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

Abstract

The 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(È), 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(È) 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.

Uniaxially Oriented, Highly Ordered, Large Area Columnar Superstructures of Discotic Supramolecules using Magnetic Field and Surface Interactions

“…[ 27] For octadecyltrichlorosilane (OTS) functionalization of Si wafer, cleaning processes were performed by 30 min sonication in 2:1 (v/v) H 2 SO 4 /H 2 O 2 , acetone, ethanol and deionized water sequentially. A cleaned Si wafer was soaked in a 4 mg mL À1 solution of OTS (90þ%, Aldrich) in toluene (Merck) and rinsed with toluene.…”

Discotic Liquid Crystals

“…Lee et al studied Co complexes of symmetrical octa­(thioalkyl)­azaporphyrins 219 with Col h phases (Scheme ) and found magnetic uniaxial alignment of the columnar superstructure over a centimeter length scale via SANS measurements. , Searching for push–pull systems, which are suitable for NLO applications, Belviso et al envisaged nonsymmetrical aryl-substituted octa­(thioalkyl)­azaporphyrins 220 (Scheme ). , …”

“…454 Triply fused metalloporphyrin dimers 217 with peripheral alkoxy and oligoethylenglycol side chains (Scheme 96) were described by Sakurai et al 455 and found magnetic uniaxial alignment of the columnar superstructure over a centimeter length scale via SANS measurements. 116,457 Searching for push−pull systems, which are suitable for NLO applications, Belviso et al envisaged nonsymmetrical aryl-substituted octa(thioalkyl)azaporphyrins 220 (Scheme 97). 458,459 A series of derivatives 220 were prepared which assembled into Col h phases.…”

Synthesis and research of a kind of perylene imide discoid molecule

“…This can make the molecules oriented, which is also a means to change the direction of the molecules [7][8][9] . What is more, Zone-Melting [10] , LB deposition [11][12][13][14] , Substrate surface treatment, IR irradiation [15][16] , magnetic [17][18] , blends. However, the use of these methods has certain limitations, and many factors need to be considered such as the solubility of the compound, the type of sacrificial layer, and the thermal stability (whether the molecular thermal temperature is higher than the liquid crystal interval).…”