C O M M U N I C A T I O N S
Table 1. Phase Transition Temperatures and Enthalpies (in
Parentheses) for 1a-1c Determined by DSC or POMa
Similar alkali-metal-ion-induced phase transformation of triph-
enylenes from a ND phase to a Colh phase was also triggered by
addition of NaOTf (entry 3 in Table 1). The counterions play an
important role in these transformations since lithium chloride was
an ineffective additive for this purpose (entry 4 in Table 1). In this
case, only a minor portion of the salts might be transformed to a
columnar mesophase as indicated by its XRD pattern. However, a
majority of them remained as the ND phase since only the ND phase
was observed by POM for the lithium salt of 1a with up to 12
molar equiv molar of LiCl. This is a remarkable counterion selective
transformation from a ND phase to a Colh phase.
In summary, triphenylene derivatives possessing PEO as side
chains exhibited ND phases at room temperature. Unique phase
transformation from a ND phase to a Colh phase was observed when
alkali metal ions were added. This transformation was dependent
on the type of counterions of the additive alkali metal salts. Details
of the effect of the counterion on the phase transition are in progress
in our laboratory.
a Cr, crystal; G, glass; ND, nematic discotic; Colh, hexagonal columnar;
Iso, isotropic. No indication of enthalpy means that it is too small to be
measured.
Acknowledgment. This work was partly supported by a Grant-
in-Aid for Scientific Research (C) (No. 19550031) from the Japan
Society for the Promotion of Science.
Supporting Information Available: Preparation information,
spectral data of the compounds, and phase transition temperatures and
XRD of the complexes, 1a/LiCl and la/NaOTf (PDF). This material is
Figure 2. Optical textures of ND phases of 1a (a), 1b (b), and 1c (c) on
cooling at 217, 110, and 12 °C, respectively, observed by POM (×600).
The Colh phase of 1a triggered by the addition of 2 molar equiv of LiOTf
on cooling at 200 °C observed by POM (×600) (d).
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