Effects of side-chain length on the magnetic response of discotic metallomesogens

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dc.contributor.authorLee, Ji-Hwan-
dc.contributor.authorKim, Hyo-Sik-
dc.contributor.authorPate, Brian D.-
dc.contributor.authorChoi, Sung-Min-
dc.date.accessioned2009-09-16T07:03:38Z-
dc.date.available2009-09-16T07:03:38Z-
dc.date.issued2007-04-01-
dc.identifier.citationJournal of Applied Crystallography, Vol 40, Suppl 1, pp.s68-s72en
dc.identifier.issn0021-8898-
dc.identifier.urihttp://hdl.handle.net/10203/11251-
dc.description.abstractThe magnetic responses of columnar superstructures of discotic metallomesogens with different alkyl side-chain lengths, cobalt octa(n-alkylthio)porphyrazine (CoSx, where x is the peripheral n-alkyl chain length, x = 10, 12, 14), have been investigated by small-angle neutron scattering (SANS). CoSx (x = 10, 12, 14) were heated to their isotropic phases and cooled down to their columnar mesophases under various external magnetic fields (0.2-1.1 T) and the orientational orderings of the columnar mesophases were measured by SANS. The SANS patterns showed clear anisotropies indicating the alignment of columnar domains with their columnar directors perpendicular to the applied magnetic field. The annularly averaged SANS data, I(), of CoSx (x = 10, 12, 14) under various magnetic field strengths were fitted with Lorentzian functions. The full width at half maximum (FWHM) of the I() of CoS10 and CoS12 rapidly decreases with increasing applied magnetic field and then saturates to about 42° at ~0.5 T and 50° at ~0.6 T, respectively. In the case of CoS14, however, the diffraction anisotropy was very weak even at field strengths as high as 1.13 T and the FWHM was very broad, ca. 120°. The dramatic decrease of magnetic field sensitivity of CoS14 may be attributed to the entropy increase with the side-chain length.en
dc.description.sponsorshipThis work was supported by the program of the Basic Atomic Energy Research Institute (BAERI) and the cold neutron research facility development project which are part of the Nuclear R&D Programs funded by the Ministry of Science & Technology (MOST) of Korea. H.-S. Kim is partially supported by the Brain Korea 21 program. We thank the HANARO at KAERI for SANS beamtime support. Part of the SANS measurements utilized the NIST facilities supported in part by the National Science Foundation under DMR- 9986442.en
dc.language.isoen_USen
dc.publisherInternational Union of Crystallographyen
dc.subjectdiscotic metallomesogenen
dc.subjectcolumnar superstructureen
dc.subjectmagnetic alignmenten
dc.subjectsmall-angle neutron scatteringen
dc.subjectchain lengthen
dc.titleEffects of side-chain length on the magnetic response of discotic metallomesogensen
dc.typeArticleen

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