Comparing the host behaviour of N,N'-bis(9-phenyl-9-thioxanthenyl)ethylenediamine and N,N'-bis(9-phenyl-9-xanthenyl)ethylenediamine in the presence of various alkylated aromatic and aniline guests: crystal engineering considerations

In this work, we investigate and compare the host behaviour of two structurally related compounds, N,N′-bis(9-phenyl-9-thioxanthenyl)ethylenediamine (H1) and N,N′-bis(9-phenyl-9-xanthenyl)ethylenediamine (H2), in the presence of two guest solvent series, namely alkylated aromatics (toluene, ethylbenzene and cumene) and anilines (aniline, N-methylaniline and N,N-dimethylaniline). Contrasting host behaviours were observed when each of H1 and H2 was recrystallized from these individual guest solvents, with H1 including the smaller guests only (toluene, ethylbenzene, aniline and N-methylaniline), and H2 the larger guests (cumene, N-methylaniline and N,N-dimethylaniline). The only common guest to be enclathrated by both hosts was N-methylaniline. When presented with competing equimolar and non-equimolar guests from each series, the contrasting host behaviour persisted, and H1 and H2 always preferred the smaller and larger guests in the mixture, respectively. Single crystal X-ray diffraction and thermal analyses were employed in order to elucidate the reasons for these observations.