High One-Dimensional Charge Mobility in Semiconducting Columnar Mesophases of Isocyano-Triphenylene Metal Complexes

This paper reports the synthesis, liquid crystal behavior, and charge-transport properties in the mesophase of isocyano-triphenylene gold, copper, palladium, and platinum complexes [MX(CNR)] (CNR = 2-(6-(4-isocyanophenoxy)hexyloxy)-3,6,7,10,11-pentakisdodecyloxytriphenylene; M = Au, X = Cl, C6F5, C6F4OC10H21, CN; M = Cu, X = Cl), [(μ-4,4⠲-C6F4C6F4)Au(CNR)2], [(μ-Cl2)Cu(CNR)22], and [MX2(CNR)2] (M = Pd, Pt; X = Cl, Br, I, and M = Pt, X = CN). The thermal and electronic properties of these materials are modulated by the metal fragment. The complexes that display columnar mesomorphism are those that support more than one triphenylene per molecule or those that produce a similar effect by dipole-dipole interactions between the metal groups. These circumstances improve the balance of favorable enthalpic interactions versus unfavorable entropic contributions into a columnar stacking. Hybrid inorganic/organic dual columnar mesophases with high SCLC hole mobility along the columnar stacking, above 1 cm2V-1s-1, have been found. It is worth noting that the dicyanoplatinum complex displays mesophase phosphorescence based on Pt···Pt interactions.