Molecular and supramolecular structure of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane, tetrahydrofuran solvate

The crystal and molecular structure of 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spiro-bisindane tetrahydrofuran solvate, C21H24O4 . 2(C4H8O), has been determined by single crystal X-ray analysis: the space group is monoclinic, P2(1)/a, with a = 10.77(1), b = 25.357(8), c = 19.009(7) Angstrom, beta = 90.84(4)degrees, V = 5190(5) Angstrom(3), Z = 8, D-x = 1.24 gm/cm(3). The structure is a bis-catechol molecule which forms layers of either (R) or (S) configurational pairs. Layers are stacked to form solvent tunnels where adjoining layers are linked via hydrogen bonding. One hydroxyl oxygen on each end of catechol moieties act as a hydrogen donor while the remaining hydroxyl oxygen serves as donor and acceptor. The extensive hydrogen bonding, in conjunction with the spiro linkage forcing perpendicularly arranged aromatic rings, create the conditions for supramolecular control of the crystal structure. Consequently, they are also the primary factors responsible for the unusually high melting point of this bulky, branched, spiro bis-catechol compared to other alkyl derivatives of catechol molecules.