilic. At the air-water interface, the amphiphilic azobenzenes form noncrystalline but stable Langmuir films that display an unusual reversible monolayer collapse close to 35 mN/m. The structures and phase transitions were studied by X-ray reflectivity (XR) and grazing-incidence X-ray diffraction, both utilizing synchrotron radiation. Compression beyond the collapse point does not change the XR data, showing that the film is unchanged at the molecular level, even at areas less than half of that of the collapse. This leads to the conclusion that few macroscopic collapse sites are responsible for reversibly removing large amounts of material from the interface.

AB - We report a simple synthetic route to novel symmetrical alkylated and acylated amphiphilic 4,4‘-diaminoazobenzene dyes, with their optical axis perpendicular to the amphiphilic direction of the molecule. Three different substitution patterns are reported, two of which are highly amphiphilic. At the air-water interface, the amphiphilic azobenzenes form noncrystalline but stable Langmuir films that display an unusual reversible monolayer collapse close to 35 mN/m. The structures and phase transitions were studied by X-ray reflectivity (XR) and grazing-incidence X-ray diffraction, both utilizing synchrotron radiation. Compression beyond the collapse point does not change the XR data, showing that the film is unchanged at the molecular level, even at areas less than half of that of the collapse. This leads to the conclusion that few macroscopic collapse sites are responsible for reversibly removing large amounts of material from the interface.

U2 - 10.1021/la703022s

DO - 10.1021/la703022s

M3 - Journal article

SN - 0743-7463

VL - 24

SP - 3223

EP - 3227

JO - Langmuir

JF - Langmuir

IS - 7

ER -