“…Polarized Spectroscopic Measurements. The orientation of the components (the cinnamate and surfactant ammonium ions) in the solid films was determined by measuring the polarized absorption spectra of the molecular self-assembled films in UV−vis and IR regions. − UV and IR spectroscopic absorbances are proportionally dependent on the squared optical transition moments of the components, which can be obtained from irradiation at the appropriate incident wavelength and from the transition moments. Here, the optical transition moments are closely related to the average values of the molecular dipole moments in the electric field of the incident light.…”
Section: Resultsmentioning
confidence: 99%
“…As an alternative method, a study of the 1D electron density distribution could be applied to the characterization of the self-assembled stacking structure of the solid films along the c -axis by means of small-angle X-ray diffraction investigations . In this contribution, we report on the E − Z photoisomerization of solid films made of 1:1 ion pairs of dioctadecyldimethylammonium/cinnamate ions (C18 trans- cin) on glass slides and discuss the relationship between the photoreactivities and conformational structures of the films using X-ray diffraction analysis and polarized spectroscopic techniques (see Chart ). − 1 C18 trans- cin and C18 cis -cin …”
UV illumination of dioctadecyldimethylammonium cinnamates (C18 trans-cin and C18 cis-cin) was found to result in the E-Z photoisomerization of the cinnamate moieties in self-assembling multilamella films. In the present case, a common photostationary state (pss), which can usually be observed in solution, was not seen in the photolysis of the self-assembled material films of C18 trans-cin and C18 cis-cin having a bimolecular (bilayer)-unit lamellar structure. Both the E-and Z-isomers are difficult to isomerize and exhibit different E/Z ratios, 73:27 and 10:90, respectively, even under prolonged UV irradiation. However, the same E/Z ratio (15:85) could be attained at the pss from either isomer in a monolayer-unit structure. The E/Z ratios were found to change abruptly upon heat treatment at around 55 °C before photoisomerization, implying a thermal structural change in the films. Analysis of X-ray diffraction, differential scanning calorimetry, and polarized IR and UV-vis spectroscopic investigations have indicated that the solid films have a characteristic multilamellar structure consisting of bilayer units when they are cast on the silica glass without heat treatment above 55 °C. Moreover, the solid films preheated to 80 °C were composed of an interdigitated monolayer unit having a loose packing structure. This result is in contrast to the bilayer-unit structure of the solid films where E-Z photoisomerization of both isomers is suppressed.
“…Polarized Spectroscopic Measurements. The orientation of the components (the cinnamate and surfactant ammonium ions) in the solid films was determined by measuring the polarized absorption spectra of the molecular self-assembled films in UV−vis and IR regions. − UV and IR spectroscopic absorbances are proportionally dependent on the squared optical transition moments of the components, which can be obtained from irradiation at the appropriate incident wavelength and from the transition moments. Here, the optical transition moments are closely related to the average values of the molecular dipole moments in the electric field of the incident light.…”
Section: Resultsmentioning
confidence: 99%
“…As an alternative method, a study of the 1D electron density distribution could be applied to the characterization of the self-assembled stacking structure of the solid films along the c -axis by means of small-angle X-ray diffraction investigations . In this contribution, we report on the E − Z photoisomerization of solid films made of 1:1 ion pairs of dioctadecyldimethylammonium/cinnamate ions (C18 trans- cin) on glass slides and discuss the relationship between the photoreactivities and conformational structures of the films using X-ray diffraction analysis and polarized spectroscopic techniques (see Chart ). − 1 C18 trans- cin and C18 cis -cin …”
UV illumination of dioctadecyldimethylammonium cinnamates (C18 trans-cin and C18 cis-cin) was found to result in the E-Z photoisomerization of the cinnamate moieties in self-assembling multilamella films. In the present case, a common photostationary state (pss), which can usually be observed in solution, was not seen in the photolysis of the self-assembled material films of C18 trans-cin and C18 cis-cin having a bimolecular (bilayer)-unit lamellar structure. Both the E-and Z-isomers are difficult to isomerize and exhibit different E/Z ratios, 73:27 and 10:90, respectively, even under prolonged UV irradiation. However, the same E/Z ratio (15:85) could be attained at the pss from either isomer in a monolayer-unit structure. The E/Z ratios were found to change abruptly upon heat treatment at around 55 °C before photoisomerization, implying a thermal structural change in the films. Analysis of X-ray diffraction, differential scanning calorimetry, and polarized IR and UV-vis spectroscopic investigations have indicated that the solid films have a characteristic multilamellar structure consisting of bilayer units when they are cast on the silica glass without heat treatment above 55 °C. Moreover, the solid films preheated to 80 °C were composed of an interdigitated monolayer unit having a loose packing structure. This result is in contrast to the bilayer-unit structure of the solid films where E-Z photoisomerization of both isomers is suppressed.
Eine parallele Anordnung und nicht eine senkrechte Anordnung der aromatischen Verbindung bezüglich des Tensidmoleküls (siehe schematische Darstellung) wird bei der Bildung von Liposomenstrukturen bevorzugt, da so die Hydrophilie des Aggregats verringert wird. Dies ergaben Untersuchungen mit den kristallinen Komplexen aus Monoalkylammoniumhalogeniden und verschiedenen aromatischen Verbindungen.
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