Extent of Intramolecular π‐Stacks in Aqueous Solution in Mixed‐Ligand Copper(II) Complexes Formed by Heteroaromatic Amines and Several 2‐Aminopurine Derivatives of the Antivirally Active Nucleotide Analog 9‐[2‐(Phosphonomethoxy)ethyl]adenine (PMEA) | Publicación