Hydrogen bonding induced supramolecular self-assembly of linear doubly discotic triad supermolecules

A series of linear doubly discotic triad supermolecules based on a porphyrin (P) core and two triphenylene (Tp) arms linked by amide bonds are synthesized. The samples are denoted as P(Tp)(2). Hydrogen bonding along the P stacks is the primary driving force for the supramolecular self-assembly of P(Tp)(2) triad supermolecules. Meanwhile, the degree of coupling between P and Tp disks also plays an important role. For samples with the spacer lengths longer than or similar to the alkyl chain lengths in the Tp arms, P and Tp are decoupled to a large degree. This decoupling result in non-uniform tilt angles for P and Tp disks along both the a- and c-axes. Therefore, large unit cells are observed with eight P(Tp)(2) supermolecules per cell. For a sample with the spacer length much shorter than the alkyl chains in the Tp arms, P and Tp are strongly coupled. Therefore, both P and Tp have uniform tilt angles along the a- and c-axes. A small unit cell is obtained with only one P(Tp)(2) supermolecule per cell.