Magnetic Properties of a Binary Mixture of Paramagnetic Metallomesogens
- PDF / 1,007,193 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 99 Downloads / 175 Views
an interesting class of magnetic molecules [1]. The molecular geometry and the structure of
molecular condensed phases which could specify magnetic interactions leading to ferro-, antiferro- and ferri-magnetic properties, have been designed and testified so far [2-41. However, it is quite difficult to predict the crystal structure only by the knowledge of molecular structures if one can design the molecular structure possessing an appropriate electronic structure for required magnetic properties. Usually such molecules have rather complicated chemical structure and are tend to show some degree of difficulty on synthesis. On the other hand, it is well known that the molecular orientation could be easily controlled by an external field in mesomorphic phases. Additionally, as one of the novel classes of liquid crystals, metallomesogens have been extensively studied in these two decades and variety of metal complexes containing a paramagnetic metal ion have been evidenced to show mesomorphic properties [5-7]. Mesomorphic states have several characteristics for their properties as molecular aggregations. "Miscibility" between two mesomorphic compounds which mutually show thermodynamically identical liquid crystalline phases is one of the special properties of mesomorphic states. Thus, miscibility may enable us to prepare some magnetic materials consisting of several metallomesogens. Though it is quite reasonable to believe that liquid crystals are not suitable for magnetic materials because of the inefficiency of spin-spin interaction due to the molecular fluctuation, it is considered on one hand to be one concept that mesomorphic states will be utilized as a field in which molecular alignment is controlled forward the required magnetic interaction and often it may be required to be fixed into the solid state. In fact, ferromagnetic interaction
823 Mat. Res. Soc. Symp. Proc. Vol. 488 © 1998 Materials Research Society
a mesogenic tetraphenylporphyrin manganese(III) complex doped with TCNE was recently reported [8]. In this communication, magnetic behavior for a binary mixture consisting of two paramagnetic metallomesogens is reported. In 1987, Kamachi et al. reported ferromagnetic interaction in a polyacrylate possessing tetraphenylporphinatocopper(II) and tetraphenylporphinatooxovanadium(IV) as their pendant groups [9]. In this system, the paramagnetic moieties are sterically forced to stay close together along a polymer chain. In this work, discotic porphyrin metallomesogens, Cu(II) and V=O(IV) complexes of tetradodecylphenylporphyrin (1 and 2, respectively) as shown below and the 1:1 mixture were investigated on the magnetic behavior.
12H25 012H25
C 1 2H25
C 1 2H25
1 M=Cu 2 M=VO 3 M=H 2 5,10,15,20-Tetrakis(4-n-dodecylphenyl)porphyrin (C l2TPPH2, 3) and the metal complexes incorporating metal ions (Co 2 +, Ni 2 +, Cu 2+, Zn 2+ and Pd 2 +), have been reported to exhibit two kinds of lamellar discotic mesophases [10,11]. The results of DSC and X-ray diffraction measurements indicated C I2TPPH2 exhibits two differ
Data Loading...
