Indolocarbazole as a Platform for Concatenated Crystalline Rotors

• Published in: Crystal growth & design Vol. 23; no. 9; pp. 6785 - 6794
• Main Authors: Hernández-Morales, Ernesto A., Colin-Molina, Abraham, Arcudia, Jessica, Hernández, Federico J., Rodríguez, Mario, Toscano, Ruben A., Crespo-Otero, Rachel, Merino, Gabriel, Rodríguez-Molina, Braulio
• Format: Journal Article
• Language: English
• Published: American Chemical Society 06.09.2023
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.3c00650

Herein, we describe a series of molecular rotors formed by cocrystallizing three indolo­[3,2-b]­carbazole (ICZ) derivatives with butyl and cyclohexyl substituents, along with 1,4-diaza[2.2.2]­bicyclooctane (DABCO). The structures of rotors I and III were confirmed through single-crystal X-ray diffraction (SCXRD), revealing a concatenated 1D arrangement between the two components. Variable-temperature (VT) SCXRD experiments on rotors I and III suggested that the rotator shows rotational motion, with activation energies of 6.8 and 1.8 kcal mol–1, respectively. The lower activation energy for rotor III was attributed to the flexible environment around DABCO due to the presence of cyclohexyl groups, while the surroundings of rotor I were found to be more rigid. Additionally, our predictions of radiative and nonradiative decay constants indicate that the vibrations of the molecular rotors impact nonradiative decay rates and, consequently, the fluorescence quantum yields.