Control of the Organization of 4,4′-bis(carbazole)-1,1′-biphenyl (CBP) Molecular Materials through Siloxane Functionalization

We show that through the introduction of short dimethylsiloxane chains, it was possible to suppress the crystalline state of CBP in favor of various types of organization, transitioning from a soft crystal to a fluid liquid crystal mesophase, then to a liquid state. Characterized by X-ray scattering, all organizations reveal a similar layered configuration in which layers of edge-on lying CBP cores alternate with siloxane. The difference between all CBP organizations essentially lay on the regularity of the molecular packing that modulates the interactions of neighboring conjugated cores. As a result, the materials show quite different thin film absorption and emission properties, which could be correlated to the features of the chemical architectures and the molecular organizations.

Automated summary

By introducing short dimethylsiloxane chains, the crystalline state of CBP can be suppressed, leading to different types of organization, including a soft crystal, a fluid liquid crystal mesophase, and a liquid state. X-ray scattering analysis shows that all organizations exhibit a layered configuration with alternating CBP cores and siloxane. The different organizations of CBP primarily differ in their molecular packing regularity, which modifies the interactions between neighboring conjugated cores. Consequently, the thin film absorption and emission properties of the materials vary, correlating with their chemical architectures and molecular organizations.