Predictable Tuning of Absorption Properties in Modular Aromatic Donor-Acceptor Liquid Crystals

This paper demonstrates a combinatorial design strategy in the generation of columnar liquid crystalline materials with tailored properties based on the molar (1:1) combination of complementary electron-rich and electron-poor aromatic components. Through the iterative study of relationships of individual component structure to combined material properties, a series of aromatic donor acceptor columnar liquid crystal materials was developed whose charge-transfer absorption completely spans the visible spectrum. The red-onset of absorption in these materials is shown to correlate closely with straightforward orbital energy level calculations (density functional theory) of individual component molecules. This holds equally true regardless of the component or range of absorption characteristics exhibited by the molecules of this study. Charge-transfer band extinction coefficients are substantial in these materials, ranging from 3800-15500 M-1; the magnitude of which is shown to correlate to component identity. This ability to predictably design a range of functional material properties through preceding calculations, and achieving a tailored diversity of properties through combination of relatively simple component molecules, provides an impressive array of new materials and exemplifies this as a powerful strategy for efficient, targeted material design.