Unusual Formation of Switchable Hexagonal Columnar Phase by Bent-Shaped Molecules with Low Bent-Angle Naphthalene Central Core and Alkylthio Tail

The low-angle bent-shaped molecules with 1,7-naphthalene central core and alkylthio tails can form a novel hexagonal columnar phase and a dark B4 phase. The columnar phase has a large two-dimensional hexagonal lattice with edges of 65--75 $Å$ and exhibits polar switching with spontaneous polarization along the column axis. Calculated from the density (${\sim}1$ g$\cdot$cm -3 ) and unit volume, the number of molecules that are necessary to fill a 4.6-$Å$ stratum of each column were found to be ${\sim}11$. Such a large number of molecules can be accommodated only in the tube-like assembly, which may be the first example as formed by the usual bent-shaped molecule with a single alkylthio tail.