The formation of host–guest (H‐G) complexes between 1,8‐bis(diethylgallanyl)ethynylanthracene (H) and the N‐heterocycles pyridine and pyrimidine (G) was studied in solution using a combination of NMR titration and diffusion NMR experiments. For the latter, diffusion coefficients of potential host–guest structures in solution were compared with those of tailor‐made reference compounds of similar shape (synthesized and characterized by NMR, HRMS, and in part XRD). Highly dynamic behavior was observed in both cases, but with different host–guest species and equilibria. With increasing concentrations of the pyridine guest, the equilibrium H2⇄H2κ1‐G1⇄HG2 is observed (in the second step a host dimer coordinates one guest molecule); for pyrimidine the equilibrium H2→H1κ2‐G1⇄HG2 is observed (the formation of a 1:1 aggregate is the second step). Dynamic host–guest complexation was studied using a new combination of NMR titration and diffusion NMR experiments. The host is the bidentate 1,8‐bis(diethylgallanyl)ethynylanthracene, the guests are pyrimidine and pyridine. The analysis of the diffusion NMR experiments requires tailor‐made reference compounds of the same shape for comparison.