Transforming a C3-Symmetrical Liquid Crystal to a π-Gelator by Alkoxy Chain Variation

Rational understanding of the structural features involving different noncovalent interactions is necessary to design a liquid crystal (LC) or an organogelator. Herein, we report the effect of the number and positions of alkoxy chains on the self-assembly induced physical properties of a few π-conjugated molecules. For this purpose, we designed and synthesized three C 3 -symmetrical molecules based on oligo( p -phenylenevinylene), C 3 OPV1 - 3 . The self-assembly properties of these molecules are studied in the solid and solution states. All of the three molecules follow the isodesmic self-assembly pathway. Upon cooling from isotropic melt, C 3 OPV1 having nine alkoxy chains (-OC 12 H 25 ) formed a columnar phase with two-dimensional rectangular lattice and retained the LC phase even at room temperature. Interestingly, when one of the -OC 12 H 25 groups from each of the end benzene rings is knocked out, the resultant molecule, C 3 OPV2 lost the LC property, however, transformed as a gelator in toluene and n -decane. Surprisingly, when the -OC 12 H 25 group from the middle position is removed, the resultant molecule C 3 OPV3 failed to form either the LC or the gel phases.