Tuning the energy level of TAPC: crystal structure and photophysical and electrochemical properties of 4,4′-(cyclohexane-1,1-diyl)bis[N,N-bis(4-methoxyphenyl)aniline]

The energy level of a hole-transporting material (HTM) in organic electronics, such as organic light-emitting diodes (OLEDs) and perovskite solar cells (PSCs), is important for device efficiency. In this regard, we prepared 4,4′-(cyclo­hexane-1,1-di­yl)bis­[N,N-bis­(4-meth­oxy­phen­yl)aniline] (TAPC-OMe), C46H46N2O4, to tune the energy level of 4,4′-(cyclo­hexane-1,1-di­yl)bis­[N,N-bis­(4-methylphenyl)aniline] (TAPC), which is a well-known HTM commonly used in OLED applications. A systematic characterization of TAPC-OMe, including 1H and 13C NMR, elemental analysis, UV–Vis absorption, fluorescence emission, density functional theory (DFT) calculations and single-crystal X-ray diffraction, was performed. TAPC-OMe crystallized in the triclinic space group P\overline{1}, with two mol­ecules in the asymmetric unit. The dihedral angles between the central amine triangular planes and those of the phenyl groups varied from 26.56 (9) to 60.34 (8)° due to the steric hindrance of the central cyclo­hexyl ring. This arrangement might be induced by weak hydrogen bonds and C—H⋯π(Ph) inter­actions in the extended structure. The emission maxima of TAPC-OMe showed a significant bathochomic shift compared to that of TAPC. A strong dependency of the oxidation potentials on the nature of the electron-donating ability of substituents was confirmed by comparing oxidation potentials with known Hammett parameters (σ).