Simple Tyrosine Derivatives Act as Low Molecular Weight Organogelators

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.

Triggering a transient organo-gelation system in a chemically active solvent

“…situ, 15 and enzyme-mediated chemical changes can trigger selfassembly. [16][17][18] Catalysis plays an intimate role in controlling nonequilibrium fuelled systems in both assembly/disassembly pathways.…”

Ultrashort Peptide Self-Assembly: Front-Runners to Transport Drug and Gene Cargos

“…The analysis outcomes made this molecule more special as the gelation could be carried out in all classes of solvents; be it polar, protic, apolar, etc. The gelation in sunflower oil and diesel makes it an appropriate candidate for drug delivery (Aykent et al, 2019). Further investigations revealed the same capability of other enantiomer, H-D-Tyr(tBu)-OH to form the organogel while racemic H-DL-Tyr(tBu)-OH was unsuccessful to do so.…”

“…Further investigations revealed the same capability of other enantiomer, H-D-Tyr(tBu)-OH to form the organogel while racemic H-DL-Tyr(tBu)-OH was unsuccessful to do so. The new work also exposed the role of tert-butyl moiety as H-Tyr-OH, H-Phe-OH and H-Tyr(Me)-OH could not form gel while H-Tyr(tBu)-OH could do so as mentioned above (Aykent et al, 2019).…”

Amine-Derivatized l-Phenylalanine and l-Tyrosine as Versatile Self-Assembled Platforms of Diverse Supramolecular Architectures: From Mesocrystals to Organogels

“…Apparently, based on the number of known examples, one of the most frequent N-derivatization is the amide generation, but no other, such as the obtaining of a secondary amine group. So far, Tyr does not give rise to hydrogels like Phe, and on the other hand, there are just a few examples of supramolecular gels constructed by Tyr-based building blocks . Inspired by the remarkable self-assembly properties of these two amino acids and having in mind the possibility to modify and expand their supramolecular and physical properties through derivatization, we synthesized new molecules using the aldehyde piperonal, named as Phepip and Tyrpip (Figure ).…”

“…So far, Tyr does not give rise to hydrogels like Phe, and on the other hand, there are just a few examples of supramolecular gels constructed by Tyrbased building blocks. 42 Inspired by the remarkable selfassembly properties of these two amino acids and having in mind the possibility to modify and expand their supramolecular and physical properties through derivatization, we synthesized new molecules using the aldehyde piperonal, named as Phepip and Tyrpip (Figure 1). We recently tested their use as ligands for the construction of Ni(II) coordination complexes, and it was demonstrated that the nuclearity and properties of the resulting systems were related to the selfassembly, where the presence or absence of the phenolic OH was critical.…”