Synchrotron X-Ray Study of the Orientational OrderingD2−D1Structural Phase Transition of Freely Suspended Discotic Strands in Triphenylene Hexa-n-dodecanoate

We demonstrate the feasibility of x-ray scattering studies of freely suspended strands of discotic liquid crystals (of triphenylene hexa-$n$-dodecanoate). We are able to grow strands, which are stable for days, of diameter > 50 μm with a few single-crystal domains. Unexpectedly, we find that the quasi two-dimensional structural phase transition from columnar $D2$ to columnar $D1$ corresponds to the orientational ordering of columns of molecules with the molecules tilted at finite angles to the column axis in both phases.