Hemicarcerands 1-9, composed by coupling through four O(CH2)(4)O or four 1,3-(OCH2)(2)C6H4 bridging units in different pair combinations of three tetrol bowls (varying spanners, O(CH2)(n)O, n = 1, 2, or 3), have been examined for their abilities to incarcerate a variety of organic guest compounds of widely differing structures. When the conformationally flexible tetrol bowl (spanners = O(CH2)(3)O) was coupled lip-to-lip to either of two rigid bowl units (spanners OCH2O or O(CH2)(2)O), the rigid units tended to impose their shapes on the mobile units in the resulting hosts (H-1 NMR spectral and crystal structure evidence). Complexes were formed by heating to high temperatures host dissolved in a large excess of guest. High structural recognition in complexation was observed for the 1,3-(OCH2)(2)C6H4-bridged hosts to favor binding of 1,2-disubstituted as compared to 1,3- and 1,4-disubstituted benzenes as guests. Three new crystal structures of hemicarceplexes identical except for their spanner lengths are compared, and a fourth new structure allows comparison of identical hosts with different guests. Decomplexation rates are compared in some cases. Interesting new kinds of restricted rotations of guests with respect to hosts were observed. Three examples of trace impurities in guests being scavenged by the host were encountered.