Ionic Discotic Liquid Crystals: Recent Advances and Applications - Biosensors Nanotechnology - page 305

have been studied by Wu et al. [100]. h ese compounds 67a-o exhibited
Col h phase over a wide range of temperatures (Table 9.14). Increasing the
carbon lengths of the complexes has in all cases a similar ef ect of lower-
ing the clearing points and decreasing the mesophase range. h e clearing
temperatures decreased in the order Ni > Pd > Cu, this decrease being due
to the dif erent size of the metal cations. Compared with metal-free deriva-
tives, Cu complexes have lower clearing temperatures by 55-67 C, while
Ni complexes have 21-27 C higher temperatures. Complexes with shorter
alkyl chains were room temperature liquid crystalline.
Bischelate ionic silver complexes 68a-d were prepared by complexation
of chiral 4,4'-dialkoxy-2,2'-bipyridine with Ag(I). Compounds contain-
ing OTf and DOS anions only displayed Col h phase (Table 9.15). However,

Table 9.14 Phase behavior of transition metal complexes of Ni, Cu and
Pd derived from tetrabenzotetraazacyclohexadecine.

Compound M n Phase transition behavior

67a Cu 10 Col h 196 I

67b Cu 12 Col h 193 I

67c Cu 14 Cr 26 Col h 190 I

67d Cu 16 Cr 58 Col h 195 I

67e Cu 18 Cr 66 Col h 183 I

67f Ni 10 Col h 290 I

67g Ni 12 Col h 270 I

67h Ni 14 Cr 28 Col h 265 I

67i Ni 16 Cr 59 Col h 238 I

67j Ni 18 Cr 51 Col h 234 I

67k Pd 10 Col h 261 I

67l Pd 12 Col h 250 I

67m Pd 14 Col h 238 I

67n Pd 16 Cr 42 Col h 224 I

67o Pd 18 Cr 49 Col h 201 I