Discotic mesomorphism of 2,3,7,8,12,13,17,18-octakis (alkyl-thio) 5,10,15,20 tetraaza porphyrin and its complexes with some divalent transition metal ions Synthesis and characterization

Abstract

New discotic metallomesogens of 2,3,7,8,12,13,17,18-octakis (alkyl-thio) 5,10,15,20 tetraaza porphyrin (H2Pn) and some related complexes, obtained by reaction of first row transition metal ions Ni(II), Co(II), Cu(II), Zn(II) with the free porphyrin, have been prepared. All materials were characterized by DSC measurements and optical observations. The microscopic structure of all mesophases was checked and characterized by X-ray diffraction. Except for H2P(7–12), all of the compounds are mesogenic; a few of them exhibit mesomorphic polymorphism. Melting (C→D) temperatures range from 40 to 85°C. Only NiP4, CoP4 and CuP4 show higher values. Both temperature and ΔH of isotropization (D→I) show a regular trend with respect to the number of carbon atoms in the alkyl chains and of the nature of the metal. ΔH values for complexes with partially filled d-shell metals are very similar and show definite differences with respect to those of Zn(II). Optical and X-ray data in the case of n 7 indicate a columnar mesophase with hexagonal packing whereas in complexes with n < 7 the observed mesophase shows a non-hexagonal columnar packing. CuP6 and NiP6 probably show both mesophases which are connected by a phase transition, presumably of second order or with exceedingly low enthalpy change but easily detected by polarizing microscopy because of sharp texture changes. As expected, no odd–even effect is detectable on the properties of the liquid-crystalline phases as a function of the number of carbon atoms in the aliphatic chains

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

“…The transition temperatures measured using DSC instruments with a scanning rate of 10 K min À1 are summarized in Table 2. The transition temperatures determined from the different techniques were consistent within a few K. They are also consistent with previous studies (Lelj et al, 1992). Some degree of fluidity in the LC phase of a discotic mesogen at room temperature leads to selfhealing ability after columnar formation (Simpson et al, 2004).…”

“…Cobalt 2, 3,7,8,12,13,17,18-octa(n-alkylthio)porphyrazine (n-alkyl = C x H 2x+1, x = 10) was synthesized in-house and CoS12 and CoS14 were purchased from INNO BioSystem, which utilizes an analog of the synthetic procedure which is described elsewhere (Lelj et al, 1992;Doppelt & Huille, 1990). …”

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

“…[25,26] Phase transition temperatures of CoS10 were determined by differential scanning calorimetry (DSC), using a TA Instruments DSC 2010 at a rate of 10 8C min À1 under nitrogen atmosphere. The transition temperatures of CoS10 were consistent with previous work.…”

Synthesis and characterization of octakis-(9-anthracenylmethylthio) substituted novel porphyrazines

“…Starting with the high-yield route to octakis (alkylthio) porphyrazines by Hoffman [11], an extensive series of derivatives with chemical and physical properties comparable to those of tetrapyrroles have been synthesized [12,13]. The presence of soft S donor atoms in porphyrazines plays an important role in affecting the solid state interactions [14][15][16].…”