Mechanism of crystalline self-assembly in aqueous medium: A combined cryo-TEM/kinetic study

Yaron Tidhar, Haim Weissman, Dmitry Tworowski, Boris Rybtchinski

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

Understanding the crystallization of organic molecules is a long-standing challenge. Herein, a mechanistic study on the self-assembly of crystalline arrays in aqueous solution is presented. The crystalline arrays are assembled from perylene diimide (PDI) amphiphiles bearing a chiral N-acetyltyrosine side group connected to the PDI aromatic core. A kinetic study of the crystallization process was performed using circular dichroism spectroscopy combined with time-resolved cryogenic transmission electron microscopy (cryo-TEM) imaging of key points along the reaction coordinate, and molecular dynamics simulation of the initial stages of the assembly. The study reveals a complex self-assembly process starting from the formation of amorphous aggregates that are transformed into crystalline material through a nucleation-growth process. Activation parameters indicate the key role of desolvation along the assembly pathway. The insights from the kinetic study correlate well with the structural data from cryo-TEM imaging. Overall, the study reveals four stages of crystalline self-assembly: 1)collapse into amorphous aggregates; 2)nucleation as partial ordering; 3)crystal growth; and 4)fusion of smaller crystalline aggregates into large crystals. These studies indicate that the assembly process proceeds according to a two-step crystallization model, whereby initially formed amorphous material is reorganized into an ordered system. This process follows Ostwald's rule of stages, evolving through a series of intermediate phases prior to forming the final structure, thus providing an insight into the crystalline self-assembly process in aqueous medium.

Original languageEnglish
Pages (from-to)10332-10342
Number of pages11
JournalChemistry - A European Journal
Volume20
Issue number33
DOIs
Publication statusPublished - Aug 11 2014

Keywords

  • amphiphiles
  • crystal growth
  • hydrophobic interactions
  • kinetics
  • self-assembly

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Organic Chemistry

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