|
| << vorige | volgende >> |
Tijdschrift beschrijving
Alle jaargangen van het bijbehorende tijdschrift
Alle afleveringen van het bijbehorende jaargang
Alle artikelen van de bijbehorende aflevering
Details van artikel 8 van 10 gevonden artikelen
| Titel: |
Solubilization and photoreactivity of E-ethyl cinnamate in smectic B mesophases VII. Photoreactions in liquid crystals |
| Auteur: |
Stumpe, J. Grande, S. Wolf, K. Hempel, G. |
| Verschenen in: |
Liquid crystals |
| Paginering: | Jaargang 11 (1992) nr. 2 pagina's 175-198 |
| Jaar: |
1992-02-01 |
| Inhoud: |
The relative quantum yields of (2 + 2) photocycloaddition for E-ethyl 4-methoxycinnamate 1 have been estimated in smectic and nematic phases as well as in isotropic melts of trans, trans-4'-n-butyl- and trans, trans-4'-ethylbicyclohexyl-4-carbonitrile (CCH-4 and CCH-2). The quantum yield is significantly higher in smectic B phases compared to the values in the isotropic and nematic range. The existence of a second smectic phase, S2, of CCH-4 has been shown. The photoreaction does not occur in this mesophase. The solubilization behaviour of deuteriated E-ethyl 4-methoxycinnamate has been studied by means of 2H, 1H, and 13CNMR as well as DSC and thermal microscopy. The cinnamate has a very low solubility in SB phases (< 0·5 wt%) in contrast to the S2 and nematic phases. The results indicate that phase separation occurs to cinnamate-rich nematic or isotropic regions below the bulk smectic B—nematic transition temperature. Thus, the high quantum yields are due to compartmentalization of the cinnamate in nematic or isotropic spheres of the biphasic smectic B—nematic or smectic B—isotropic systems. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 8 van 10 gevonden artikelen
| << vorige | volgende >> |