Journal Article

PUBDB-2022-06521

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png The Complete Phase Diagram of Monolayers of Enantiomeric N-Stearoyl-threonine Mixtures with Preferred Heterochiral Interactions

Mukhina, T.Extern* ; Richter, L. ; Vollhardt, D. (Corresponding author)MPG* ; Brezesinski, G.Extern* ; Schneck, E. (Corresponding author)Extern*

2022
ACS Publ. Washington, DC

This record in other databases:        

Please use a persistent id in citations: doi:10.1021/acs.langmuir.2c01936  doi:10.3204/PUBDB-2022-06521

Abstract: Langmuir monolayers of chiral amphiphiles are well-controlled model systems for the investigation of phenomena related to stereochemistry. Here, we have investigated mixed monolayers of one pair of enantiomers (L and D) of the amino-acidbased amphiphile N-stearoyl-threonine. The monolayer characteristics were studied by pressure−area isotherm measurements and grazing incidence X-ray diffraction (GIXD) over a wide range of mixing ratios defined by the D-enantiomer mole fraction $x_D$. While the isotherms provide insights into thermodynamical aspects, such as transition pressure, compression/decompression hysteresis, and preferential homo- and heterochiral interactions, GIXD reveals the molecular structural arrangements on the Ångström scale. Dominant heterochiral interactions in the racemic mixture lead to compound formation and the appearance of a nonchiral rectangular lattice, although the pure enantiomers form a chiral oblique lattice. Miscibility was found to be limited to mixtures with 0.27 ≲ $x_D$ ≲ 0.73, as well as to both outer edges ($x_D$ ≲ 0.08 and $x_D$ ≳ 0.92). Beyond this range, coexistence of oblique and rectangular lattices occurs, as is clearly seen in the GIXD patterns. Based on the results, a complete phase diagram with two eutectic points at $x_D$ ≈ 0.25 and $x_D$ ≈ 0.75 is proposed. Moreover, N-stearoyl-threonine was found to have a strong tendency to form a hydrogen-bonding network between the headgroups, which promotes superlattice formation.

---

Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)

Research Program(s):

1. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)

Experiment(s):

1. PETRA Beamline P08 (PETRA III)
2. DORIS Beamline BW1 (DORIS III)

Appears in the scientific report 2022

---

Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

---