Novel, predicted patterns of supramolecular self-assembly, afforded by tetrameric R44(12) rings of C2 symmetry in the crystal structures of 2-hydroxy-1-cyclopentanecarboxylic acid, 2-hydroxy-1-cyclohexanecarboxylic acid and 2-hydroxy-1-cycloheptanecarboxylic acid.
Determination of the crystal structures of the homologous (1R*,2R*)-trans-2-hydroxy-1-cyclopentanecarboxylic acid (5T), (1R*,2S*)-cis-2-hydroxy-1-cyclohexanecarboxylic acid (6C) and (1R*,2S*)-cis-2-hydroxy-1-cycloheptanecarboxylic acid (7C) proved a predicted pattern of supramolecular close packing. The prediction was based on the common features observed in the crystal structures of six related 2-hydroxy-1-cyclopentanecarboxylic acids and analogous carboxamides [Kálmán et al. (2001). Acta Cryst. B57, 539-550]. This pattern is characterized by tetrameric R(4)(4)(12) rings of C(2) symmetry formed from dimeric R(2)(2)(12) rings. The C(2) symmetry of such tetramers is not common in the literature, usually they have C(i) symmetry. Both types of tetramers are formed from dimers with similar or opposite orientation. The R(2)(2)(12) dimers differ in their hydrogen bonds. In 5T the monomers are joined by a pair of O1[bond]H...O2[double bond]C bonds, whereas in 7C they are joined by a pair of O3[bond]H...O1-H bonds. In 6C 60% of the disordered R(2)(2)(12) dimers are similar to those in 7C, while 40% resemble those in 5T. Apart from these hydrogen-bonding differences and the ring-size differences, the three crystals exhibit isostructurality.
Kálmán
Alajos
A
Institute of Chemistry, Chemical Research Center, Hungarian Academy of Sciences, PO Box 17, Budapest 114, H-1525, Hungary. akalman@chemres.hu
Fábián
László
L
Argay
Gyula
G
Bernáth
Gábor
G
Gyarmati
Zsuzsanna
Z