2 research outputs found
Polyamide–Polyamine Cryptand as Dicarboxylate Receptor: Dianion Binding Studies in the Solid State, in Solution, and in the Gas Phase
Polyamide–polyamine
hybrid macrobicycle <b>L</b> is
explored with respect to its ability to bind α,ω-dicarboxylate
anions. Potentiometric studies of protonated <b>L</b> with the
series of dianions from succinate (suc<sup>2–</sup>) through
glutarate (glu<sup>2–</sup>), α-ketoglutarate (kglu<sup>2–</sup>), adipate (adi<sup>2–</sup>), pimelate (pim<sup>2–</sup>), suberate (sub<sup>2–</sup>), to azelate
(aze<sup>2–</sup>) have shown adipate preference with association
constant value of <i>K</i> = 4900 M<sup>–1</sup> in
a H<sub>2</sub>O/DMSO (50:50 <i>v/v</i>) binary solvent
mixture. The binding constant increases from glu<sup>2–</sup> to adi<sup>2–</sup> and then continuously decreases with
the length of the anion chain. Further, potentiometric studies suggest
that hydrogen bonding between the guest anions and the amide/ammonium
protons of the receptor also contributes to the stability of the associations
along with electrostatic interactions. Negative-mode electrospray
ionization of aqueous solutions of host–guest complexes shows
clear evidence for the selective formation of 1:1 complexes. Single-crystal
X-ray structures of complexes of the receptor with glutaric acid,
α-ketoglutaric acid, adipic acid, pimelic acid, suberic acid,
and azelaic acid assist to understand the observed binding preferences.
The solid-state structures reveal a size/shape complementarity between
the host and the dicarboxylate anions, which is nicely reflected in
the solution state binding studies
Polyamide–Polyamine Cryptand as Dicarboxylate Receptor: Dianion Binding Studies in the Solid State, in Solution, and in the Gas Phase
Polyamide–polyamine
hybrid macrobicycle <b>L</b> is
explored with respect to its ability to bind α,ω-dicarboxylate
anions. Potentiometric studies of protonated <b>L</b> with the
series of dianions from succinate (suc<sup>2–</sup>) through
glutarate (glu<sup>2–</sup>), α-ketoglutarate (kglu<sup>2–</sup>), adipate (adi<sup>2–</sup>), pimelate (pim<sup>2–</sup>), suberate (sub<sup>2–</sup>), to azelate
(aze<sup>2–</sup>) have shown adipate preference with association
constant value of <i>K</i> = 4900 M<sup>–1</sup> in
a H<sub>2</sub>O/DMSO (50:50 <i>v/v</i>) binary solvent
mixture. The binding constant increases from glu<sup>2–</sup> to adi<sup>2–</sup> and then continuously decreases with
the length of the anion chain. Further, potentiometric studies suggest
that hydrogen bonding between the guest anions and the amide/ammonium
protons of the receptor also contributes to the stability of the associations
along with electrostatic interactions. Negative-mode electrospray
ionization of aqueous solutions of host–guest complexes shows
clear evidence for the selective formation of 1:1 complexes. Single-crystal
X-ray structures of complexes of the receptor with glutaric acid,
α-ketoglutaric acid, adipic acid, pimelic acid, suberic acid,
and azelaic acid assist to understand the observed binding preferences.
The solid-state structures reveal a size/shape complementarity between
the host and the dicarboxylate anions, which is nicely reflected in
the solution state binding studies