Hydrogen-Bonded Complexes of Aromatic Crown Ethers with
(9-Anthracenyl)methylammonium Derivatives. Supramolecular
Photochemistry and Photophysics. pH-Controllable
Supramolecular Switching<sup>†</sup>
Peter R. Ashton
Roberto Ballardini
Vincenzo Balzani
Marcos Gómez-López
Simon E. Lawrence
M. Victoria Martínez-Díaz
Marco Montalti
Arianna Piersanti
Luca Prodi
J. Fraser Stoddart
David J. Williams
10.1021/ja9715760.s001
https://acs.figshare.com/articles/journal_contribution/Hydrogen-Bonded_Complexes_of_Aromatic_Crown_Ethers_with_9-Anthracenyl_methylammonium_Derivatives_Supramolecular_Photochemistry_and_Photophysics_pH-Controllable_Supramolecular_Switching_sup_sup_/3666126
The (9-anthracenyl)methylammonium and
(9-anthracenyl)benzylammonium
tetrakis(hexafluorophosphate)
salts give hydrogen-bonded complexes in
CH<sub>2</sub>Cl<sub>2</sub> with aromatic crown ethers
containing dibenzo (<b>DB</b>) or dinaphtho
(<b>DN</b>) units. The association constants vary from 3 ×
10<sup>3</sup> to 1 × 10<sup>6</sup> M<sup>-1</sup>
in CH<sub>2</sub>Cl<sub>2</sub>, depending on the
specific
ammonium cation and crown ether involved. In a number of cases,
pseudorotaxane-like geometries for the complexes
are demonstrated by (a) <sup>1</sup>H NMR spectroscopy in solution,
(b) X-ray crystallography in the solid state, and (c) mass
spectrometry in the gas phase. The results obtained by absorption,
emission, and excitation spectroscopy and excited
lifetimes show that, as a consequence of the hydrogen bond driven
recognition process, the anthracene chromophoric
unit interacts with the aromatic units of the crown ethers. In the
complexes involving the <b>DB18C6</b>, <b>DB24C8</b>,
and
<b>DB30C10</b> macrocycles, the interaction leads to the complete
quenching of the fluorescence of the dialkoxybenzene
moieties and parallels sensitization of the anthracene fluorescence.
In the complexes of <b>1/5-DN38C10</b>, both the
crown and the anthracene fluorescence are completely quenched, most
likely by an energy-transfer cascade involving
the triplet state of the dialkoxynaphthalene moiety. In the
complexes of <b>2/3-DN30C10</b>, the interaction between
the
anthracene moiety and the naphthalene rings of the crown ether is
relatively strong, as indicated by the perturbation
of the absorption bands, the disappearance of the fluorescence bands of
the naphthalene- and anthracene-type
chromophoric units, and the appearance of a new, broad fluorescence
band. The complexes can also be formed by
addition of CF<sub>3</sub>COOH or
CF<sub>3</sub>SO<sub>3</sub>H to
CH<sub>2</sub>Cl<sub>2</sub> solutions containing crown ether
and amine. The association process
between <b>DB24C8</b> and (9-anthracenyl)benzylammonium salt
can be reversed quantitatively upon addition of a suitable
base and the complex can be formed again after treatment with
acid.
1997-11-05 00:00:00
DB 30C macrocycles
crown ethers
anthracenyl
1 H NMR spectroscopy
anthracene chromophoric unit
38C
anthracene fluorescence
CH 2 Cl 2
18C
CF 3 COOH
DN
crown ether
complex
DB 24C
Aromatic Crown Ethers
CH 2 Cl 2 solutions