Chasing Self-Assembly of Thioether-Substituted Flavylium Salts in Solution and Bulk State

Two series of flavylium triflates carrying alkoxy side chains in the A‐ring (benzo unit of chromylium salt) and thioethers in the B ring (phenyl unit) (O_n‐Fla‐S_m) as well as thioethers at both A and B ring (S_n‐Fla‐S_m) were synthesized in order to understand the effect of thioether functionalization on their self‐assembly and electronic properties. Concentration‐dependent and diffusion ordered (DOSY) NMR experiments of O₁‐iV‐Fla‐S₃ indicate the formation of columnar H‐aggregates in solution with antiparallel intracolumnar stacking of the AC unit (chromylium) of the flavylium triflate, in agreement with the solid state structure of O₁‐V‐Fla‐S₁. Thioether substitution on the B ring changes the linear optical properties in solution, whereas it has no effect on the A ring. According to differential scanning calorimetry, polarizing optical microscopy and X‐ray diffraction bulk self‐assembly of these ionic liquid crystals (ILCs) depends on the total number of side chains, yielding SmA and Lam_Col phases for ILCs with 2–3 chains and Col_ro, Col_h phases for ILCs with 3–6 chains. Thus, we demonstrated that thioethers are a useful design tool for ILCs with tailored properties.

Luminescent imidazolium–naphthalene salts in liquid and solid states

This article describes highly luminescent ionic compounds in liquid and crystalline states, where a naphthalene moiety is conjugated to an imidazolium center decorated with two different lengths of alkyl chains.