Useful synthetic artifacts? The impact of ubiquitous linker-adjacent groups on the self-assembly of discotic dimers.

Abstract

Although discotic dimers commonly feature bulky ether substituents adjacent to the linking group, the impact of these chains on self-assembly remains unclear. A series of dibenzo[a,c]phenazine dimers with alkoxy groups ortho to the linker were prepared and their solution conformational dynamics and liquid crystalline properties examined. The presence of a methoxy substitutent adjacent to the bridging group increased the phase stability, whereas longer chains dramatically decreased clearing temperatures. NMR solution studies indicated that adjacent groups increased the preference of dimers to adopt unfolded conformers. DFT models indicated that the unfolded structures were nonplanar and hence less compatible with columnar ordering, leading to a destabilization of the mesophases.