Two-walled phthalimide extended calix[4]pyrrole: Experimental and computational anion binding investigations
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Date
2026
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Abstract
In this study, a two-walled phthalimide extended C4P (11) was probed as an anion receptor for tetrabuty
lammonium (TBA) salts of spherical halides, trigonal/tetrahedral oxoanions and linear anions with the aid of
DFT/TD-DFT calculations and UV-vis spectroscopy. Optimized geometries indicate the non-covalent interaction
present between the guest and host. Interestingly, anion receptor complex (11@F
) has been found more reactive
among various studied anion receptor complexes. Furthermore, TD-DFT analyses provided insights into elec
tronic transitions within the studied species and found the absorption spectra in the range of 180 nm to 400 nm.
UV-vis absorbance titrations of receptor 11 with various anions in CH
3
CN have revealed 1:1 binding stoichi
Oxoanions
ometry and considerably higher binding affinities with F‾, Cl‾, CH
3
COO‾, and SCN‾ as compared to the one-
walled phthalimide C4P (13) and simple C4P (1) existing in the literature. Notably, higher anion binding af
f
inities of the receptor 11 as compare to the C4Ps 1 and 13 certifies the contribution of weaker anion
in
teractions from phthalimide subunits as well as the CH–anion interactions from the aliphatic methylene (CH
protons besides primary hydrogen bonding of the pyrrolic NHs-anions as observed from
1
π
H NMR studies.