Structure and stability of supramolecular crown ether complexes.

Area of Science:

• Computational chemistry
• Supramolecular chemistry

Background:

• Accurate theoretical prediction of host-guest complex structures and thermodynamic stabilities for ionophores like crown ethers and ammonium ions is lacking.
• Current ionophore development often relies on inefficient trial-and-error methods, demanding significant synthetic effort.

Purpose of the Study:

• To develop a computationally efficient and accurate theoretical approach for predicting binding affinities between crown ether derivatives and ammonium ions.
• To provide a tool for the rational design of novel ionophores with specific properties.

Main Methods:

• Evaluation of approximate quantum-chemical methods, including density functional theory (DFT) and many-body perturbation theory.
• Comparison of method accuracy against the CCSD(T) gold standard in the basis set limit.
• Inclusion of dispersion interactions using Grimme's dispersion correction in DFT methods.
• Investigation of basis-set dependence for calculated interaction energies.

Main Results:

• The study tested a computationally efficient theoretical approach on a model system of 18-crown-6 ether and an ammonium cation.
• Accuracy of various DFT and many-body perturbation theory methods was assessed against CCSD(T).
• The influence of dispersion interactions and basis set size on binding energy calculations was analyzed.

Conclusions:

• The proposed theoretical approach offers a computationally feasible yet accurate method for studying ionophore-guest interactions.
• This method can significantly aid in the rational design and development of advanced ionophores for ammonium ion complexation.
• Further application to larger and more complex systems is anticipated.