Control of Porphyrin Orientation in Thermotropic Liquid Crystals by Molecular Design. A Time-Resolved EPR Study

Shalom Michaeli, Muhamad Hugerat, Haim Levanon, Mazal Bernitz, Aliza Natt, Ronny Neumann

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Molecular compatibility of a guest porphyrin in a thermotropic nematic liquid crystalline host phase was shown to control the orientation of the porphyrin chromophore. In this manner, the normal alignment of a porphyrin plane parallel to the director in a nematic phase was inverted to a perpendicular orientation by attachment of mesogenic type appendages orthogonal to a porphyrin ring on one side of the ring plane. This molecular design also leads to a head-to-tail ordering of the porphyrin even in isotropic phases. The conclusions reached are based on detection and analysis of time-resolved EPR spectra of photoexcited triplet states.

Original languageEnglish (US)
Pages (from-to)3612-3618
Number of pages7
JournalJournal of the American Chemical Society
Volume114
Issue number10
DOIs
StatePublished - May 1 1992

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