Simple Tyrosine Derivatives Act as Low Molecular Weight Organogelators

Sci Rep. 2019 Mar 20;9(1):4893. doi: 10.1038/s41598-019-41142-z.

Abstract

The gelation of L-Tyr(tBu)-OH in tetrahydrofuran (THF) was discovered serendipitously. It was noted that this tremendously low molecular weight (LMW) compound has the ability to gel a wide variety of organic solvents (e.g., N,N-Dimetylformamide (DMF), THF, butanol, toluene), even in very low concentrations (i.e., 0.1 wt/v% in DMF). Addition of bases such as NaOH and piperidine enhanced the gel property. By changing the side-chain protecting group to tert-butyldimethylsilyl (TBDMS), a fluoride ion-responsive organogel was also acquired. This new organogelator responded fluoride ion concentration as low as 0.2 ppm. Characterization of microstructures and gel behaviours were studied by powder X-Ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), rheological measurements and molecular dynamics (MD) simulations. Experimental observations and theoretical simulations consistently show a fibre-like structure of the gel, in which the organogelator molecules are held together via a dense network of hydrogen bonds, and via van der Waals interactions between hydrophobic groups.

MeSH terms

  • Furans / chemistry*
  • Gels / chemistry*
  • Hydrogen Bonding
  • Hydrophobic and Hydrophilic Interactions
  • Microscopy, Electron, Transmission
  • Molecular Dynamics Simulation
  • Molecular Weight
  • Solvents / chemistry
  • Tyrosine / chemistry*
  • X-Ray Diffraction

Substances

  • Furans
  • Gels
  • Solvents
  • tetrahydrofuran
  • Tyrosine