Fig. 1. Considered interaction types and geometric parameters used during data collection. Distances da, dc, and dp are between the centroid of the aromatic ring and the anion, cation, and centroid of another aromatic ring, respectively. Angles αa, αc, and αp, are formed by the vector connecting the ring centroid with the anion, cation, and another ring plane, respectively. Angle αpp, is formed between ring planes. A comprehensive definition of centers and centroids for each amino acid, nucleic base, and ion is offered as ESI Table 1.† .
