The effect of cation–π inter­actions on the stability and electronic properties of anti­cancer drug Altretamine: a theoretical study

The present work utilizes density functional theory (DFT) calculations to study the influence of cation–π inter­actions on the electronic properties of the complexes formed by Altretamine [2,4,6-tris­(di­methyl­amino)-1,3,5-triazine], an anti­cancer drug, with mono- and divalent (Li⁺, Na⁺, K⁺, Be²⁺, Mg²⁺ and Ca²⁺) metal cations. The structures were optimized with the M06-2X method and the 6-311++G(d,p) basis set in the gas phase and in solution. The theory of `Atoms in Mol­ecules' (AIM) was applied to study the nature of the inter­actions by calculating the electron density ρ(r) and its Laplacian at the bond critical points. The charge-transfer process during complexation was evaluated using natural bond orbital (NBO) analysis. The results of DFT calculations demonstrate that the strongest/weakest inter­actions belong to Be²⁺/K⁺ complexes. There are good correlations between the achieved densities and the amounts of charge transfer with the inter­action energies. Finally, the stability and reactivity of the cation–π inter­actions can be determined by quantum chemical computation based on the mol­ecular orbital (MO) theory.