Targeting G-quadruplex (G4) DNA structures by small molecules is a potential strategy for directing gene therapy of cancer disease. Herein, novel insights into non-covalent interactions between a structurally diversified spectrum of ligands and a G-quadruplex DNA (formed in the c-Myc oncogene promoter region) are reported. Solvation-induced effects on and entropic contributions to the binding free energy are explored. In addition, the correlation of G4 domain motions and active site rearrangements with the binding of highest affinity ligands, being associated with the fundamentally distinguishable modes of interaction (external stacking: BRACO-19, TMPyP4, and CX-3543; groove binding: Sanguinarine, Tetrahydropalmatine, and Hoechst 33258), is quantitatively evaluated and elaborated by observing thermodynamic consequences of the receptor conformational flexibility changes in the asymptotic regime (t → ∞) of molecular dynamics (MD) simulation. BRACO-19 and Tetrahydropalmatine are identified as unique (thermodynamically favorable and highly selective) G4-DNA binders. Implications of the present study for experimental research are elucidated.