6533b821fe1ef96bd127b6d9
RESEARCH PRODUCT
Photophysical Properties of Discotic Dibenzopyrenes
Pawel UznanskiDimitra MarkovitsiSylvie MarguetHelmut RingsdorfPeter Schuhmachersubject
Phase transitionCrystallographyAbsorption spectroscopyLiquid crystalChemistrySide chainOrganic chemistryMesophaseAbsorption (chemistry)Condensed Matter PhysicsSupercoolingOptical bistabilitydescription
Abstract The photophysical properties of three discogenic dibenzopyrenes substituted by eight pentyloxy (O5DPB), heptyloxy (O7DBPP) or decyloxy (O10DBP) side chains are studied in solution and thin films. It is shown that the absorption and fluorescence spectra of the columnar mesophases are clearly distinguishable from those of the corresponding crystalline phases, allowing the study of phase transitions. Thus, it is found that the shorter the lateral chain length, the slower the crystallisation process. For O5DBP, the supercooled mesophase is stable over a period of at least one year; it crystallises after cooling below the glassy transition. Such a behaviour gives rise to temperature controlled optical bistability based on the position of the lowest energy absorption band and illustrated by a hysterisis loop.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1997-02-01 | Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals |