TRIARYLMETHANOL HOSTS AND ANALOGS .11. VERSATILITY IN COMPLEXATION OF6-MEMBERED HETEROCYCLIC GUESTS BY SINGLY BRIDGED TRIARYLMETHANOL HOSTS - X-RAY CRYSTAL-STRUCTURES AND THERMAL STABILITIES OF INCLUSION-COMPOUNDS WITH PIPERIDINE, THIOXANE DIOXANE, AND MORPHOLINE

9-Phenylfluoren-9-ol (1), 2,7-dibromo-9-phenylfluoren-9-ol (2), and 9- phenylethynylfluoren-9-ol (3) enclathrate different six-membered heter ocyclic guests involving piperidine, thioxane, dioxane, and morpholine . X-Ray crystal structure determinations of corresponding inclusion co mpounds [1 piperidine (1:1), 1 . thioxane . dioxane (2:2:1), a morphol ine (1:2), and 3 morpholine (1:1)] are reported, showing remarkable va riety in the packing relations. Host compound 1 forms H-bonded 1:1 hos t:guest units with both piperidine and thioxane, but in the latter cas e additional dioxane guests are incorporated in the crystal, thus yiel ding a ternary complex. Host compound 3 is capable of forming closed l oops of hydrogen bonds with full hydrogen bond saturation in its inclu sion compound with morpholine, whereas in the related morpholine compl ex of 2 H-bonded 1:2 associates are created without maximal saturation of the hydrogen bonds, and with different binding modes for the two g uests of the stoichiometric unit. In the crystals, the various H-bonde d host-guest units are linked together by Van der Waals' forces, occas ionally supported by weak electrostatic interactions. The stabilities of the four different inclusion compounds were studied by thermal anal ysis indicating complex decomposition modes.