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Jasti_Symmetry Breaking and the Turn-On Fluorescence of Small, Highly Strained Carbon Nanohoops.pdf (5.22 MB)

Symmetry Breaking and the Turn-On Fluorescence of Small, Highly Strained Carbon Nanohoops

submitted on 12.01.2019, 00:23 and posted on 14.01.2019, 16:52 by Terri Lovell, Curtis Colwell, Lev N. Zakharov, Ramesh Jasti

[n]Cycloparaphenylenes, or “carbon nanohoops,” are unique conjugated macrocycles with radially oriented p-systems similar to those in carbon nanotubes. The centrosymmetric nature and conformational rigidity of these molecules lead to unusual size-dependent photophysical characteristics. To investigate these effects further and expand the family of possible structures, a new class of related carbon nanohoops with broken symmetry is disclosed. In these structures, referred to as meta[n]cycloparaphenylenes, a single carbon-carbon bond is shifted by one position in order to break the centrosymmetric nature of the parent [n]cycloparaphenylenes. Advantageously, the symmetry breaking leads to bright emission in the smaller nanohoops, which are typically non-fluorescent due to optical selection rules. Moreover, this simple structural manipulation retains one of the most unique features of the nanohoop structures-size dependent emissive properties with relatively large extinction coefficents and quantum yields. Inspired by earlier theoretical work by Tretiak and co-workers, this joint synthetic, photophysical, and theoretical study provides further design principles to manipulate the optical properties of this growing class of molecules with radially oriented p-systems.


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University of Oregon



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