A Hexahomotrioxacalix[3]arene-Based Ditopic Receptor for Alkylammonium Ions Controlled by Ag+ Ions

Abstract

A receptor cone-1 based on a hexahomotrioxacalix[3]arene bearing three pyridyl groups was successfully synthesized, which has a C3-symmetric conformation and is capable of binding alkylammonium and metal ions simultaneously in a cooperative fashion. It can bind alkylammonium ions through the π-cavity formed by three aryl rings. This behaviour is consistent with the cone-in/cone-out conformational rearrangement needed to reorganize the cavity for endo-complexation. As a C3-symmetrical pyridyl-substituted calixarene, receptor cone-1 can also bind an Ag+ ion, and the nitrogen atoms are turned towards the inside of the cavity and interact with Ag+. After complexation of tris(2-pyridylamide) derivative receptor cone-1 with Ag+, the original C3-symmetry was retained and higher complexation selectivity for n-BuNH3+ versus t-BuNH3+ was observed. Thus, it is believed that this receptor will have a role to play in the sensing, detection, and recognition of Ag+ and n-BuNH3+ ions.

Calix[3]arene-Analogous Metacyclophanes: Synthesis, Structures and Properties with Infinite Potential

“…The geometries of the molecular structures were optimized in the gas phase using the PBE0 functional theory with the LANL2DZ basis set. The calculated binding or interaction energies (IE) for cone- 35 ⊃ n -BuNH 3 + , cone- 35 ⊃ t -BuNH 3 + , cone- 35 ⊃Ag + , and n BuNH 3 + ⊂ [ cone - 35 ⊃Ag + ] are −298.8 kJ mol −1 , −268.3 kJ mol −1 , −457.1 kJ mol −1 , and –525.8 kJ·mol −1 , respectively, and were in agreement with the trend for the complexation data determined by the 1 H-NMR spectroscopic titration experiments with the corresponding perchlorate salts [ 57 ]. A conceptualization of the complexation of n BuNH 3 + by the receptor cone- 35 is shown in Figure 15 .…”

“…⊃n-BuNH3 + , cone-35 ⊃t-BuNH3 + , cone-35 ⊃Ag + , and nBuNH3 + ⊂ [cone-35 ⊃Ag + ] are −298.8 kJ mol −1 , −268.3 kJ mol −1 , −457.1 kJ mol −1 , and -525.8 kJ•mol −1, respectively, and were in agreement with the trend for the complexation data determined by the 1 H-NMR spectroscopic titration experiments with the corresponding perchlorate salts[57]. A conceptualization of the complexation of nBuNH3 + by the receptor cone-35 is shown in Figure15.…”

“…Recently, 35 the C 3 -symmetric N -pyridyl O -methylacetamido functionalized derivative of 31 ( Figure 14 ) was reported to be able to selectively and cooperatively bind Ag + and n -butylammonium ions and be controlled by the metal ion [ 57 ]. The geometries of the molecular structures were optimized in the gas phase using the PBE0 functional theory with the LANL2DZ basis set.…”

“…The green circles represent the CONH− and the hexagons represent the pyridyl groups. (Figure take from [ 57 ]).…”

“…Left: The free cone - 35 , Middle: 1:1 cone - 35 ⊃Ag + complex, and right: n BuNH 3 + ⊂ [ cone -35 ⊃Ag + ] complex. Figure taken from reference [ 57 ].…”