Phenylalanine (Phe)-derived molecules have been exploited as low molecular weight hydrogelators. Perturbing the hydrophobic and π–π interactions that promote self-assembly and hydrogelation of these derivatives will facilitate improved understanding of hydrogelation phenomena and the design of small molecule hydrogelators with novel properties. The efficient self-assembly and hydrogelation of Fmoc-protected pentafluorophenylalanine (Fmoc-F₅-Phe) are reported herein. Suspensions of Fmoc-F₅-Phe in water undergo rapid self-assembly to entangled fibrillar structures within minutes, giving rise to rigid supramolecular gels. Self-assembly occurs at concentrations as low as 2 mM (0.1 wt%). Variation of the fluorinated aromatic side chain or N-terminal functionalization perturbs hydrogelation, implicating fluorous and π–π interactions as the primary determinants for molecular recognition and self-assembly. The hydrophobic and electronic properties of F₅-Phe provide remarkable potential for functional self-assembly in a minimal amino acid scaffold.

Ordering at short-length scales is a universal feature of the glassy state. Experiments on boron oxide and other materials indicate that ordering on mesoscopic-length scales may also be universal. The high-resolution nuclear magnetic resonance (NMR) measurements of oxygen in boron oxide glass presented here provide evidence for structural units responsible for ordering on short- and intermediate-length scales. At the molecular level, planar BO _3/2 units accounted for the local ordering. Oxygen-17 NMR spectra resolved detailed features of the inclusion of these units in boroxol rings, oxygen bridging two rings, and oxygen shared between two nonring BO _3/2 units. On the basis of these and corroborative boron-11 NMR and scattering results, boron oxide glass consists of domains that are rich or poor in boroxol rings; these domains are proposed to be the structural basis of intermediate-range order in glassy boron oxide.