Using Ïnternal Free Volume” to Increase Chromophore Alignment.

Triptycenes have general applicability for increasing the alignment of fluorescent and dichroic dyes in LC hosts. Dyes contg. varying nos. of triptycenes were synthesized to study the effect of free-vol. alignment of triptycenes on the alignment of dyes. These dyes were designed such that multiple triptycenes could be incorporated and the triptycene-free vol. is coincident to the aspect ratio of the dye, allowing a cooperative effect to increase their overall av. alignment. With increasing triptycene incorporation, a stepwise increase in the alignment parameters of each dye was seen. It was also found that the attachment of one triptycene group has a negligible effect on the optical switching response times of the dyes. This can be a powerful tool for designing dyes with higher alignments for a variety of applications including guest-host reflective LCDs and holog. data storage. [on SciFinder(R)]