Modification of tube size and shape in a helical tubuland inclusion lattice formed by a new family of diol hosts: syntheses and crystal structures

Abstract

The four diols exo-2,exo-6-dihydroxy-2,6-dimethylbicyclo[3.3.1]nonane (1), syn-2,syn-7-dihydroxy-2,7-dimethyltricyclo[4.3.1.1^3,8]undecane (2), anti-2,anti-7-dihydroxy-2,7-dimethyl-tricyclo[4.3.1.1^3,8]undecane (3), and syn-2,syn-8-dihydroxy-2,8-dimethyltricyclo[5.3.1.1^3,9]dodecane (4) have been synthesised by stereospecific reaction of mercury(II) acetate or methyl-lithium with the diolefin or diketone precursor. All four compounds adopt the same crystal structure type, in which diol molecules connect a hexagonal array of hydrogen-bonded spines, in space group P3₁21, creating helical tubular cavities in the host crystal. However, different bridges between the two hydroxy functions of the host molecules cause substantial differences in the dimensions of the crystal lattice and in the shapes and unobstructed cross-sectional areas A^un of the tubes. For (1)–(4) respectively, unit-cell volumes are 897, 1 042, 858, and 1 150 ų, and A^un values are 22.4, 30.2, 4.7, and 34.7 Ų.