Molecular structure, supramolecular organization and thermotropic phase behavior of N-acylglycine alkyl esters with matched acyl and alkyl chains

作者：Reddy S Thirupathi; Swamy Musti J

来源：Chemistry and Physics of Lipids, 2017, 208: 43-51.

DOI：10.1016/j.chemphyslip.2017.09.002

• Phase transition
• Differential scanning calorimetry
• Single-crystal X-ray diffraction
• Powder X-ray diffraction
• Self-assembly
• C-H center dot center dot center dot O hydrogen bond

N-Acylglycines (NAGs), the endogenous single-tailed lipids present in rat brain and other mammalian tissues, play significant roles in cell physiology and exhibit interesting pharmacological properties. In the present study, a homologous series of N-acylglycine alkyl esters (NAGEs) with matched chains were synthesized and characterized. Results of differential scanning calorimetric studies revealed that all NAGEs exhibit a single sharp phase transition and that the transition enthalpy and entropy show a linear dependence on the N-acyl and ester alkyl chain length. The structure of N-myristoylglycine myristyl ester (NMGME), solved by single-crystal X-ray diffraction, showed that the molecule adopts a linear geometry and revealed that the structure of N-myristoyl glycyl moiety in NMGME is identical to that in N-myristoylglycine. The molecules are packed in layers with the polar functional groups of the ester and amide functionalities located at the center of the layer. The crystal packing is stabilized by N-H center dot center dot center dot O hydrogen bonds between the amide C=O and N-H groups of adjacent molecules as well as by C-H center dot center dot center dot O hydrogen bonds between the amide carbonyl and the methylene C-H adjacent to the ester carbonyl of neighboring molecules as well as between ester carbonyl and methylene group of the glycine moiety of adjacent molecules. Powder X-ray diffraction studies showed a linear dependence of the d-spacings on the acyl chain length, suggesting that all NAGEs adopt a structure similar to the packing exhibited in the crystal lattice of NMGME.

• 出版日期2017-11