The Influence of Hydrogen Bonding on Generation and Stabilization of Self-Assembled Layer Structure of 6-[4-(Trans-4-pentylcyclohexyl)phenoxy]hexane-1,2-diol

Abstract

The crystal structure of 6-[4-(trans-4-pentylcyclohexyl)phenoxy]hexane-1,2-diol (hereafter, CP2OH) has been determined by X-ray diffraction techniques. The CP2OH molecule crystallizes in the monoclinic crystal system with space group C2/c (#15). The asymmetric unit consists of one crystallographically independent molecule of CP2OH, and the unit cell contains eight molecules of CP2OH. The CP2OH molecules crystallize in sheets of layered arrangement along the [010] direction. The unit distance of 30 Å exists between neighbouring layers along the [010] direction. In each sheet of the layered structure of CP2OH, the molecules are aligned in an inclined manner in which the terminal hydroxyl groups lie in a head-to-head fashion generated by hydrogen bonding interactions.

The driving force behind the generation and stabilization of each sheet of the layered structure is attributed to the hydrogen bonded network between the terminal hydroxyl groups; O1 … O2 2.68(2) Å, and O1 … O1 2.64(5) Å in the self-assembled driven interactions amongst the CP2OH molecules. The intermolecular interactions are generally driven by hydrogen bonding and are also orientation dependent. Analysis of the molecular geometry suggest that neither the packing of the rigid phenoxy moiety nor the cyclohexyl moiety affects the molecular geometry in the hexane-1,2-diol moiety and pentyl chain, respectively. The length of CP2OH molecule measured from O1 to C23 is 21.98 Å. Intermolecular C … C contacts between neighboring alkyl chain molecules were not observed, and suggests that an influence of hydrophobic effects on the packing structure of the alkyl chain molecules are not strongly pronounced.

Keywords:

• crystal structure
• crystallography
• hydrogen bonding
• layered structures
• self assembly

ACKNOWLEDGMENT

The author E. M. wishes to express his sincere gratitude to the Japan Society for Promotion of Science (JSPS) for the fellowship awarded to pursue scientific research in Japan.