Synthesis, Structure, and
Fullerene-Complexing Property
of Azacalix[6]aromatics
Shi-Xin Fa
Li-Xia Wang
De-Xian Wang
Liang Zhao
Mei-Xiang Wang
10.1021/jo5003714.s010
https://acs.figshare.com/articles/dataset/Synthesis_Structure_and_Fullerene_Complexing_Property_of_Azacalix_6_aromatics/2304781
Synthesis, structure, and fullerene-binding
property of azacalix[6]aromatics
were systematically studied. By means of [3 + 3] and [2 + 2 + 2] fragment
coupling protocols, a number of azacalix[6]aromatics containing
different combinations of benzene, pyridine, and pyrimidine rings
and various substituents on the bridging nitrogen atoms were synthesized
conveniently in moderate to good yields. The resulting macrocycles
adopt in the solid state symmetric and heavily distorted 1,3,5-alternate
conformations depending on the aromatic building units, whereas, in
solution, they exist as a mixture of conformers that undergo rapid
interchanges relative to the NMR time scale. All macrocycles were
able to form 1:1 complexes with C<sub>60</sub> and C<sub>70</sub> in
toluene with the association constants up to 7.28 × 10<sup>4</sup> M<sup>–1</sup>. In the crystalline state, azacalix[6]aromatics
form complexes with C<sub>60</sub> and C<sub>70</sub> with 2:1, 1:1,
and 1:2 stoichiometric ratios between host and guest. Azacalix[6]aromatics
interact with fullerene by forming mainly the sandwich structure in
which C<sub>60</sub> or C<sub>70</sub> is sandwiched by two macrocycles.
X-ray molecular structures revealed that multiple π–π
and CH−π interactions between concave azacalix[6]aromatics
and convex fullerenes C<sub>60</sub> and C<sub>70</sub> contribute
a joint driving force to the formation of host–guest complexes.
2014-04-18 00:00:00
Azacalix
fullerenes C 60
host
macrocycle
azacalix
CH
C 70
NMR time scale
complex
C 60