The Plot Thickens: Gelation by Phenylalanine in Water and Dimethyl Sulfoxide

Abstract

Phenylalanine (Phe) is an amino acid of great interest as coupling of an aromatic group with a chiral hydrophilic region imparts a number of unique properties. Recently there has been an increased interest in the crystalline and gel forms of this compound, part as a result of the complex and undetermined structures of the resulting materials and the relationship of the solid forms of Phe with the disease phenylketonuria. In this report, we highlight the relationship between gelation, crystallization, and the dynamics of self-assembly processes of Phe. We do this by describing the gelation of the amino acid, the gel to crystal relationship, crystal structure predictions for this relatively simple compound, and the dynamics of assembly as determined by NMR in both water and dimethyl sulfoxide. This will provide guidance to future research into Phe assemblies, possible treatments for phenylketonuria, and diseases related to formation of amyloid-like fibers

Towards the Prediction of Global Solution State Properties for Hydrogen Bonded, Self‐Associating Amphiphiles

“…The self-associative binding modes of 1-31 weref irst explored within the solid state throught he use of single-crystal X-ray diffraction techniques. Crystal structures previously obtained for 8 and 16 show hydrogen bonded self-association through the formation of urea-anion tapes, [16] whilst 1,4,15,17,28,30,31 have been shown to dimerize through (thio)urea-anion hydrogen bond formation. [16,17] In contrast, ap revious structure obtained for 7 showed hydrogen bondeds elf-association throught he formation of urea-urea hydrogen bondedt apes.…”

“…Ac orrelation is alsoo bserved between CMC and compound counter cation (1,(8)(9)(10)(11). Here, theoreticalv alues of relative polarizability for those counter cations contained within the structures of 1, 8-11 werec alculated.…”

“…The formation of these bonds, combinedw ith hydrophilic/hydrophobic solvent interactions, stabilizea nd direct the formation of any resultant aggregate, whichi nt urn will dictate the global solution or solid state properties. [1] These non-covalent interactions include, but are not limited to, electrostatics, charge transfer,a nd hydrogen bond formation. [2] Gaining an understanding of the supramolecular interactions involved within the self-assembly process at the molecular level will allow informed construction of monomeric units, which will in turn enable the productiono fd esigner supramolecular functional materials, exhibiting globalp roperties of choice.…”

“…However,i nH 2 O9 5%/EtOH 5% larger self-associated aggregates > 100 nm in diameter were shown to exist. These structures were studied through ac ombination of dynamic light scattering (DLS), 1 HNMR, tensiometry (to derive CMC) and directly visualized throughmicroscopys tudies. These data showedacorrelationb etween increasing strength of dimerization and ad ecrease in CMC value, whichc ould be estimated through the use of low level computational modelling techniques, in a comparable but more accessible format than those predictive studies conducted by Nagarajan and Ruckenstein.…”

Amino Acid Based Self‐assembled Nanostructures: Complex Structures from Remarkably Simple Building Blocks

“…Recently, Lloyd and co-workers reported the gelation of unprotected Phe in DMSO. [58] They found that Phe could form gels at a much lower concentration in DMSO, as compared to water. Noticeably, the DMSO gels were transparent, unlike the opaque hydrogels.…”