Inclusion properties and crystal structure of clathrates constructed basedon "pi-sandwich"

Inclusion behavior of structurally similar host compounds, l,4-bis[1-(9-ant hryl)-3-propen-1-on-3-yl]benzene (1) and 1,4-bis[3-(9-anthryl)-3-propen-1-o n-1-yl]benzene (2), has been studied. Both hosts preferred cyclic, non-bran ched small molecules as a guest component, to yield 2:2 clathrates specific ally. X-ray powder diffraction studies revealed that those 1:2 clathrates o f 1 and 2 were respectively isostructural. X-ray analyses of (1)(THF)(2) (P (1) over bar, a = 10.910(2), b = 19.656(5), c = 9.172(4) Angstrom, alpha = 95.58(3), beta = 93.67(2), gamma = 103.30(2)degrees, D-calc = 1.195 g cm(-3 ), Z = 2, and R = 0.067 for 8644 observed reflections) and (2)(1,4-dioxane) (2), (P2(1)/n, a = 5.661(1), b = 17.971(3), c = 18.619(3) Angstrom, beta = 91.37(2)degrees, D-calc = 1.254 g cm(-3), Z = 2, and R = 0.097 for 4353 obs erved reflections) illuminated that their guest preference should be ascrib ed to the commonly observed "pi -sandwich" structure, in which guest molecu les are enclathrated between two anthracene planes of the host molecules.