Mesogenic [Rh(L)4](A) complexes form mesophases with RhI⋯RhI-containing and triphenylene-discotic segregated columns. Effect of RhI⋯RhI interactions and A− = [Au(CN)2]− on hole mobility

Abstract

RhI complexes [Rh(L)4](A) (A− = Cl−, BF4−, [Au(CN)2]−) with conventional arylisocyanides (p-MeC6H4(NC), LA; p-MeOC6H4(NC), LB; 3,5-(OMe)2C6H3(NC), LC) or with the alkoxy-functionalized triphenylene-arylisocyanides TPh(OC12H25)5(O(CH2)6OC6H4(NC)-p) (LD1) and TPh(OC12H25)5(O(CH2)6OC6H2Me2(NC)-p) (LD2), have been prepared and their self-assembly, aggregation, optical, redox, mesogenic and conducting properties investigated. Intermolecular π–π stacking, RhI⋯RhI, and RhI⋯AuI interactions rule the crystal packing and aggregation in solution for the complexes with LA, LB, and LC. For the RhI complexes with the alkoxy-functionalized-triphenylene isocyanides LD1 and LD2 mesogenic behaviour is induced, giving rise to multicolumnar mesophases in broad temperature ranges (ca. 70–160 °C). Detailed analysis (POM, DSC, SAXS/WAXS and GIWAXS) of the columnar mesophases has allowed us to propose precise packing models that explain the diverse supramolecular arrangements found in the nanostructured condensed phases. Columnar alignments predominantly with Rh⋯Rh interactions (or Rh⋯Au, only for LD2 in specific conditions) are observed, depending on the aligning conditions. The hole mobility in the columnar mesophases of the complexes with Rh⋯Rh interactions are ∼1 cm2 V−1 s−1, that is up to four orders of magnitude higher than those reported for columnar mesophases of organic triphenylene derivatives, and increases one order of magnitude further in the mesophases containing the [Au(CN)2]− counteranion.