Quantitative formation of a highly strained tricyclic [2.2]paracyclophane derivative from a mixed crystal of ethyl and propyl .alpha.-cyano-4-[2-(4-pyridyl)ethenyl]cinnamates through a topochemical reaction

Yasunari Maekawa; Satoshi Kato; Masaki Hasegawa

doi:10.1021/ja00010a031

ChemInform Abstract: Quantitative Formation of a Highly Strained Tricyclic (2.2) Paracyclophane Derivative from a Mixed Crystal of Ethyl and Propyl . alpha.-Cyano-4-(2-(4-pyridyl)ethenyl)cinnamates Through a Topochemical Reaction.

ChemInform ◽

10.1002/chin.199134150 ◽

2010 ◽

Vol 22 (34) ◽

pp. no-no

Author(s):

Y. MAEKAWA ◽

S. KATO ◽

M. HASEGAWA

Keyword(s):

Mixed Crystal ◽

Topochemical Reaction ◽

Quantitative Formation ◽

Highly Strained

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

10.26434/chemrxiv.7580027.v1 ◽

2019 ◽

Author(s):

Terri Lovell ◽

Curtis Colwell ◽

Lev N. Zakharov ◽

Ramesh Jasti

Keyword(s):

Symmetry Breaking ◽

Theoretical Work ◽

P Systems ◽

Quantum Yields ◽

Size Dependent ◽

New Class ◽

Carbon Carbon Bond ◽

Conjugated Macrocycles ◽

Structural Manipulation ◽

Highly Strained

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

10.26434/chemrxiv.7580027 ◽

2019 ◽

Author(s):

Terri Lovell ◽

Curtis Colwell ◽

Lev N. Zakharov ◽

Ramesh Jasti

Keyword(s):

Symmetry Breaking ◽

Theoretical Work ◽

P Systems ◽

Quantum Yields ◽

Size Dependent ◽

New Class ◽

Carbon Carbon Bond ◽

Conjugated Macrocycles ◽

Structural Manipulation ◽

Highly Strained

[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.

Download Full-text