Nanoscale Organization and Solid-State Dynamics of Carbazole-[pi]-Carbazole Rotors Edged with Aliphatic Chains
Por:
Aguilar-Granda A., García-González M.C., Pérez-Estrada S., Kozina A., Rodríguez-Molina B.
Publicada:
29 nov 2018
Ahead of Print:
1 ene 2018
Resumen:
The aggregation behavior and its influence on the intramolecular motion
of three highly conjugated solid-state molecular rotors 2-4 with alkyl
groups were investigated by a combination of fluorescence spectroscopy,
transmission electron microscopy (TEM), powder X-ray diffraction (PXRD),
and variable-temperature solid-state H-2 nuclear magnetic resonance (VT
H-2 ssNMR). Their long conjugation made them highly emissive in
tetrahydrofuran solution (Phi(f) = 0.41, 0.21, and 0.18, for rotors 2, 3
and 4, respectively), and the elongated aromatic cores favored pi-pi
intermolecular interactions upon aggregation in hexane. The TEM
micrographs and PXRD studies of the resulting bulk showed that shorter
chains generated larger amorphous domains in 2, as compared to 3 and 4.
The H-2 ssNMR experiments showed fast intramolecular rotation of their
central 1,4-diethynylphenylenes with the lowest activation energy to
rotation for compound 2, E-a = 5.34 kcal/mol. This relationship between
amorphous/crystalline domains and intramolecular motion has not been
reported before, and it could guide the design of new solid-state
molecular rotors.
Filiaciones:
Aguilar-Granda A.:
Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México, 04510, Mexico
García-González M.C.:
Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México, 04510, Mexico
Pérez-Estrada S.:
Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095, United States
Área Académica de Química, Centro de Investigaciones Químicas, Universidad Autónoma Del Estado de Hidalgo, Km 4.5 Carretera Pachuca-Tulancingo, Ciudad Del Conocimiento, Mineral de la Reforma, Hidalgo, 42184, Mexico
Kozina A.:
Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México, 04510, Mexico
Rodríguez-Molina B.:
Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México, 04510, Mexico
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