Molecular Assemblies of Tetrahedral Triphenylmethanol and Triphenylamine Derivatives Bearing −NHCOC_<i>n</i>H_2<i>n</i>+1 Chains

Abstract

Nonplanar three-fold symmetrical triphenylmethanol (1: n = 10 and 2: n = 3) and triphenylamine (3: n = 10 and 4: n = 3) derivatives bearing three alkylamide (−NHCO­CnH2n+1) chains were studied in terms of their phase transitions, molecular assemblies, nano- or meso-structures, and dielectric responses. Slight modification of the structural core from a hydroxyl moiety (C–OH in 1) to a nitrogen atom (N in 3) drastically changed the molecular assembly structures and physical properties in solids. The molecular assembly of 1 showed a glass–plastic crystal phase transition at ∼340 K, whereas 3 only displayed a direct solid–liquid phase transition. Uniform microscale spheres and nanowires with average diameters of 2 μm and 200 nm, respectively, were observed for the molecular assemblies of 1 and 3 on substrate surfaces, respectively, corresponding to amorphous glass and one-dimensional hydrogen-bonding columnar structures. An α-type frequency- and temperature-dependent dielectric relaxation was observed in amorphous 1 during the glass–plastic crystal phase transition, whereas no dielectric anomalies were observed for 3. This difference was attributed to the subtle chemical modification of the central core from C–OH to N