Tetrahedraphene: A Csp3-centered 3D Molecular Nanographene Showing Aggregation-Induced Emission |
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Authors: | Arturo Oró Fernando Romeo-Gella Dr Josefina Perles Dr Jesús M Fernández-García Prof?Dr Inés Corral Prof?Dr Nazario Martín |
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Institution: | 1. Departamento de Química Orgánica, Facultad de Química, Universidad Complutense de Madrid, Avd. Complutense S/N, 28040 Madrid, Spain;2. Departamento de Química, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain;3. Laboratorio de Difracción de Rayos X de Monocristal, SIdI, Universidad Autónoma de Madrid, C/Francisco Tomás y Valiente, 7. Campus de Cantoblanco, 28049 Madrid, Spain |
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Abstract: | The bottom-up synthesis of 3D tetrakis(hexa-peri-hexabenzocoronenyl)methane, “tetrahedraphene”, is reported. This molecular nanographene constituted by four hexa-peri-hexabenzocoronene (HBC) units attached to a central sp3 carbon atom, shows a highly symmetric arrangement of the HBC units disposed in the apex of a tetrahedron. The X-ray crystal structure reveals a tetrahedral symmetry of the molecule and the packing in the crystal is achieved mostly by CH???π interactions since the interstitial solvent molecules prevent the π???π interactions. In solution, tetrahedraphene shows the same electrochemical and photophysical properties as the hexa-tBu-substituted HBC (tBu-HBC) molecule. However, upon water addition, it undergoes a fluorescence change in solution and in the precipitated solid, showing an aggregation induced emission (AIE) process, probably derived from the restriction in the rotation and/or vibration of the HBCs. Time-Dependent Density Functional Theory (TDDFT) calculations reveal that upon aggregation, the high energy region of the emission band decreases in intensity, whereas the intensity of the red edge emission signal increases and presents a smoother decay, compared to the non-aggregated molecule. All in all, the excellent correlation between our simulations and the experimental findings allows explaining the colour change observed in the different solutions upon increasing the water fraction. |
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Keywords: | 3D Nanographene Aggregation-Induced Emission Bottom-up Synthesis Molecular Nanographene X-Ray Diffraction |
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