New Class of Hydroxy-Substituted Squaraine Rotaxane.

Australian Journal of Chemistry
Na FuBradley D Smith

Abstract

A templated macrocyclization reaction was used to permanently encapsulate a highly fluorescent hydroxy-substituted squaraine dye inside a tetralactam macrocycle. The free squaraine dye is quite rigid due to internal hydrogen bonding and its photophysical properties hardly change upon encapsulation. A combination of X-ray and NMR data show that the surrounding tetralactam macrocycle adopts an unusually rigid chair conformation and does not undergo rapid pirouetting. Because of its large size and conformational rigidity, the macrocycle creates anisotropic NMR shielding zones that extend over the N,N-dibutylamino groups at each end of the squaraine thread. This shielding anisotropy allows hindered aryl-N rotation to be observed by NMR and provides direct experimental evidence that quinoid-like resonance structures are major contributors to the bis(N,N-dialkylaminophenyl)squaraine resonance hybrid.

References

Mar 10, 2005·Journal of the American Chemical Society·Easwaran ArunkumarBradley D Smith
Jun 28, 2008·Organic Letters·Jeremiah J GassensmithBradley D Smith
Feb 12, 2009·Physical Chemistry Chemical Physics : PCCP·Denis JacqueminCarlo Adamo
Jul 31, 2009·The Journal of Organic Chemistry·Na FuBradley D Smith
Oct 21, 2009·Chemical Communications : Chem Comm·Jeremiah J GassensmithBradley D Smith

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Citations

Apr 21, 2017·Journal of the American Chemical Society·Wenqi LiuBradley D Smith
Jul 20, 2018·Chemistry : a European Journal·Scott K ShawBradley D Smith
Oct 4, 2019·European Journal of Organic Chemistry·Hannah H McGarraughBradley D Smith
May 20, 2011·Chemical Communications : Chem Comm·Jung-Jae LeeBradley D Smith
Dec 21, 2010·The Journal of Organic Chemistry·Ivan MurguBradley D Smith
May 21, 2013·Organic Letters·Evan M PeckBradley D Smith
Mar 16, 2018·Organic Letters·Qi-Wei ZhangBradley D Smith

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Methods Mentioned

BETA
X-ray
NMR
column chromatography

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