Attracting Opposites: Promiscuous Ion-π Binding in the Nucleobases

Area of Science:

• * Physical Chemistry
• * Biochemistry
• * Molecular Biology

Background:

• * Ion-π interactions are strong noncovalent forces crucial in biological and chemical systems.
• * Understanding selectivity and flexibility in ion-π binding is key to molecular recognition.
• * DNA/RNA nucleobases are fundamental biological molecules with π-systems.

Purpose of the Study:

• * To investigate the promiscuous ion-π binding capabilities of DNA/RNA nucleobases.
• * To analyze the driving forces behind cation-π and anion-π complex formation.
• * To elucidate the role of electrostatics and charge penetration in these interactions.

Main Methods:

• * Quantum-mechanical calculations at the CCSD(T)/CBS level for binding energies.
• * Symmetry-Adapted Perturbation Theory (SAPT) for energy decomposition analysis.
• * Theoretical case study focused on DNA/RNA nucleobases with Li+/Na+ and F-/Cl-.

Main Results:

• * DNA/RNA nucleobases exhibit promiscuous binding with both cations (Li+, Na+) and anions (F-, Cl-).
• * Ring-independent potentials stabilize both cation- and anion-π complexes, counteracted by electrostatics.
• * Charge penetration effects significantly influence the electrostatics of anion-π systems.

Conclusions:

• * Promiscuous ion-π binding is an inherent property of π-systems, not limited to nucleobases.
• * A unified view of cation- and anion-π interactions emerges, explaining binding energy correlations.
• * Findings offer new insights into selectivity and flexibility in noncovalent interactions.