Fingerprint of Aromaticity and Molecular Topology on the Photophysical Properties of Octaphyrins
| Autor: | Tatiana Woller, Benoît Champagne, Mercedes Alonso, Paul Geerlings, Frank De Proft |
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| Přispěvatelé: | Faculty of Sciences and Bioengineering Sciences, Chemistry, Vriendenkring VUB, Quantum Chemistry - Molecular Modelling, General Chemistry |
| Rok vydání: | 2019 |
| Předmět: |
Physics
Ideal (set theory) Fingerprint (computing) food and beverages Aromaticity 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials General Energy Physical and Theoretical Chemistry Molecular topology 0210 nano-technology Biological system |
| Zdroj: | The Journal of Physical Chemistry C. 123:7318-7335 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/acs.jpcc.8b10908 |
| Popis: | Expanded porphyrins are currently recognized as the ideal test bed to explore the correlation between molecular properties and (anti)aromaticity since they can adopt different π-conjugation topologies and change easily the number of π-electrons along the conjugation pathway. From recent studies, aromaticity indeed emerges as the guiding concept to rationalize the spectroscopic features and the two-photon absorption cross sections in expanded porphyrins. However, from the theoretical point of view, the complex structure-property relationship between aromaticity, π-conjugation topology, and photophysical properties is not fully understood yet. To unravel such structure-property relationships, we focused on octaphyrin(1.1.1.1.1.1.1.1) macrocycles since they are flexible enough to provide twisted-Hückel, Möbius, and Hückel untwisted topologies with distinct aromaticity character. In this work, the (anti)aromaticity of the different states was first quantified using different aromaticity criteria. Second, the fingerprints of aromaticity on UV/vis spectra were elucidated. Importantly, we found that the absorption spectra of certain antiaromatic Hückel structures are characterized by more intense absorption bands than its aromatic homologues, contrary to the general statement that antiaromatic expanded porphyrins exhibit significantly attenuated absorption bands compared to aromatic ones. Finally, the role of aromaticity and π-conjugation topology on linear and nonlinear optical properties was scrutinized and our results pinpoint the importance of molecular topology and symmetry on the first and second hyperpolarizabilities. Overall, we demonstrate that expanded porphyrins upon topology interconversions can act as efficient nonlinear optical switches. © |
| Databáze: | OpenAIRE |
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