TY - JOUR
T1 - Crystalline mono- and multilayer self-assemblies of oligothiophenes at the air-water interface
AU - Isz, S.
AU - Weissbuch, I.
AU - Kjær, K.
AU - Bouwman, W.G.
AU - Als-Nielsen, J.
AU - Palacin, S.
AU - Ruaudel-Teixier, A.
AU - Leiserowitz, L.
AU - Lahav, M.
PY - 1997
Y1 - 1997
N2 - The formation of Langmuir monolayers at the air-water interface has long been believed to be limited to amphiphilic molecules containing a hydrophobic chain and a hydrophilic headgroup. Here we report the formation of crystalline mono- and multilayer self-assemblies of oligothiophenes, a class of aromatic nonamphiphilic molecules, self-aggregated at the air-water interface. As model systems we have examined the deposition of quaterthiophene (S-4), quinquethiophene (S-5). and sexithiophene (S-6) from chloroform solutions on the water surface. The structures of the films were determined by surface pressure-area isotherms, by scanning force microscopy (SFM) after transfer of the films onto atomically smooth mica, by cryo-transmission electron microscopy (Cryo-TEM) on vitreous ice, and by grazing incidence synchrotron X-ray diffraction (GID) directly on the water surface. S-4 forms two polymorphic crystalline multilayers. in polymorph alpha, of structure very similar to that of the three-dimensional solid, the molecules are aligned with their long molecular axis tilted by about 23 degrees from the normal to the water surface. In polymorph beta the long molecular axis is perpendicular to the water surface. S-5 self-ageregates at the water surface to form mixtures of monolayers and bilayers of the beta polymorph; S-6 forms primarily crystalline monolayers of both alpha and beta forms. The crystalline assemblies preserve their integrity during transfer from the water surface onto solid supports, The relevance of the present results for the understanding of the early stages of crystal nucleation is presented.
AB - The formation of Langmuir monolayers at the air-water interface has long been believed to be limited to amphiphilic molecules containing a hydrophobic chain and a hydrophilic headgroup. Here we report the formation of crystalline mono- and multilayer self-assemblies of oligothiophenes, a class of aromatic nonamphiphilic molecules, self-aggregated at the air-water interface. As model systems we have examined the deposition of quaterthiophene (S-4), quinquethiophene (S-5). and sexithiophene (S-6) from chloroform solutions on the water surface. The structures of the films were determined by surface pressure-area isotherms, by scanning force microscopy (SFM) after transfer of the films onto atomically smooth mica, by cryo-transmission electron microscopy (Cryo-TEM) on vitreous ice, and by grazing incidence synchrotron X-ray diffraction (GID) directly on the water surface. S-4 forms two polymorphic crystalline multilayers. in polymorph alpha, of structure very similar to that of the three-dimensional solid, the molecules are aligned with their long molecular axis tilted by about 23 degrees from the normal to the water surface. In polymorph beta the long molecular axis is perpendicular to the water surface. S-5 self-ageregates at the water surface to form mixtures of monolayers and bilayers of the beta polymorph; S-6 forms primarily crystalline monolayers of both alpha and beta forms. The crystalline assemblies preserve their integrity during transfer from the water surface onto solid supports, The relevance of the present results for the understanding of the early stages of crystal nucleation is presented.
KW - Nye funktionelle materialer
U2 - 10.1002/chem.19970030615
DO - 10.1002/chem.19970030615
M3 - Journal article
SN - 0947-6539
VL - 3
SP - 930
EP - 939
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
IS - 6
ER -