Crystal structures of conformationally locked cyclitols: an analysis of hydrogen-bonded architectures and their implications in crystal engineering

Abstract

A qualitative study has been carried out on selected polycyclitols to evaluate the potential of conformational locking of hydroxy groups in lending predictability to the O-H···O hydrogen-bonding network observed in the crystal structures of such compounds. The polycyclitols employed in this study are conformationally locked with all the hydroxy groups destined to be axial owing to the trans ring fusion(s) in the polycyclic carbon framework. The consequent formation of intramolecular O-H···O hydrogen bonds between the 1,3-syn diaxial hydroxy groups now permits any packing pattern in the polycyclitols to be described in terms of a small group of intramolecularly bonded molecular motifs linked to their respective neighbors by four O-H···O bonds. By using this model and the results of CSD analyses of polyols as a guide, the O-H···O hydrogen-bonded packing motifs most likely to be observed in the crystal structure of each polycyclitol were proposed and compared with those obtained experimentally.