Structure and stability of supramolecular crown ether complexes

Abstract

Despite the fact that the complexation of ammonium cations with ionophores like crown ethers plays an important role in biological and industrial processes, there is still a lack of theoretical methods to reproduce or even predict the host-guest complex structures or their thermodynamic stabilities in an accurate manner. Hence, the development of ionophores has often relied on a trial-and-error approach and the synthetic efforts associated with this have been enormous, so far. Therefore, theoretical methods for the reliable prediction of binding affinities of crown ether derivatives with ammonium ions would be an indispensable tool for the rational design of new receptors with tailored properties. Here, we suggest a computationally efficient but still accurate theoretical approach. It is tested for a model system consisting of 18-crown-6 ether and an ammonium cation, but is invented for application to much larger complexes. The accuracy of various approximate quantum-chemical methods, based on density functional theory (DFT) and many-body perturbation theory, is evaluated against the gold standard CCSD(T) in the basis set limit as internal reference. An important aspect is the consideration of dispersion interactions in DFT methods, for which the dispersion-correction by Grimme was employed. For all selected methods, the basis-set dependence of calculated interaction energies was investigated.

Polyacrylonitrile (PAN)/crown ether composite nanofibers for the selective adsorption of cations

“…Therefore they can selectively bind various ions. 21 This led to the design and synthesis of new crown ethers and various well-dened crown ether polymers. [22][23][24] Owing to their high selectivities, considerable research interest has been devoted to the design of crown ether adsorbents as well.…”

Unlocking single molecule magnetism: a supramolecular strategy for isolating neutral MnIII salen-type dimer in crystalline environments

“…In general, the stabilization energies associated with C–H⋯O interactions are modest, and such interactions are considered unsuitable for promoting supramolecular formation. However, the value is more than one-third of the typical supramolecule of (K + )18C6 (−300.3 kJ mol −1 ) 13 and (NH 4 + )18C6 (−314 kJ mol −1 ), 14 and comparable to the supramolecule of 18C6 and a neutral molecule, benzenesulfonate amide (−104.2 kJ mol −1 ). 15 [Mn(5-MeOsalen)(Cl)] and DB24C8 were assembled as a supramolecule in the crystal.…”

“…Dalton Transactions third of the typical supramolecule of (K + )18C6 (−300.3 kJ mol −1 ) 13 and (NH 4 + )18C6 (−314 kJ mol −1 ), 14 and comparable to the supramolecule of 18C6 and a neutral molecule, benzenesulfonate amide (−104.2 kJ mol −1 ). 15 [Mn(5-MeOsalen)(Cl)] and DB24C8 were assembled as a supramolecule in the crystal.…”

Recognition of silver cations by a cucurbit[8]uril-induced supramolecular crown ether

“…17 As a result, they have attracted significant attention in the development of applications for the solubility enhancement of metal cations in organic solvents, improvement of basicity or general reactivity of metal reagents as bases, nucleophiles or counterions. 18 Furthermore, crown ethers have been employed in a vast variety of fields including biological chemistry, 19,20 molecular machines and phase-transfer catalysis. 21 Accordingly, the supramolecular crown ether designed in our strategy could recognize metal cations in sensor applications (Scheme 1).…”