THERMOTROPIC PHASE-TRANSITIONS IN 5,15-BIS(4-ALKOXYPHENYL)OCTAALKYLPORPHYRINS

Citation
Ejr. Sudholter et al., THERMOTROPIC PHASE-TRANSITIONS IN 5,15-BIS(4-ALKOXYPHENYL)OCTAALKYLPORPHYRINS, Journal of materials chemistry, 6(3), 1996, pp. 357-363
Citations number
29
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry Physical","Material Science
ISSN journal
0959-9428
Volume
6
Issue
3
Year of publication
1996
Pages
357 - 363
Database
ISI
SICI code
0959-9428(1996)6:3<357:TPI5>2.0.ZU;2-U
Abstract
Nineteen novel alkyl substituted porphyrins have been synthesized and their thermal phase behaviour has been investigated in detail. Twelve compounds showed a reversible phase transition below the isotropizatio n temperature. From time resolved microwave conductivity (TRMC) measur ements and powder X-ray diffractometry it was concluded that the molec ular packing does not change significantly at the lower phase transiti on temperature and that the porphyrin cores occupy isolated positions. Single X-ray diffraction measurements showed that the porphyrins are arranged in a layered structure and that the space between the layers is occupied by the alkyl substituents of the pyrrole units. The phase transitions at the lower temperature were therefore identified as chan ges in the crystal ordering of the porphyrins.