To gain further insights into and elucidate the structures of the tetralactam series, attempts were made to grow diffractionquality single crystals of each compound using various techniques and system conditions. Due to the low yield of some compounds, receptor solutions made for NMR studies were collected and reused to grow crystals. Therefore, the majority of the successfully grown single crystals (3c, 2a•Cl -, 2c•Cl -, 3a•Cl -, 4b•Cl -, 2a•F -, and 3a•F -) were obtained from the slow diffusion of H2O vapour into DMSO-d6/H2O (0.5%) solutions (1 mM), which contained a large excess of either TBACl or TBAF (Figure , a-c). The solid-state structures tabulated crystallographic information and CCDC deposition numbers for each of the obtained crystal structures can be found in the ESI (Figure -S63 and Table -S69). Tetralactam 1b•2Cl -was dissolved in hot CH2Cl2 with an excess of TBACl. Once completely dissolved, the solution was allowed to cool to room temperature, and the mother liquor was separated from the resultant precipitate before being allowed to stand while single crystals grew.